Determining bioclimatic space of Himalayan alder for agroforestry systems in Nepal

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Santosh Kumar Rana

2018-02-01

Full Text Available Himalayan alder species are proven to be very useful in traditional as well as contemporary agroforestry practice. These nitrogen-fixing trees are also useful in the land restoration. Therefore, understanding the distribution of Himalayan alder and the potential zone for plantation is meaningful in the agroforestry sector. Suitable climatic zones of Alnus spp. were modelled in MaxEnt software using a subset of least correlated bioclimatic variables for current conditions (1950–2000, topographic variables (DEM derived and Landuse Landcover (LULC data. We generated several models and selected the best model against random models using ANOVA and t-test. The environmental variables that best explained the current distribution of the species were identified and used to project into the future. For future projections, ensemble scenarios of climate change projection derived from the results of 19 Earth System Models (ESM were used. Our model revealed that the most favorable conditions for Alnus nepalensis are in central Nepal in the moist north-west facing slope, whereas for Alnus nitida they are in western Nepal. The major climatic factor that contributes to Alnus species distribution in Nepal appears to be precipitation during the warmest quarter for A. nepalensis and precipitation during the driest quarter for A. nitida. Future projections revealed changes in the probability distribution of these species, as well as where they need conservation and where they can be planted. Also, our model predicts that the distribution of Alnus spp. in hilly regions will remain unchanged, and therefore may represent sites that can be used to revitalize traditional agroforestry systems and extract source material for land restoration.

Short communication: A laboratory study to validate the impact of the addition of Alnus nepalensis leaf litter on carbon and nutrients mineralization in soil

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GAURAV MISHRA

2016-04-01

Full Text Available Abstract. Mishra G, Giri K, Dutta A, Hazarika S and Borgohain P. 2015. A laboratory study to validate the impact of the addition of Alnus nepalensis leaf litter on carbon and nutrients mineralization in soil. Nusantara Bioscience 8: 5-7. Plant litter or residues can be used as soil amendment to maintain the carbon stock and soil fertility. The amount and rate of mineralization depends on biochemical composition of plant litter. Alnus nepalensis (Alder is known for its symbiotic nitrogen fixation and capability to restore fertility of degraded lands. A laboratory incubation experiment was conducted for 60 days under controlled conditions to validate the carbon and nutrients mineralization potential of alder litter. Soil fertility indicators, i.e. soil organic carbon (SOC, available nitrogen (N, available phosphorus (P, and available potassium (K were analyzed using standard procedures. Significant differences were observed in the soil properties after addition of litter. Nutrient composition of alder litter was found superior by providing significantly higher organic matter and helped in better nutrient cycling. Therefore, alder based land use system may be replicated in other degraded lands or areas for productivity enhancement which is important for sustaining biodiversity and soil fertility.

Physical properties and fiber dimension in Stem, Branch and root of Alder Wood

OpenAIRE

Moya-Roque, Roger; Kiaei, Majid

2015-01-01

The aim of this study was to determine physical properties and fiber dimensions in stem, branch and root wood for alder (Alnus glutinosa L) species. For this purpose, three normal alder trees were selected from Khanican forest in north of Iran. Disks were taken from three parts such as stem, branch and root of trees. Testing samples were randomly taken at disk surfaces to examine the physical properties (according to the ISO standard for oven-dry density and volumetric shrinkage) and fiber di...

Comparative effects of urea fertilizer and red alder in a site III, coast Douglas-fir plantation in the Washington Cascade Range.

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Richard E. Miller; Harry W. Anderson; Marshall Murray; Rick. Leon

2005-01-01

Five randomly assigned treatments were used to quantify effects of adding varying numbers of red alder (Alnus rubra Bong.) or nitrogen (N) fertilization on growth of a 10-year-old conifer plantation at a medium quality site in the western Washington Cascade Range. Zero, 20, 40, and 80 alder trees per acre were retained along with about 300 conifers...

Developing Biomass Equations for Western Hemlock and Red Alder Trees in Western Oregon Forests

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Krishna Poudel; Hailemariam Temesgen

2016-01-01

Biomass estimates are required for reporting carbon, assessing feedstock availability, and assessing forest fire threat. We developed diameter- and height-based biomass equations for Western hemlock (Tsuga heterophylla (Raf.) Sarg.) and red alder (Alnus rubra Bong.) trees in Western Oregon. A system of component biomass...

Alder and the Golden Fleece: high diversity of Frankia and ectomycorrhizal fungi revealed from Alnus glutinosa subsp. barbata roots close to a Tertiary and glacial refugium

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Melanie Roy

2017-07-01

Full Text Available Background Recent climatic history has strongly impacted plant populations, but little is known about its effect on microbes. Alders, which host few and specific symbionts, have high genetic diversity in glacial refugia. Here, we tested the prediction that communities of root symbionts survived in refugia with their host populations. We expected to detect endemic symbionts and a higher species richness in refugia as compared to recolonized areas. Methods We sampled ectomycorrhizal (EM root tips and the nitrogen-fixing actinomycete Frankia communities in eight sites colonized by Alnus glutinosa subsp. barbata close to the Caucasus in Georgia. Three sites were located in the Colchis, one major Eurasian climatic refugia for Arcto-Tertiary flora and alders, and five sites were located in the recolonized zone. Endemic symbionts and plant ITS variants were detected by comparing sequences to published data from Europe and another Tertiary refugium, the Hyrcanian forest. Species richness and community structure were compared between sites from refugia and recolonized areas for each symbionts. Results For both symbionts, most MOTUs present in Georgia had been found previously elsewhere in Europe. Three endemic Frankia strains were detected in the Colchis vs two in the recolonized zone, and the five endemic EM fungi were detected only in the recolonized zone. Frankia species richness was higher in the Colchis while the contrary was observed for EM fungi. Moreover, the genetic diversity of one alder specialist Alnicola xanthophylla was particularly high in the recolonized zone. The EM communities occurring in the Colchis and the Hyrcanian forests shared closely related endemic species. Discussion The Colchis did not have the highest alpha diversity and more endemic species, suggesting that our hypothesis based on alder biogeography may not apply to alder’s symbionts. Our study in the Caucasus brings new clues to understand symbioses biogeography and

Alnus acuminata in dual symbiosis with Frankia and two different ectomycorrhizal fungi (Alpova austroalnicola and Alpova diplophloeus) growing in soilless growth medium

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Alejandra G. Becerra; Euginia Menoyo; Irene Lett; Ching Y. Li

2009-01-01

In this study we investigated the capacity of Andean alder (Alnus acuminata Kunth), inoculated with Frankia and two ectomycorrhizal fungi (Alpova austroalnicola Dominguez and Alpova diplophloeus [Zeller and Dodge] Trappe and Smith), for nodulation and growth in pots of a soilless medium...

Short communication: A laboratory study to validate the impact of the addition of Alnus nepalensis leaf litter on carbon and nutrients mineralization in soil

OpenAIRE

GAURAV MISHRA; KRISHNA GIRI; ANTARA DUTTA

2016-01-01

Abstract. Mishra G, Giri K, Dutta A, Hazarika S and Borgohain P. 2015. A laboratory study to validate the impact of the addition of Alnus nepalensis leaf litter on carbon and nutrients mineralization in soil. Nusantara Bioscience 8: 5-7. Plant litter or residues can be used as soil amendment to maintain the carbon stock and soil fertility. The amount and rate of mineralization depends on biochemical composition of plant litter. Alnus nepalensis (Alder) is known for its symbiotic nitrogen fixa...

Determination of isotopic identity of nitrogen fixed by Frankia associated with the genus Alnus

International Nuclear Information System (INIS)

Kurdali, F.; Domenach, A.M.; Daniere, C.; Bardin, R.

1988-01-01

To use the 15 N natural abundance method to evaluate the symbiotic nitrogen fixation by actinorhizal trees, it is necessary to determine the isotopic identity of assimilated nitrogen from two sources: the soil and the air. This study reports an isotopic value of fixed nitrogen by two alder species (Alnus Incana(L.) Moench and Alnus glutinosa(L.) Gaertn.) growing on nitrogen-free medium in greenhouse experiments. The δ 15 N value of the aerial parts was -2. This value was stable with time and did not depend on the Frankia strains used. This value could be used to estimate the nitrogen fixation in the natural ecosystem. Other parameters such as the mobilization of nitrogen reserves and the choice of the reference plant must be investigated to apply this method. The nodules of these two alder species were enriched in 15 N relative to the rest of the plant but there was no relationship between symbiotic effectiveness of Frankia strains and 15 N enrichment of nodules. On the other hand, for naturally growing trees, an enrichment in 15 N was found primarily in the vesicles of nodules that are the sites of nitrogen fixation. 37 refs., 4 figs., 3 tabs. (author)

Consumer preferences for kitchen cabinets made from red alder: a comparison to other hardwoods.

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David L. Nicholls; Geoffrey H. Donovan; Joseph. Roos

2004-01-01

In Alaska, red alder (Alnus rubra Bong.) is an abundant but commercially underutilized species despite having properties suitable for higher value products, including furniture and cabinetry. However, it laces the name recognition of mote traditional hardwoods. Our research measured the effect of this lack of familiarity on consumer preferences...

Variation in damage from growing-season frosts among open-pollinated families of red alder.

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Kevin C. Peeler; Dean S. DeBell

1987-01-01

Repeated growing-season frosts during late April and early May 1985 caused extensive damage to red alder (Alnus rubra Bong.) seedlings in a newly planted research trial in western Washington. About two-thirds of the seedlings were severely damaged (entire stem damaged or necrotic). Such damage varied by family, from 50 percent of seedlings in the...

Size of Douglas-fir trees in relation to distance from a mixed red alder - Douglas-fir stand

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R.E. Miller; D.L. Reukema; T.A. Max

1993-01-01

Variation in diameter, height, and stem volume of 57-year-old Douglas-fir(Pseudotsuga menziesii var. menziesii (Mirb.) Franco) was related to distance of these trees from a 27 m wide strip in the same Douglas-fir plantation that had been interplanted with red alder (Alnus rubra Bong.). Within the...

How Does Salinity Shape Bacterial and Fungal Microbiomes of Alnus glutinosa Roots?

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Thiem, Dominika; Gołębiewski, Marcin; Hulisz, Piotr; Piernik, Agnieszka; Hrynkiewicz, Katarzyna

2018-01-01

Black alder (Alnus glutinosa Gaertn.) belongs to dual mycorrhizal trees, forming ectomycorrhizal (EM) and arbuscular (AM) root structures, as well as represents actinorrhizal plants that associate with nitrogen-fixing actinomycete Frankia sp. We hypothesized that the unique ternary structure of symbionts can influence community structure of other plant-associated microorganisms (bacterial and fungal endophytes), particularly under seasonally changing salinity in A. glutinosa roots. In our study we analyzed black alder root bacterial and fungal microbiome present at two forest test sites (saline and non-saline) in two different seasons (spring and fall). The dominant type of root microsymbionts of alder were ectomycorrhizal fungi, whose distribution depended on site (salinity): Tomentella, Lactarius, and Phialocephala were more abundant at the saline site. Mortierella and Naucoria (representatives of saprotrophs or endophytes) displayed the opposite tendency. Arbuscular mycorrhizal fungi belonged to Glomeromycota (orders Paraglomales and Glomales), however, they represented less than 1% of all identified fungi. Bacterial community structure depended on test site but not on season. Sequences affiliated with Rhodanobacter, Granulicella, and Sphingomonas dominated at the saline site, while Bradyrhizobium and Rhizobium were more abundant at the non-saline site. Moreover, genus Frankia was observed only at the saline site. In conclusion, bacterial and fungal community structure of alder root microsymbionts and endophytes depends on five soil chemical parameters: salinity, phosphorus, pH, saturation percentage (SP) as well as total organic carbon (TOC), and seasonality does not appear to be an important factor shaping microbial communities. Ectomycorrhizal fungi are the most abundant symbionts of mature alders growing in saline soils. However, specific distribution of nitrogen-fixing Frankia (forming root nodules) and association of arbuscular fungi at early stages of

The patterns of Corylus and Alnus pollen seasons and pollination periods in two Polish cities located in different climatic regions.

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Puc, Małgorzata; Kasprzyk, Idalia

2013-01-01

This study compares phenological observations of Corylus (hazel) and Alnus (alder) flowering with airborne pollen counts of these taxa recorded using volumetric spore traps (2009-2011). The work was carried out in the Polish cities of Szczecin and Rzeszów that are located in different climatic regions. Correlations between pollen concentrations and meteorological data were investigated using Spearman's rank correlation analysis. The timings of hazel and alder pollination and the occurrence of airborne pollen varied greatly and were significantly influenced by meteorological conditions ( p  sunlight (insolated) and sheltered from the wind. On the other hand, a delay in the timing of pollination was observed in quite sunny but very windy sites. In Rzeszów, maximum hazel pollen concentrations did not coincide with the period of full pollination (defined as between 25 % hazel and alder and 75 % of flowers open). Conversely, in Szczecin, the highest hazel pollen concentrations were recorded during phenophases of the full pollination period. The period when the highest alder pollen concentrations were recorded varied between sites, with Rzeszów recording the highest concentrations at the beginning of pollination and Szczecin recording alder pollen throughout the full pollination period. Substantial amounts of hazel and alder pollen grains were recorded in the air of Rzeszów (but not Szczecin) before the onset of the respective pollen seasons.

The Phytophthora species assemblage and diversity in riparian alder ecosystems of western Oregon, USA.

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Sims, Laura Lee; Sutton, Wendy; Reeser, Paul; Hansen, Everett M

2015-01-01

Phytophthora species were systematically sampled, isolated, identified and compared for presence in streams, soil and roots of alder (Alnus species) dominated riparian ecosystems in western Oregon. We describe the species assemblage and evaluate Phytophthora diversity associated with alder. We recovered 1250 isolates of 20 Phytophthora species. Only three species were recovered from all substrates (streams, soil, alder roots): P. gonapodyides, the informally described "P. taxon Pgchlamydo", and P. siskiyouensis. P. alni ssp. uniformis along with five other species not previously recovered in Oregon forests are included in the assemblage: P.citricola s.l., P. gregata, P. gallica, P. nicotianae and P. parsiana. Phytophthora species diversity was greatest in downstream riparian locations. There was no significant difference in species diversity comparing soil and unwashed roots (the rhizosphere) to stream water. There was a difference between the predominating species from the rhizosphere compared to stream water. The most numerous species was the informally described "P. taxon Oaksoil", which was mainly recovered from, and most predominant in, stream water. The most common species from riparian forest soils and alder root systems was P. gonapodyides. © 2015 by The Mycological Society of America.

Antifungal constituents in alnus acuminata H.B.K. nodules Constituyentes antifungicos en nódulos radicales de Alnus Acuminata H.B.K.

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Gonzalez Jaime

1988-12-01

Full Text Available Alnus acuminata. H.B.K. is a native specimen of economic importance. that is characterized for having root nodules
that can fix nitrogen. The nodules chemical composition has not been sstablished, but, it has been seen that it has influence over the soil microflora. In order to establish the chemical composition and the activity of the obtained fractions, there were made extractions of the alder nodules. The insulated compounds were; xylose and ribose; an aromatic carboxylicaeid, an fatty aeid, an phenolic biarylheptanoid and a flavonoid glycosic. were also founded. The Fusarium oxysporum and Pythium sp. growing was inhibited by this last one sustance.Alnus acuminata. H.B.K. es una especie nativa de importancia económica que se caracteriza por tener nódulos radicales
fijadores de nitrógeno. La composición química de los nódulos no se ha establecido; sin embargo, se ha observado que actúa sobre la microflora del suelo. Con el fin de establecer la composición química de las fracciones obtenidas, se.realizaron extracciones a partir de nódulos de Aliso. Los compuestos
aislados 'fueron: xilosa y ribosa; además se caracterizaron un ácido carboxílico aromático, un ácido graso, un biariheptanoide
fenólico y un glicósido de flavonoide. Esta última sustancia inhibió el crecimiento de Fusarium oxvsporum y Pythium sp.

Comparison of 226Ra nuclide from soil by three woody species Betula pendula, Sambucus nigra and Alnus glutinosa during the vegetation period

International Nuclear Information System (INIS)

Soudek, Petr; Petrova, Sarka; Benesova, Dagmar; Tykva, Richard; Vankova, Radomira; Vanek, Tomas

2007-01-01

The uptake of 226 Ra from the contaminated soil was compared in three woody species: alder (Alnus glutinosa), birch (Betula pendula) and elder (Sambucus nigra). The 226 Ra activities increased during the vegetation periods (in 2003, 2004 and 2005) both in the leaves and flowers + seeds. The highest accumulation was found in birch, reaching 0.41 Bq/g DW in the leaves (at the end of the vegetation period in 2003). The lowest 226 Ra accumulation was determined in alder. The extent of 226 Ra accumulation in the leaves of woody species demonstrates that these pioneer woody species can be used as remediation alternative to the use of herbs, provided that the removal of fallen leaves could be achieved in the end of vegetation period

Technological and Thermal Properties of Thermoplastic Composites Filled with Heat-treated Alder Wood

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Mürşit Tufan

2016-02-01

Full Text Available This study investigated the effect of heat-treated wood content on the water absorption, mechanical, and thermal properties of wood plastic composites (WPCs. The WPCs were produced from various loadings (30, 40, and 50 wt% of heat-treated and untreated alder wood flours (Alnus glutinosa L. using high-density polyethylene (HDPE with 3 wt% maleated polyethylene (MAPE coupling agent. All WPC formulations were compression molded into a hot press for 3 min at 170 ºC. The WPCs were evaluated using mechanical testing, Fourier transform infrared spectroscopy (FTIR, thermogravimetric analysis (TGA, and differential scanning calorimetry (DSC. The mechanical property values of the WPC specimens decreased with increasing amounts of the heat-treated wood flour, except for the tensile modulus values. The heat treatment of alder wood slightly increased the thermal stability of the WPCs compared with the reference WPCs. The crystallization degree (Xc and the enthalpy of crystallization of the WPCs slightly decreased with increasing content of the heat-treated wood flour. However, all WPCs containing the heat-treated alder wood flour showed a higher crystallinity degree than that of the virgin HDPE.

Factors affecting distribution of wood, detritus, and sediment in headwater streams draining managed young-growth red alder - Conifer forests in southeast Alaska

Science.gov (United States)

Gomi, T.; Johnson, A.C.; Deal, R.L.; Hennon, P.E.; Orlikowska, E.H.; Wipfli, M.S.

2006-01-01

Factors (riparian stand condition, management regimes, and channel properties) affecting distributions of wood, detritus (leaves and branches), and sediment were examined in headwater streams draining young-growth red alder (Alnus rubra Bong.) - conifer riparian forests (40 years old) remained in channels and provided sites for sediment and organic matter storage. Despite various alder-conifer mixtures and past harvesting effects, the abundance of large wood, fine wood, and detritus accumulations significantly decreased with increasing channel bank-full width (0.5-3.5 m) along relatively short channel distances (up to 700 m). Changes in wood, detritus, and sediment accumulations together with changes in riparian stand characteristics create spatial and temporal variability of in-channel conditions in headwater systems. A component of alder within young-growth riparian forests may benefit both wood production and biological recovery in disturbed headwater stream channels. ?? 2006 NRC.

Ecotoxicological effects evoked in hydrophytes by leachates of invasive Acer negundo and autochthonous Alnus glutinosa fallen off leaves during their microbial decomposition

International Nuclear Information System (INIS)

Krevš, Alina; Darginavičienė, Jūratė; Gylytė, Brigita; Grigutytė, Reda; Jurkonienė, Sigita; Karitonas, Rolandas; Kučinskienė, Alė; Pakalnis, Romas; Sadauskas, Kazys; Vitkus, Rimantas

2013-01-01

Throughout 90-day biodegradation under microaerobic conditions, invasive to Lithuania species boxelder maple (Acer negundo) leaves lost 1.5-fold more biomass than that of autochthonous black alder (Alnus glutinosa), releasing higher contents of N tot , ammonium and generating higher BOD 7 . Boxelder maple leaf leachates were characterized by higher total bacterial numbers and colony numbers of heterotrophic and cellulose-decomposing bacteria than those of black alder. The higher toxicity of A. negundo aqueous extracts and leachates to charophyte cell (Nitellopsis obtusa), the inhabitant of clean lakes, were manifested at mortality and membrane depolarization levels, while the effect on H + -ATPase activity in membrane preparations from the same algae was stronger in case of A. glutinosa. Duckweed (Lemna minor), a bioindicator of eutrophic waters, was more sensitive to leaf leachates of A. glutinosa. Fallen leaves and leaf litter leachates from invasive and native species of trees, which enter water body, affect differently microbial biodestruction and aquatic vegetation in freshwater systems. - Highlights: ► We examined Acer negundo and Alnus glutinosa leaf extract effects on hydrophytes. ► Nitellopsis obtusa and Lemna minor responded differently to leaf litter leachates. ► 90-day biodegraded A. negundo leaves lost twofold more biomass than that of A. glutinosa. ► A. negundo leachates evoked higher mortality and cell depolarization of N. obtusa. ► Leachates affected H + -ATPase activity in algae membrane preparations. - Fallen leaves and leaf litter leachates from invasive and native species of trees, which enter waterbody can be environmental factor affecting differently microbial biodestruction and aquatic vegetation in freshwater systems, thus influencing ecological scenarios.

Early wide spacing in red alder (Alnus rubra Bong.): effects on stem form and stem growth.

Science.gov (United States)

Bernard T. Bormann

1985-01-01

A thinning trial was established in 1962 in a 7-year-old red alder stand in northwestern Washington. Spacings were 8 x 8 ft (dense), 12 x 12 it (intermediate), and 16 x 16 ft (open). The effect of early thinning on growth and stem form was measured in 1982, 20 years after spacing treatment. There was negligible tree lean and sweep in open and intermediate stands except...

Ecotoxicological effects evoked in hydrophytes by leachates of invasive Acer negundo and autochthonous Alnus glutinosa fallen off leaves during their microbial decomposition.

Science.gov (United States)

Krevš, Alina; Darginavičienė, Jūratė; Gylytė, Brigita; Grigutytė, Reda; Jurkonienė, Sigita; Karitonas, Rolandas; Kučinskienė, Alė; Pakalnis, Romas; Sadauskas, Kazys; Vitkus, Rimantas; Manusadžianas, Levonas

2013-02-01

Throughout 90-day biodegradation under microaerobic conditions, invasive to Lithuania species boxelder maple (Acer negundo) leaves lost 1.5-fold more biomass than that of autochthonous black alder (Alnus glutinosa), releasing higher contents of N(tot), ammonium and generating higher BOD(7). Boxelder maple leaf leachates were characterized by higher total bacterial numbers and colony numbers of heterotrophic and cellulose-decomposing bacteria than those of black alder. The higher toxicity of A. negundo aqueous extracts and leachates to charophyte cell (Nitellopsis obtusa), the inhabitant of clean lakes, were manifested at mortality and membrane depolarization levels, while the effect on H(+)-ATPase activity in membrane preparations from the same algae was stronger in case of A. glutinosa. Duckweed (Lemna minor), a bioindicator of eutrophic waters, was more sensitive to leaf leachates of A. glutinosa. Fallen leaves and leaf litter leachates from invasive and native species of trees, which enter water body, affect differently microbial biodestruction and aquatic vegetation in freshwater systems. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effects of thinning and mixed plantations with Alnus cordata on growth and efficiency of common walnut (Juglans regia L.

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Giannini T

2009-01-01

Full Text Available Results about the effects of thinning and mixed plantations with Italian alder (Alnus cordata Loisel. on growth and efficiency of common walnut (Juglans regia L. plantations for wood production are reported. The study, carried out for six years on sixteen year old plantations, compared three theses: pure common walnut plantation (pure common walnut; 50% common walnut - 50% Italian alder plantation; 25% common walnut - 75% Italian alder plantation. Beyond annual surveys of girth at breast height, total height, stem volume and biomass, several variables, useful to describe canopy and foliage characteristics such as leaf area index (LAI, leaf biomass and photosynthetic active radiation below the canopy, were recorded. Data collected allowed to compare growth at individual and whole stand level, to calculate the net assimilation rate (NAR and to compare the growth efficiency of the three theses. Mixed plantations performed results significantly higher than the pure plantation in terms of growth, LAI and leaf biomass both before and after experimental thinning. With reference only to common walnut, growth in mixed plantations was higher than the pure plantation with differences ranging from +40% to +100%. More relevant differences among pure common walnut, 50% common walnut and 25% common walnut at canopy and foliage characteristics were observed, with LAI values of 1.07, 3.96 e 4.35 m2 m-2 respectively. Results accounted for a general positive effect of Italian alder as accessory tree species on growth and efficiency of mixed plantations, mainly due to the good performances induced in common walnut trees. Such performances were enabled by the good ecological integration between the two species and by the positive effects of N-fixing activity of Italian alder. Experimental thinning applied, although heavy, did not biased the dynamics observed before thinning both in pure and mixed plantations. In addition, they had positive effects on common walnut

A review of the characteristics of black alder (Alnus glutinosa (L.) Gaertn.) and their implications for silvicultural practices

NARCIS (Netherlands)

Claessens, H.; Oosterbaan, A.; Savill, P.; Rondeux, J.

2010-01-01

Black alder is a scattered, widespread and short-lived species that thrives in low-lying damp and riparian places. It has a use in flood control, stabilization of riverbanks and in functioning of the river ecosystems. To thrive, precipitation must exceed 1500 mm if access to groundwater is not

Vertebrate Herbivore Browsing on Neighboring Forage Species Increases the Growth and Dominance of Siberian Alder Across a Latitudinal Transect in Northern Alaska.

Science.gov (United States)

McNeill, E. M.; Ruess, R. W.

2017-12-01

Vertebrate herbivores strongly influence plant growth and architecture, biogeochemical cycling, and successional dynamics in boreal and arctic ecosystems. One of the most notable impacts of vertebrate herbivory is on the growth and spread of alder, a chemically-defended, N-fixing shrub whose distribution in the Alaskan arctic has expanded dramatically over the past 60 years. Although herbivore effects on thin-leaf alder are well described for interior Alaskan floodplains, no work has been conducted on the effects of herbivores on Siberian alder (Alnus viridis spp fruticosa), despite the increasing importance of this species to high latitude ecosystems. We characterized browsing by snowshoe hares, moose, and willow ptarmigan on dominant shrub species across topo-edaphic sequences within 5 ecoregions along a 600 km latitudinal transect extending from interior Alaska to the North Slope. Ptarmigan browsed wind-blown lowland and alpine sites devoid of trees in all regions; moose browsed predominantly willow species in hardwood and mixed forests and were absent north of the Brooks Range; snowshoe hares selected habitats and forage based on their local density and vulnerability to predators. Browsing intensity on Siberian alder was either undetectable or low, limited primarily to hare browsing on young ramets in the northern boreal forest where hare density relative to forage availability is highest. Overall, alder height growth was positively correlated with levels of herbivory on competing shrub species. Our data support the hypothesis that vertebrate herbivore browsing is indirectly augmenting the growth, dominance, and possible spread of Siberian alder throughout its northern Alaskan range. Given the potential high rates of N-fixation inputs by Siberian alder, we believe herbivores are also having strong indirect effects on biogeochemical cycling and possibly C storage in these landscapes.

Accumulation of 137Cs and 90Sr in wood and bark of various types of oak and black alder plantings

International Nuclear Information System (INIS)

Perevolotskij, A.N.; Bulavik, I.M.; Perevolotskaya, T.V.; Paskrobko, L.A.; Andrush, S.N.

2008-01-01

Results of the evaluation of the influence of types of habitat edaphic conditions on 137Cs and 90Sr transition coefficients and their accumulation by wood and bark of English oak (Quercus robur L.) and black alder (Alnus glutinosa (L.) Gaertn) were presented. There was observed the particular influence of edaphic conditions on 137Cs and 90Sr accumulation by wood and bark of English oak. Lowering of 137Cs transition coefficients for the studied elements of phytomass was noted in the conditions of soil fertility increasing. Influence of soil moistening on 137Cs transition into wood and bark of oak trees was stated only in wood-sorrel and glague types of forests. Differences in accumulation of 90Sr by wood and bark of English oak in the studied range of edaphotopes were not proved. There was not found any differences in accumulation of both radionuclides by black alder trees in the typical for them edaphic conditions

Comparative phytosociological investigation of subalpine alder thickets in southwestern Alaska and the North Pacific

Science.gov (United States)

Talbot, Stephen S.; Talbot, Sandra L.; Daniëls, F. J. A.

2005-01-01

We present the first vegetation analysis of subalpine alder (Alnus viridis) thickets in southwestern Alaska. The data are primarily from mesic, hilly and mountainous sites ranging from the westernmost tip of the Alaska Peninsula to the northern Kenai Peninsula, spanning 1,000 km on an E–W gradient and 700 km on a N–S gradient. 127 relevés from 18 sites represent the range of structural and compositional variation in the matrix of vegetation and landform diversity. Data were analyzed by multivariate and traditional Braun-Blanquet methods. One association is distinguished, Sambuco racemosi-Alnetum viridis ass. nov. with three new subassociations, oplopanacetosum horridi, typicum, and rubetosum spectabilis with the latter subdivided into four variants. These phytocoena are well-differentiated, although they form a syntaxonomical continuum. The composition and structure of these communities are described and interpreted in relation to complex environmental factors; these are analyzed using Jancey's ranking on F-values. Community composition is primarily related to elevation, longitude, soil moisture, and latitude. Phytogeographic comparison of southwestern Alaska alder communities with those elsewhere in the North Pacific suggests a close floristic relationship to those of southcentral, southeastern Alaska and coastal British Columbia, Canada. All these communities belong to the same association, while those of the eastern and southern parts of the Kamchatka Peninsula, Russia belong to a different association. Syntaxonomy of the 4 major communities is discussed. Within the Northern Hemisphere, vascular plant species of southwestern Alaska alder thickets primarily occur in East Asia and North America, 36 %; while 26 % are circumpolar, and 22 % are restricted to North America. From a latitudinal perspective, the distribution of vascular plant species within these alder thickets peaks in the high-subarctic, low-subarctic, and temperate latitudinal zones, with low

Models of sustainable use of alder (Alnus acuminate Kunth hillside area in forest mist

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Pacheco-Agudo Edilberto

2016-05-01

Full Text Available Timber extractions non planned affect negatively in the reduction of forest cover, proper management and planned with minor extractions preserve the natural production allow for longer and sustainable forms a stand to benefit local populations and the same ecosystem. In the basin of Acero Marca has two stands Alnus acuminata that they are extracted continuously. With the purpose of planning the extraction of timber resourses were constructed and evaluated matrix models sustainable harvest of this species on the basis of structures of age. For this, two old structures we worked following a dendrochronological analysis and demographic model of the forestall mass, from making local information by transectos Gentry. According to the demographic model, the potential regression evidences significant differences (p 1 and could be the most appropriate for a planned extraction becoming sustainable over time. The second structure of age proved extremely sensitive to any change. To use the matrix models is not a simple path of going over. In spite of the results, the matrix models joined to ample experience of the observer would be able to present proposals of sustainable handling of the forestal resources.

The climate warming effect of a fen peat meadow with fluctuating water table is reduced by young alder trees

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V. Huth

2018-03-01

Full Text Available Black alder (Alnus glutinosa (L. Gaertn. occurs naturally in temperate marshes and in minerotrophic peatlands and is also suitable for paludiculture - the cultivation of biomass on wet or rewetted peatland. We investigated the effect of a newly established black alder plantation on the greenhouse gas (GHG balance of a degraded fen in north-eastern Germany over a two-year period (August 2010–August 2012. We compared the alder plantation (Awet with an extensively used meadow (Mwet and a drier reference meadow (Mmoist. GHG fluxes were measured monthly to bi-monthly using the closed chamber method. Our results show that Awet was a slight net GHG (in CO2-eq sink of 3.4 ± 1.7 t ha-1 yr-1, Mwet was a moderate net GHG source of 9.6 ± 1.2 t ha 1 yr-1, and Mmoist was a strong net GHG source of 24.5 ± 1.6 t ha-1 yr-1. This was mainly driven by CO2 uptake at the two very moist (wet sites and by high CO2 release at the drier reference site. Awet was a larger CO2 sink than Mwet, probably due to additional CO2 uptake by the alder stand at Awet and carbon export in plant material harvested from Mwet. All sites were significant CH4 sources. Substantial CH4 emission peaks were observed at all sites following extraordinarily heavy precipitation during the summer of 2011, which accounted for up to 70 % of the accumulated two-year CH4 emissions. However, the Awet site generally emitted less CH4, possibly due to the effective oxygen transport mechanism in black alders. N2O emissions were negligible at all three sites. Our results indicate that the GHG balances of formerly drained fens benefit in the short term from planting of black alders, mostly due to reduced CH4 emissions. This study highlights the importance of acknowledging extreme precipitation events and groundwater fluctuations for the derivation of reliable GHG emission factors.

Role of river flow and sediment mobilization in riparian alder establishment along a bedrock-gravel river, South Fork Eel River, California

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Jablkowski, P.; Johnson, E. A.; Martin, Y. E.

2017-10-01

Climatic, hydraulics, hydrologic, and fluvial geomorphic processes are the main drivers of riparian white alder (Alnus rhombifolia Nutt.) distribution in northern California. The Mediterranean climate and canyon bound, bedrock-gravel morphology of the South Fork Eel have a distinct effect on these processes. White alder seeds are preferentially deposited on river bars where river hydraulics create eddies coinciding with the downstream part of riffles and the upstream part of pools. Seeds are generally deposited below bankfull elevations by the descending hydrograph during the spring season in this Mediterranean climate. For successful germination and establishment, the seeds must be deposited at a location such that they are not remobilized by late spring flows. The summer establishment period is defined from the date of seed deposition and germination to the fall/winter date of river sediment mobilization. Seedling root growth rate decreases exponentially with decreasing water potential. However, seedlings are shown not to be generally limited by water availability at the elevations they are most commonly deposited. The establishment of white alder seedlings following the first summer will therefore depend on their ability to resist fall/winter high flows. The method proposed here compares the predicted rooting depth to predicted sediment scour rates. The length of the establishment period rather than water availability determines final seedling rooting depth. Over the past 40 years, very few years had establishment periods that were long enough or had fast enough alder growth rates to survive winter floods that often scour deeper than the total root length. The low survival of seedlings in the first autumn season following germination is believed to be a principal reason for the missing age classes often found in alder distributions along rivers.

Ecotoxicity effects triggered in aquatic organisms by invasive Acer negundo and native Alnus glutinosa leaf leachates obtained in the process of aerobic decomposition.

Science.gov (United States)

Manusadžianas, Levonas; Darginavičienė, Jūratė; Gylytė, Brigita; Jurkonienė, Sigita; Krevš, Alina; Kučinskienė, Alė; Mačkinaitė, Rimutė; Pakalnis, Romas; Sadauskas, Kazys; Sendžikaitė, Jūratė; Vitkus, Rimantas

2014-10-15

The replacement of autochthonous tree species by invasive ones in coastal zones of freshwater bodies induces additional alteration of hydrochemical and microbiological characteristics due to decomposition of fallen leaves of non-indigenous species, which can lead to ecotoxic response of the littoral biota. Leaves of invasive to Lithuania boxelder maple (Acer negundo) and autochthonous black alder (Alnus glutinosa) lost more than half of biomass and released stable amount of DOC (60-70 mg/L) throughout 90-day mesocosm experiment under aerobic conditions. This, along with the relatively small BOD7 values detected after some variation within the first month confirms effective biodegradation by fungi and bacteria. The ambient water was more enriched with different forms of N and P by decomposing boxelder maple than by alder leaves. During the first month, both leachates were more toxic to charophyte (Nitellopsis obtusa) at mortality and membrane depolarization levels, while later to two crustacean species. Biomarker response, H(+)-ATPase activity in membrane preparations from N. obtusa, was stronger for A. negundo. Generally, boxelder maple leaf leachates were more toxic to tested hydrobionts and this coincides with previous study on leaves of the same pair of tree species conducted under microaerobic conditions (Krevš et al., 2013). Copyright © 2014 Elsevier B.V. All rights reserved.

Hourly pattern of allergenic alder and birch pollen concentrations in the air: Spatial differentiation and the effect of meteorological conditions

Science.gov (United States)

Borycka, K.; Kasprzyk, I.

2018-06-01

In temperate climate widespread alder and birch are an important source of strong aeroallergens. The diurnal pattern of airborne pollen concentrations depends on the rhythm of pollen release from anthers as well as weather conditions, convection air currents, long-distance transport, pollen trap location and local vegetation. The aim of the study was to present a diurnal pattern of Alnus (alder) and Betula (birch) pollen concentrations in the air in a horizontal and vertical gradient and examine the weather parameters that had the greatest impact on the pattern. The study was conducted in Rzeszów City, southeast Poland over three years. Pollen grains were collected using a Hirst volumetric spore trap at three sampling points: two at 12 m the agl, and one at 1.5 m agl. Data were analysed using circular statistics and a nonlinear function. For alder, three models of hourly patterns were elaborated and the most common presented early morning minimum and early afternoon maximum. For birch, the most common model has one peak at night and a marked decrease in concentrations in early morning, although a second model has peak during early afternoon. A model with 3 peaks is much less common. These models are characteristic for warm temperate climate regions, where alders and birches are common. The diurnal patterns did not depend on the localization of traps or proximity of the pollen source, although these factors influenced the hourly concentrations, with higher values observed at roof level. Significant relationships between the hourly pollen counts and meteorological parameters were observed only for alder. Three incidents of increasing birch pollen concentrations were observed during the first two hours of precipitation and linked to a convection effect. Unstable weather conditions caused by air convection might strongly modify the circadian pattern and cause the nightly peaks concentrations. The general results are that people suffering from allergies may be exposed

Solar ultraviolet radiation alters alder and birch litter chemistry that in turn affects decomposers and soil respiration.

Science.gov (United States)

Kotilainen, Titta; Haimi, Jari; Tegelberg, Riitta; Julkunen-Tiitto, Riitta; Vapaavuori, Elina; Aphalo, Pedro Jose

2009-10-01

Solar ultraviolet (UV)-A and UV-B radiation were excluded from branches of grey alder (Alnus incana) and white birch (Betula pubescens) trees in a field experiment. Leaf litter collected from these trees was used in microcosm experiments under laboratory conditions. The aim was to evaluate the effects of the different UV treatments on litter chemical quality (phenolic compounds, C, N and lignin) and the subsequent effects of these changes on soil fauna and decomposition processes. We measured the decomposition rate of litter, growth of woodlice (Porcellio scaber), soil microbial respiration and abundance of nematodes and enchytraeid worms. In addition, the chemical quality of woodlice feces was analyzed. The exclusion of both UV-A and UV-B had several effects on litter chemistry. Exclusion of UV-B radiation decreased the C content in litter in both tree species. In alder litter, UV exclusion affected concentration of phenolic groups variably, whereas in birch litter there were no significant differences in phenolic compounds. Moreover, further effects on microbial respiration and chemical quality of woodlice feces were apparent. In both tree species, microbial CO(2) evolution was lower in soil with litter produced under exclusion of both UV-A and UV-B radiation when compared to soil with control litter. The N content was higher in the feces of woodlice eating alder litter produced under exclusion of both UV-A and UV-B compared to the control. In addition, there were small changes in the concentration of individual phenolic compounds analyzed from woodlice feces. Our results demonstrate that both UV-A and UV-B alter litter chemistry which in turn affects decomposition processes.

Survival and growth for pubescent birch, pendula birch and common alder growing on farmland areas; Oeverlevnad och tillvaext hos glasbjoerk, vaartbjoerk och klibbal planterade paa aakermark

Energy Technology Data Exchange (ETDEWEB)

Johansson, Tord

2000-07-01

Pendula birches (Betula pendula Roth) and pubescent birches (Betula pubescens Ehrh.) were planted on former farmland. Before planting, the ground was harrowed or the ground was sprayed with terbuthylazine. Tree shelters were used as protection against weeds, voles and wild habitat. Birches treated with terbuthylazine showed the lowest survival. Birches growing in tree shelters were tallest and those growing on spots treated with terbuthylazine were smallest. The diameter at 0.1 m did not differ in a statistically significant way between the treatments. In another experiment with different herbicides, common alder (Alnus glutinosa (L.) Gaertn.) and pendula birch (Betula pendula Roth) were planted on former farmland that had been treated with glyphosate, terbuthylazine and propyzamide or after ground had been harrowed or not treated. In the study on herbicide-treated plants, birch had the highest plant survival. Mostly, species treated with glyphosate were thicker than species treated in other ways. Both species appeared sensitive to terbuthylazine, but not to glyphosate. Birch was not sensitive for propyzamide in opposite to alder. Some practical recommendations concerning afforestation of former farmland, especially weeding, are given.

Red alder potential in Alaska

Science.gov (United States)

Allen Brackley; David Nicholls; Mike Hannan

2010-01-01

Over the past several decades, red alder has established itself as a commercially important species in the Pacific Northwest. Once considered a weed species, red alder now commands respect within many markets, including furniture, architectural millwork, and other secondary manufactured products. Although red alder's natural range extends to southeast Alaska, an...

Influence of roadside pollution on the phylloplane microbial community of Alnus nepalensis (Betulaceae)

International Nuclear Information System (INIS)

Joshi, S. R.

2008-01-01

The North Eastern region of India is undergoing industrial development at a faster rate than expected. Roads form the main system of transportation and communication owing to the hilly topography of the region. Automobiles discharge a number of gaseous and trace metal contaminants. Human activities like stone grinding, road construction and sand milling also increase the atmospheric dust and heavy metal contaminant level. These contaminants get settled on leaf surfaces at roadsides and enter in contact with phylloplane microorganisms. This study compares microorganisms on leaf surfaces of alder (Alnus nepalensis (Betulaceae)) on roadside and non-roadside environments. Two sites dominated by alder were selected. One at a busy road intersection on the National Highway no. 44 in Shillong with high traffic density (8000-9000 heavy vehicles/day), taken as the polluted site and the other one in a forest approximately 500 m away from the roadside considered as the unpolluted site. Analysis of phylloplane microorganisms, lead, zinc, copper, cadmium and sulphur was carried out from leaves. The bacterial population was higher at the unpolluted site. Bacterial population showed a significant negative correlation with lead, zinc, copper, cadmium and sulphur. Similarly, fungal population was higher at the unpolluted site. A total of 29 fungal species were isolated from the phylloplane of A. nepalensis (polluted site 16 species; unpolluted site 28 species). Some fungal forms like Mortierella sp., Fusarium oxysporum and Aureobasidium pollulans were dominant in the polluted site. Numbers of phylloplane fungi and bacteria were significantly reduced in the polluted site. The correlation coefficient indicated a detrimental effect of metals like lead, zinc, copper, cadmium and sulphur on the microbial community of leaf surfaces. The specificity of certain fungi to the unpolluted site may be attributed to their sensitivity to pollution. The predominance of Aureobasidium pollulans

Edge-glued panels from Alaska hardwoods: retail manager perspectives

Science.gov (United States)

David Nicholls; Matthew Bumgardner; Valerie Barber

2010-01-01

In Alaska, red alder (Alnus rubra Bong.) and paper birch (Betula papyrifera Marsh.) are both lesser-known hardwoods grown, harvested, and manufactured into appearance products, with potential for increased utilization. The production of edgeglued panels from red alder and paper birch offers one expansion opportunity for wood...

Diversity-Oriented Approaches to Polycyclics and Bioinspired Molecules via the Diels-Alder Strategy: Green Chemistry, Synthetic Economy, and Beyond.

Science.gov (United States)

Kotha, Sambasivarao; Chavan, Arjun S; Goyal, Deepti

2015-05-11

We describe diverse approaches to various dienes and their utilization in the Diels-Alder reaction to produce a variety of polycycles. The dienes covered here are prepared by simple alkylation reaction or via the Claisen rearrangement or by enyne metathesis of alkyne or enyne building blocks. Here, we have also included the Diels-Alder chemistry of dendralenes, a higher analog of cross-conjugated dienes. The present article is inclusive of o-xylylene derivatives that are generated in situ starting with benzosultine or benzosulfone derivatives. The Diels-Alder reaction of these dienes with various dienophiles gave diverse polycyclic systems and biologically important targets.

Utilization and management of alder.

Science.gov (United States)

David G. Briggs; Dean S. DeBell; William A. Atkinson

1978-01-01

In the Pacific Northwest and British Columbia, red alder often grows on forest lands following natural or man-caused disturbances. Frequently ignored as a pest or weed, many alder stands have developed to the point where important utilization and management questions are being asked. It is recognized that alder is a fast growing species, and that its rapid early growth...

Effect of aqueous extracts of black alder (Alnus glutinosa (LINNAEUS, 1753 GAERTNER, 1791 and elder (Sambucus nigra LINNAEUS, 1753 on the occurrence of Brevicoryne brassicae LINNAEUS, 1758 (Hemiptera, Aphidoidea, its parasitoid Diaeretiella rapae (M’INTOSH, 1855 (Hymenoptera, Ichneumonoidea and predatory Syrphidae on white cabbage

Directory of Open Access Journals (Sweden)

Jankowska Beata

2016-06-01

Full Text Available The insecticidal and antifeedant effects of aqueous extracts from two common plants (black alder Alnus glutinosa and elder Sambucus nigra on the occurrence of Brevicoryne brassicae, its parasitoid Diaeretiella rapae and predatory Syrphidae on white cabbage were investigated in 2008-2009. Both extracts reduced the number of cabbage aphids, although the Sambucus nigra extract proved to have a better effect. Differences were seen both in the numbers of winged aphids settling on plants and in the overall numbers of aphids on plants during the entire season. There were no significant differences in the degree of parasitization by Diaeretiella rapae in the three experimental combinations. Eight species of Syrphidae were found in the Brevicoryne brassicae colonies: Episyrphus balteatus, Sphaerophoria scripta, S. rueppelli, S. menthastri, Eupeodes corollae, Scaeva pyrastri, Scaeva selenitica and Syrphus vitripennis. The dominant species was Episyrphus balteatus. The largest numbers of syrphid larvae and pupae were collected from cabbage aphid colonies on the control plants. Smaller numbers were recorded on the plot where the cabbages were sprayed with the Sambucus nigra extract. The results of this study indicate that botanical insecticides based on S. nigra have the potential to be incorporated into control programmes for the cabbage aphid.

Managing young upland forests in southeast Alaska for wood products, wildlife, aquatic resources, and fishes: problem analysis and study plan.

Science.gov (United States)

Mark S. Wipfli; Robert L. Deal; Paul E. Hennon; Adelaide C. Johnson; Toni L. de Santo; Thomas A. Hanley; Mark E. Schultz; Mason D. Bryant; Richard T. Edwards; Ewa H. Orlikowska; Takashi Gomi

2002-01-01

Red alder (Alnus rubra Bong.) appears to influence the productivity of young-growth conifer forests and affect the major resources (timber, wildlife, and fisheries) of forested ecosystems in southeast Alaska. We propose an integrated approach to understanding how alder influences trophic links and processes in young-growth ecosystems. The presence...

Red alder: a state of knowledge.

Science.gov (United States)

Robert L. Deal; Constance A. Harrington

2006-01-01

In March 23-25, 2005, an international symposium on red alder was held at the University of Washington Center for Urban Horticulture in Seattle, WA. The symposium was entitled "Red alder: A State of Knowledge" and brought together regional experts to critically examine the economic, ecological and social values of red alder. The primary goal of the symposium...

Development of Green and Sustainable Chemical Reactions

DEFF Research Database (Denmark)

Taarning, Esben

Abstract This thesis entitled Development of Green and Sustainable Chemical Reactions is divided into six chapters involving topics and projects related to green and sustainable chemistry. The chapters can be read independently, however a few concepts and some background information is introduced...... as well as the possibility for establishing a renewable chemical industry is discussed. The development of a procedure for using unsaturated aldehydes as olefin synthons in the Diels- Alder reaction is described in chapter three. This procedure affords good yields of the desired Diels- Alder adducts...... in chapter one and two which can be helpful to know when reading the subsequent chapters. The first chapter is an introduction into the fundamentals of green and sustainable chemistry. The second chapter gives an overview of some of the most promising methods to produce value added chemicals from biomass...

Promotion of adventitious root formation of difficult-to-root hardwood tree species

Science.gov (United States)

Paula M. Pijut; Keith E. Woeste; Charles H. Michler

2011-01-01

North American hardwood tree species, such as alder (Alnus spp.), ash (Fraxinus spp.), basswood (Tilia spp.), beech (Fagus spp.), birch (Betula spp.), black cherry (Prunus seratina), black walnut (Juglans nigra), black willow (...

Volume tables for red alder.

Science.gov (United States)

Floyd A. Johnson; R. M. Kallander; Paul G. Lauterbach

1949-01-01

The increasing importance of red alder as a commercial species in the Pacific Northwest has prompted the three agencies listed above to pool their tree measurement data for the construction of standard regional red alder volume tables. The tables included here were based on trees from a variety of sites and form classes. Approximately one quarter of the total number of...

Effects of Alder Mine on the Water, Sediments, and Benthic Macroinvertebrates of Alder Creek, 1998 Annual Report.

Energy Technology Data Exchange (ETDEWEB)

Peplow, Dan

1999-05-28

The Alder Mine, an abandoned gold, silver, copper, and zinc mine in Okanogan County, Washington, produces heavy metal-laden effluent that affects the quality of water in a tributary of the Methow River. The annual mass loading of heavy metals from two audits at the Alder Mine was estimated to exceed 11,000 kg per year. In this study, water samples from stations along Alder Creek were assayed for heavy metals by ICP-AES and were found to exceed Washington State's acute freshwater criteria for cadmium (Cd), copper (Cu), selenium (Se), and zinc (Zn).

Bioactive Pentacyclic Triterpene Ester Derivatives from Alnus viridis ssp. viridis Bark.

Science.gov (United States)

Novakovic, Miroslav; Nikodinovic-Runic, Jasmina; Veselinovic, Jovana; Ilic-Tomic, Tatjana; Vidakovic, Vera; Tesevic, Vele; Milosavljevic, Slobodan

2017-05-26

Seven derivatives of pentacyclic triterpene acids (1-7) were isolated from the bark of Alnus viridis ssp. viridis using a combination of column chromatography and semipreparative HPLC. Compounds 1-3, 6, and 7 were determined to be new after spectroscopic data interpretation and were assigned as 27-hydroxyalphitolic acid derivatives (1-3), a 27-hydroxybetulinic acid derivative (6), and a 3-epi-maslinic acid derivative (7), respectively. Pentacyclic triterpenoids with a C-27 hydroxymethyl group have been found in species of the genus Alnus for the first time. These compounds were subjected to cytotoxicity testing against a number of cancer cell lines. Also, selected pentacyclic triterpenoids were selected as potential inhibitors of topoisomerases I and IIα for an in silico investigation.

The pentadehydro-Diels-Alder reaction.

Science.gov (United States)

Wang, Teng; Naredla, Rajasekhar Reddy; Thompson, Severin K; Hoye, Thomas R

2016-04-28

In the classic Diels-Alder [4 + 2] cycloaddition reaction, the overall degree of unsaturation (or oxidation state) of the 4π (diene) and 2π (dienophile) pairs of reactants dictates the oxidation state of the newly formed six-membered carbocycle. For example, in the classic Diels-Alder reaction, butadiene and ethylene combine to produce cyclohexene. More recent developments include variants in which the number of hydrogen atoms in the reactant pair and in the resulting product is reduced by, for example, four in the tetradehydro-Diels-Alder (TDDA) and by six in the hexadehydro-Diels-Alder (HDDA) reactions. Any oxidation state higher than tetradehydro (that is, lacking more than four hydrogens) leads to the production of a reactive intermediate that is more highly oxidized than benzene. This increases the power of the overall process substantially, because trapping of the reactive intermediate can be used to increase the structural complexity of the final product in a controllable and versatile manner. Here we report an unprecedented overall 4π + 2π cycloaddition reaction that generates a different, highly reactive intermediate known as an α,3-dehydrotoluene. This species is in the same oxidation state as a benzyne. Like benzynes, α,3-dehydrotoluenes can be captured by various trapping agents to produce structurally diverse products that are complementary to those arising from the HDDA process. We call this new cycloisomerization process a pentadehydro-Diels-Alder (PDDA) reaction-a nomenclature chosen for chemical taxonomic reasons rather than mechanistic ones. In addition to alkynes, nitriles (RC≡N), although non-participants in aza-HDDA reactions, readily function as the 2π component in PDDA cyclizations to produce, via trapping of the α,3-(5-aza)dehydrotoluene intermediates, pyridine-containing products.

Application of the aza-Diels-Alder reaction in the synthesis of natural products.

Science.gov (United States)

Cao, Min-Hui; Green, Nicholas J; Xu, Sheng-Zhen

2017-04-11

The Diels-Alder reaction that involves a nitrogen atom in the diene or dienophile is termed the aza-Diels-Alder reaction. As well as the powerful all-carbon Diels-Alder reaction, the aza-Diels-Alder reaction has also played an important role in the total synthesis of natural products. Herein, we review various natural products using an aza-Diels-Alder reaction as a key step to their total synthesis, and divide the syntheses into inter- and intra-molecular aza-Diels-Alder reactions and a retro-aza-Diels-Alder reaction. Inter- and intra-molecular aza-Diels-Alder reactions involve an imine as an electron deficient dienophile and an imine as an electron deficient azadiene. The significance of the aza-Diels-Alder reaction for the construction of a six-membered ring containing nitrogen is tremendous, but the development of asymmetric, in particular catalytic enantioselective intramolecular aza-Diels-Alder reaction in the total synthesis of natural products remains highly challenging, and will no doubt see enormous advances in the future.

16S rRNA as molecular marker in ecology of Frankia

NARCIS (Netherlands)

Hahn, D.

1990-01-01

The research described in this thesis focusses on the role of biotic factors encountered with the establishment of the symbiosis between black alder plants ( Alnus glutinosa ) and introduced Frankia strains. A selection of

The impact of a pulsing groundwater table on greenhouse gas emissions in riparian grey alder stands.

Science.gov (United States)

Mander, Ülo; Maddison, Martin; Soosaar, Kaido; Teemusk, Alar; Kanal, Arno; Uri, Veiko; Truu, Jaak

2015-02-01

Floods control greenhouse gas (GHG) emissions in floodplains; however, there is a lack of data on the impact of short-term events on emissions. We studied the short-term effect of changing groundwater (GW) depth on the emission of (GHG) carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) in two riparian grey alder (Alnus incana) stands of different age in Kambja, southern Estonia, using the opaque static chamber (five replicates in each site) and gas chromatography methods. The average carbon and total nitrogen content in the soil of the old alder (OA) stand was significantly higher than in the young alder (YA) stand. In both stands, one part was chosen for water table manipulation (Manip) and another remained unchanged with a stable and deeper GW table. Groundwater table manipulation (flooding) significantly increases CH4 emission (average: YA-Dry 468, YA-Manip 8,374, OA-Dry 468, OA-Manip 4,187 μg C m(-2) h(-1)) and decreases both CO2 (average: OA-Dry 138, OA-Manip 80 mg C m(-2) h(-1)) and N2O emissions (average: OA-Dry 23.1, OA-Manip 11.8 μg N m(-2) h(-1)) in OA sites. There was no significant difference in CO2 and CH4 emissions between the OA and YA sites, whereas in OA sites with higher N concentration in the soil, the N2O emission was significantly higher than at the YA sites. The relative CO2 and CH4 emissions (the soil C stock-related share of gaseous losses) were higher in manipulated plots showing the highest values in the YA-Manip plot (0.03 and 0.0030 % C day(-1), respectively). The soil N stock-related N2O emission was very low achieving 0.000019 % N day(-1) in the OA-Dry plot. Methane emission shows a negative correlation with GW, whereas the 20 cm depth is a significant limit below which most of the produced CH4 is oxidized. In terms of CO2 and N2O, the deeper GW table significantly increases emission. In riparian zones of headwater streams, the short-term floods (e.g. those driven by extreme climate events) may significantly enhance

Spatial variation in population dynamics of Sitka mice in floodplain forests.

Science.gov (United States)

T.A. Hanley; J.C. Barnard

1999-01-01

Population dynamics and demography of the Sitka mouse, Peromyscus keeni sitkensis, were studied by mark-recapture live-trapping over a 4-year period in four floodplain and upland forest habitats: old-growth Sitka spruce (Picea sitchensis) floodplain; red alder (Alnus rubra) floodplain; beaver-pond...

Phylloplane bacteria increase the negative impact of food limitation on insect fitness

NARCIS (Netherlands)

Olson, Grant L.; Myers, Judith H.; Hemerik, Lia; Cory, Jenny S.

2017-01-01

1. When populations of herbivorous insects increase in density, they can alter the quantity or quality of their food. The impacts of diet-related stressors on insect fitness have been investigated singly, but not simultaneously. 2. Foliage quantity and quality of red alder, Alnus rubra, were

Growth and N2 fixation in an Alnus hirsuta (Turcz.) var. sibirica stand ...

Indian Academy of Sciences (India)

2013-10-01

Oct 1, 2013 ... remains high, although varying in summer, decreasing in autumn, and .... 10% acetylene in air within glass containers of 200 mL capacity. ...... elevated CO2 and nitrogen availability on nodulation of Alnus hirsuta Turcz.

Solvent Effects in Asymmetric Hetero Diels-Alder and Ene Reactions

DEFF Research Database (Denmark)

Johannsen, Mogens; Jørgensen, Karl Anker

1996-01-01

The use of polar solvents such as nitromethane or 2-nitropropane leads to a significant improvement of the catalytic properties of a cationic copper-Lewis acid in the hetero Diels-Alder reaction of alkyl glyoxylates with dienes; The scope of a newly developed copper(II)-bisoxazoline catalyst...... for the hetero Diels-Alder reaction is demonstrated by the reaction of different dienes with alkyl glyoxylates in nitroalkane solvents with the formation of the hetero Diels-Alder adduct in high enantiomeric excess as the major product. The synthetic application of the reaction is exemplified by an improved...

Influence of roadside pollution on the phylloplane microbial community of Alnus nepalensis (Betulaceae

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S.R Joshi

2008-09-01

Full Text Available The North Eastern region of India is undergoing industrial development at a faster rate than expected. Roads form the main system of transportation and communication owing to the hilly topography of the region. Automobiles discharge a number of gaseous and trace metal contaminants. Human activities like stone grinding, road construction and sand milling also increase the atmospheric dust and heavy metal contaminant level. These contaminants get settled on leaf surfaces at roadsides and enter in contact with phylloplane microorganisms. This study compares microorganisms on leaf surfaces of alder (Alnus nepalensis (Betulaceae on roadside and non-roadside environments. Two sites dominated by alder were selected. One at a busy road intersection on the National Highway no. 44 in Shillong with high traffic density (8 000-9 000 heavy vehicles/day, taken as the polluted site and the other one in a forest approximately 500 m away from the roadside considered as the unpolluted site. Analysis of phylloplane microorganisms, lead, zinc, copper, cadmium and sulphur was carried out from leaves. The bacterial population was higher at the unpolluted site. Bacterial population showed a significant negative correlation with lead, zinc, copper, cadmium and sulphur. Similarly, fungal population was higher at the unpolluted site. A total of 29 fungal species were isolated from the phylloplane of A. nepalensis (polluted site 16 species; unpolluted site 28 species. Some fungal forms like Mortierella sp., Fusarium oxysporum and Aureobasidium pollulans were dominant in the polluted site. Numbers of phylloplane fungi and bacteria were significantly reduced in the polluted site. The correlation coefficient indicated a detrimental effect of metals like lead, zinc, copper, cadmium and sulphur on the microbial community of leaf surfaces. The specificity of certain fungi to the unpolluted site may be attributed to their sensitivity to pollution. The predominance of

The Diels Alder/retro-Diels Alder concept on solid support : a study of the scope, limitations and conceivable applications as a traceless thermocleavable linker

NARCIS (Netherlands)

Gieling, Reinerus Gerardus

2003-01-01

This thesis deals with the conceivable transfer of the Diels Alder/retro-Diels Alder concept to the solid phase in order to broaden the scope of the methodology to a combinatorial level. In addition, based on this methodology the development of a traceless thermocleavable linking system for

Stepwise radical cation Diels-Alder reaction via multiple pathways.

Science.gov (United States)

Shimizu, Ryo; Okada, Yohei; Chiba, Kazuhiro

2018-01-01

Herein we disclose the radical cation Diels-Alder reaction of aryl vinyl ethers by electrocatalysis, which is triggered by an oxidative SET process. The reaction clearly proceeds in a stepwise fashion, which is a rare mechanism in this class. We also found that two distinctive pathways, including "direct" and "indirect", are possible to construct the Diels-Alder adduct.

Aliso en Simbiosis Dual con Frankia y Endomicorrizas y Respuesta a Boro en un Andisol Alder in Dual Symbiosis whith Frankia and Endomycorrhizae and Response at Boron in an Andisol

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Marisol Medina Sierra

2012-06-01

Full Text Available Resumen. Se evaluó la respuesta del aliso (Alnus acuminata Kunth a la inoculación dual con cepas de Frankia spp. y de hongos endomicorrizógenos con dos niveles de boro (B (0,3 y 0,6 mg kg-1 suelo y la aplicación de nitrógeno (N (40 kg ha-1, fósforo (P (30 mg kg-1 suelo y un control sin inoculación ni elementos químicos. Se empleó un diseño completamente aleatorizado, con 41 tratamientos y 20 repeticiones. Para el análisis estadístico de componentes principales se empleó el programa Multibiplot. Las variables respuesta correspondieron a la biomasa seca aérea y sus contenidos de N, P, Calcio (Ca y cenizas (cen. Se encontró que los tratamientos de P y N y las cepas nativas de Frankia spp. (UdeA902, UdeA904 y CUNMS502 combinados con hongos micorrizógenos (UdeA1905 y Glomus fistulosum respectivamente, favorecieron el rendimiento y contenido de N del aliso. La aplicación de B en algunos casos mejoró el rendimiento y en otros lo afectó negativamente; pero potenció la respuesta de algunas inoculaciones especialmente cuando estuvo presente G. fistulosum aún en el caso de estar acompañado de la cepa de Frankia (CUNMS502. Esta cepa, que presentó bajo rendimiento en otros tratamientos, se vio favorecida notablemente con la adición de B. La inoculación dual es efectiva para favorecer el manejo forestal del aliso siempre y cuando se haga la selección adecuada de las cepas, lo cual puede además condicionar la respuesta a algunos nutrientes como en el caso del B.Abstract. It was evaluated the response of alder (Alnus acuminata Kunth to the dual inoculation of strains of Frankia spp. and endomycorrhizal fungi with two levels of boron (B (0.3 and 0.6 mg kg-1 soil and the application of nitrogen (N (40 kg ha-1, phosphorus (P (30 mg kg-1 soil and a control without inoculation or chemical elements. The experimental design was completely randomized; it was composed kg-1of 41 treatments and 20 replications. The statistical analysis consisted

Regional and landscape-scale variability of Landsat-observed vegetation dynamics in northwest Siberian tundra

International Nuclear Information System (INIS)

Frost, Gerald V; Epstein, Howard E; Walker, Donald A

2014-01-01

Widespread increases in Arctic tundra productivity have been documented for decades using coarse-scale satellite observations, but finer-scale observations indicate that changes have been very uneven, with a high degree of landscape- and regional-scale heterogeneity. Here we analyze time-series of the Normalized Difference Vegetation Index (NDVI) observed by Landsat (1984–2012), to assess landscape- and regional-scale variability of tundra vegetation dynamics in the northwest Siberian Low Arctic, a little-studied region with varied soils, landscape histories, and permafrost attributes. We also estimate spatio-temporal rates of land-cover change associated with expansion of tall alder (Alnus) shrublands, by integrating Landsat time-series with very-high-resolution imagery dating to the mid-1960s. We compiled Landsat time-series for eleven widely-distributed landscapes, and performed linear regression of NDVI values on a per-pixel basis. We found positive net NDVI trends (‘greening’) in nine of eleven landscapes. Net greening occurred in alder shrublands in all landscapes, and strong greening tended to correspond to shrublands that developed since the 1960s. Much of the spatial variability of greening within landscapes was linked to landscape physiography and permafrost attributes, while between-landscape variability largely corresponded to differences in surficial geology. We conclude that continued increases in tundra productivity in the region are likely in upland tundra landscapes with fine-textured, cryoturbated soils; these areas currently tend to support discontinuous vegetation cover, but are highly susceptible to rapid increases in vegetation cover, as well as land-cover changes associated with the development of tall shrublands. (paper)

Journal of Biosciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

To estimate the N2 fixation ability of the alder (Alnus hirsuta (Turcz.) var. sibirica), we examined the seasonal variation in nitrogenase activity of nodules using the acetylene reduction method in an 18-year-old stand naturally regenerated after disturbance by road construction in Japan. To evaluate the contribution of N2 ...

Understory plant diversity in riparian alder-conifer stands after logging in southeast Alaska.

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Robert L. Deal

1997-01-01

Stand structure, tree height growth, and understory plant diversity were assessed in five mixed alder-conifer stands after logging in southeast Alaska. Tree species composition ranged from 7- to 91-percent alder, and basal area ranged from 30 to 55 m2/ha. The alder exhibited rapid early height growth, but recent growth has slowed considerably. Some conifers have...

Changes in Species Composition in Alder Swamp Forest Following Forest Dieback

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Remigiusz Pielech

2018-06-01

Full Text Available It is generally hypothesized that forest dieback is a characteristic of alder swamp forests (alder carrs, Alnion glutinosae alliance. Different internal and external factors may trigger this process, including human disturbance, changes in river discharge, unusually severe and prolonged flooding, terminal age of an even-aged alder forest (ca. 100–150 years and others. Although forest dieback in this type of forest may cause major changes in environmental conditions, the influence of this change on the floristic composition has not been well recognized. The study aimed to detect any possible changes in floristic variation in alder swamp forest following forest dieback. Vegetation plots in alder swamp forests affected by forest dieback were resurveyed 20 years after a previous study. PERMANOVA was used to test the significance of the compositional change and nonmetric multidimensional scaling (NMDS with passively fitted means of the Ellenberg’s Indicator Values were used to interpret its ecological meaning. In addition, different structural and diversity indices were compared, including species richness, percentage cover of vegetation layers, Shannon and Simpson diversity and evenness. Finally, we analyzed changes in the frequency of vascular plant species using Chi square tests. We recorded clear and significant compositional changes following alder swamp forest dieback. This change was most related to the gradient of moisture, followed by the gradients of light and temperature. The analysis of the individual species showed that the species of hummocks declined, while the species of hollows increased. Moreover, the current communities are dominated by some hydrophytes that were not recorded 20 years ago. Forest dieback resulted in profound changes in the hydrological regime. The observed changes are consistent with a model of cyclic succession as proposed for alder swamps. In addition, we conclude that the natural forest dynamics have to be

Heavy metal stress in alders: Tolerance and vulnerability of the actinorhizal symbiosis.

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Bélanger, Pier-Anne; Bellenger, Jean-Philippe; Roy, Sébastien

2015-11-01

Alders have already demonstrated their potential for the revegetation of both mining and industrial sites. These actinorhizal trees and shrubs and the actinobacteria Frankia associate in a nitrogen-fixing symbiosis which could however be negatively affected by the presence of heavy metals, and accumulate them. In our hydroponic assay with black alders, quantification of the roots and shoots metal concentrations showed that, in the absence of stress, symbiosis increases Mo and Ni root content and simultaneously decreases Mo shoot content. Interestingly, the Mo shoot content also decreases in the presence of Ni, Cu, Pb, Zn and Cd for symbiotic alders. In symbiotic alders, Pb shoot translocation was promoted in presence of Pb. On the other hand, Cd exclusion in symbiotic root tissues was observed with Pb and Cd. In the presence of symbiosis, only Cd and Pb showed translocation into aerial tissues when present in the nutrient solution. Moreover, the translocation of Ni to shoot was prevented by symbiosis in the presence of Cd, Ni and Pb. The hydroponic experiment demonstrated that alders benefit from the symbiosis, producing more biomass (total, root and shoot) than non nodulated alders in control condition, and in the presence of metals (Cu, Ni, Zn, Pb and Cd). Heavy metals did not reduce the nodule numbers (SNN), but the presence of Zn or Cd did reduce nodule allocation. Our study suggests that the Frankia-alder symbiosis is a promising (and a compatible) plant-microorganism association for the revegetation of contaminated sites, with minimal risk of metal dispersion. Copyright © 2015 Elsevier Ltd. All rights reserved.

Intramolecular Diels-Alder reactions of pyrimidines, a synthetic and computational study

NARCIS (Netherlands)

Stolle, W.A.W.

1992-01-01

This thesis deals with an investigation on the ringtransformation reactions of 2and 5-(ω-alkynyl)pyrimidine derivatives, which undergo upon heating an intramolecular Diels-Alder reaction and subsequently a spontaneous retro Diels- Alder reaction. To get a better insight into the

The hexadehydro-Diels-Alder reaction.

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Hoye, Thomas R; Baire, Beeraiah; Niu, Dawen; Willoughby, Patrick H; Woods, Brian P

2012-10-11

Arynes (aromatic systems containing, formally, a carbon-carbon triple bond) are among the most versatile of all reactive intermediates in organic chemistry. They can be 'trapped' to give products that are used as pharmaceuticals, agrochemicals, dyes, polymers and other fine chemicals. Here we explore a strategy that unites the de novo generation of benzynes-through a hexadehydro-Diels-Alder reaction-with their in situ elaboration into structurally complex benzenoid products. In the hexadehydro-Diels-Alder reaction, a 1,3-diyne is engaged in a [4+2] cycloisomerization with a 'diynophile' to produce the highly reactive benzyne intermediate. The reaction conditions for this simple, thermal transformation are notable for being free of metals and reagents. The subsequent and highly efficient trapping reactions increase the power of the overall process. Finally, we provide examples of how this de novo benzyne generation approach allows new modes of intrinsic reactivity to be revealed.

Diels-Alder reactions of inert aromatic compounds within a self-assembled coordination cage.

Science.gov (United States)

Horiuchi, Shinnosuke; Murase, Takashi; Fujita, Makoto

2011-07-04

A self-assembled coordination cage serves as a nanometer-sized molecular flask to promote the Diels-Alder reactions of aromatic hydrocarbons with N-cyclohexylmaleimide. The coordination cage accelerated the Diels-Alder reaction of anthracene at the electronically unfavorable, terminal benzene ring to give a compact, cavity-restrained syn-adduct. Activation-parameter measurements for the reactions revealed considerable reduction in the entropy cost, and preorganization of the substrates is a dominant factor in the enhanced reactivity. Owing to this entropy-cost reduction, otherwise-unreactive aromatic compounds, such as naphthalenes or triphenylene, also underwent Diels-Alder reactions in a regio- and stereocontrolled fashion. In the naphthalene Diels-Alder reaction, X-ray crystallographic analysis of the guest-inclusion complex clarified the reinforced orientation and proximity of the substrate pairs before the reaction. A perylene Diels-Alder adduct was stabilized inside the cage and protected from aerial oxidation. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Asymmetric Diels-Alder reactions with 5-menthyloxy-2(5H)-furanones

NARCIS (Netherlands)

Jong, Johannes Cornelis de

2006-01-01

At the beginning of the reseach described in this thesis the catalytic asymmetric Diels-Alder reaction had scarcely been investigated. No good catalytic processes with high enantiomeric excess were known at that time. At the same time the Diels-Alder reactions with chiral dienophiles needed further

Germination of red alder seed.

Science.gov (United States)

M.A. Radwan; D.S. DeBell

1981-01-01

Red alder seeds were collected from six locations throughout the natural range of the species. Each seed lot was obtained from a single tree, and the seeds were used to determine germination with and without stratification treatment. Irrespective of treatment, germination varied significantly (P

Impact of wind-induced microsites and disturbance severity on tree regeneration patterns: Results from the first post-storm decade

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Floor Vodde; Kalev Jogiste; Jeroen Engelhart; Lee E. Frelich; W. Keith Moser; Alan Sims; Marek Metslaid

2015-01-01

In two hemiboreal mixed spruce-hardwood forests in north-east Estonia, we studied (1) which factors affect tree regeneration survival and development during the first post-storm decade and (2) how these effects change in time. Regeneration height and mortality of the tree species black alder (Alnus glutinosa (L.) J. Gaertn.), birch (Betula pendula Roth., Betula...

Effects of riparian canopy opening and salmon carcass addition on the abundance and growth of resident salmonids

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Margaret A. Wilzbach; Bret C. Harvey; Jason L. White; Rodney J. Nakamoto

2005-01-01

We studied the concurrent effects of riparian canopy opening and salmon carcass addition on salmonid biomass, density and growth rates in small streams over 2 years. In each of six streams in the Smith and Klamath River basins in northern California, red alder (Alnus rubra) and other hardwoods were removed along both banks of a 100-m reach to...

Carbon and nitrogen metabolism of free-living Frankia spp. and of Frankia-alnus symbioses

NARCIS (Netherlands)

Blom, J.

1982-01-01

The research reported in this thesis deals with the symbiosis of Frankia spp. and Alnus glutinosa. Frankia spp. are actinomycetes giving rise to the formation of nitrogen-fixing nodules on the roots of a number of non-leguminous plants. In these nodules

Diels-Alder reactions: The effects of catalyst on the addition reaction

Science.gov (United States)

Yilmaz, Özgür; Kus, Nermin Simsek; Tunç, Tuncay; Sahin, Ertan

2015-10-01

The reaction between 2,3-dimethyl-1,3-butadiene and dimethyl 7-oxabicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylate is efficiently achieved with small amounts of catalyst, i.e. phenol, AcOH, nafion, and β-cyclodextrin. Exo-diastereoselective cycloaddition reactions were observed both without catalyst and different catalysts for 48 days. As a result, different products (tricyclicmolecule 5, retro-Diels-Alder product 6, and oxidation product 7) were obtained with different catalysts. In addition, we synthesized Diels-Alders product 8 and tricyclocyclitol 10 via Diels-Alder reaction. The structures of these products were characterized by 1H NMR, 13C NMR, MS and IR spectroscopy.

Bioinspired intramolecular Diels-Alder reaction: a rapid access to the highly-strained cyclopropane-fused polycyclic skeleton.

Science.gov (United States)

Zhu, Shifa; Guo, Zhengjiang; Huang, Zhipeng; Jiang, Huanfeng

2014-02-24

A bioinsipred gold-catalyzed tandem Diels-Alder/Diels-Alder reaction of an enynal and a 1,3-diene, forming the highly-strained benzotricyclo[3.2.1.0(2,7) ]octane skeleton, was reported. In contrast, a Diels-Alder/Friedel-Crafts tandem reaction occurred instead when silver salts were used as the catalyst. Although both reactions experienced the similar Diels-Alder reaction of a pyrylium intermediate with a 1,3-diene, they have different reaction mechanisms. The former proceeded with a stepwise Diels-Alder reaction, while the latter one with a concerted one. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Diels–Alder cycloaddition of 2-methylfuran and ethylene for renewable toluene

Energy Technology Data Exchange (ETDEWEB)

Green, Sara K.; Patet, Ryan E.; Nikbin, Nima; Williams, C. Luke; Chang, Chun-Chih; Yu, Jingye; Gorte, Raymond J.; Caratzoulas, Stavros; Fan, Wei; Vlachos, Dionisios G.; Dauenhauer, Paul J.

2016-01-01

Diels–Alder cycloaddition of biomass-derived 2-methylfuran and ethylene provides a thermochemical pathway to renewable toluene. In this work, the kinetics and reaction pathways of toluene formation have been evaluated with H-BEA and Sn-BEA catalysts. Kinetic analysis of the main reaction chemistries reveals the existence of two rate-controlling reactions: (i) Diels–Alder cycloaddition of 2-methylfuran and ethylene where the production rate is independent of the Brønsted acid site concentration, and (ii) dehydration of the Diels–Alder cycloadduct where the production rate is dependent on the Brønsted acid site concentration. Application of a reduced kinetic model supports the interplay of these two regimes with the highest concentration of toluene measured at a catalyst loading equal to the transition region between the two kinetic regimes. Selectivity to toluene never exceeded 46%, as 2-methylfuran was consumed by several newly identified reactions to side products, including dimerization of 2-methylfuran, the formation of a trimer following hydrolysis and ring-opening of 2-methylfuran, and the incomplete dehydration of the Diels–Alder cycloadduct of 2-methylfuran and ethylene.

Modeling climate impact on an emerging disease, the Phytophthora alni-induced alder decline.

Science.gov (United States)

Aguayo, Jaime; Elegbede, Fabrice; Husson, Claude; Saintonge, François-Xavier; Marçais, Benoît

2014-10-01

Alder decline caused by Phytophthora alni is one of the most important emerging diseases in natural ecosystems in Europe, where it has threatened riparian ecosystems for the past 20 years. Environmental factors, such as mean site temperature and soil characteristics, play an important role in the occurrence of the disease. The objective of the present work was to model and forecast the effect of environment on the severity of alder Phytophthora outbreaks, and to determine whether recent climate change might explain the disease emergence. Two alder sites networks in NE and SW France were surveyed to assess the crown health of trees; the oomycete soil inoculum was also monitored in the NE network. The main factors explaining the temporal annual variation in alder crown decline or crown recovery were the mean previous winter and previous summer temperatures. Both low winter temperatures and high summer temperatures were unfavorable to the disease. Cold winters promoted tree recovery because of poor survival of the pathogen, while hot summer temperature limited the incidence of tree decline. An SIS model explaining the dynamics of the P. alni-induced alder decline was developed using the data of the NE site network and validated using the SW site network. This model was then used to simulate the frequency of declining alder over time with historical climate data. The last 40 years' weather conditions have been generally favorable to the establishment of the disease, indicating that others factors may be implicated in its emergence. The model, however, showed that the climate of SW France was much more favorable for the disease than that of the Northeast, because it seldom limited the overwintering of the pathogen. Depending on the European area, climate change could either enhance or decrease the severity of the alder decline. © 2014 John Wiley & Sons Ltd.

The asymmetric hetero-Diels-Alder reaction in the syntheses of biologically relevant compounds.

Science.gov (United States)

Eschenbrenner-Lux, Vincent; Kumar, Kamal; Waldmann, Herbert

2014-10-13

The hetero-Diels-Alder reaction is one of the most powerful transformations in the chemistry toolbox for the synthesis of aza- and oxa-heterocycles embodying multiple stereogenic centers. However, as compared to other cycloadditions, in particular the dipolar cycloadditions and the Diels-Alder reaction, the hetero-Diels-Alder reaction has been much less explored and exploited in organic synthesis. Nevertheless, this powerful transformation has opened up efficient and creative routes to biologically relevant small molecules and different natural products which contain six-membered oxygen or nitrogen ring systems. Recent developments in this field, in particular in the establishment of enantioselectively catalyzed hetero-Diels-Alder cycloadditions steered by a plethora of different catalysts and the application of the resulting small molecules in chemical biology and medicinal chemistry research, are highlighted in this Minireview. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Growth and Survival of Hardwoods and Pine Interplanted with European Alder

Science.gov (United States)

William T. Plass

1977-01-01

European black alder is recommended for planting on many surface mine spoils in the eastern United States. It grows rapidly on a range of spoil types and contributes to soil enrichment by fixing nitrogen and providing a leaf fall rich in nutrients. This study evaluated the effect of alder on the survival and growth of five hardwood and five pine species. After 10...

Niobium Pentachloride Activation of Enone Derivatives: Diels-Alder and Conjugate Addition Products

Directory of Open Access Journals (Sweden)

Gil Valdo José da Silva

2002-05-01

Full Text Available Niobium pentachloride has proven to be a powerful activating agent for Diels-Alder or conjugate addition reactions of cycloenones. The Diels-Alder product was obtained only with an unsubstituted enone (cyclohexenone and the highly reactive diene cyclopentadiene; substituents in the b-position of enones seem to prevent Diels-Alder reaction: oxygenated substituents favor the formation of vinyl chlorides (ethyl ether or dichloromethane as solvents or enol ethers (ethyl acetate as solvent, while a methyl substituent prevents any kind of transformation with NbCl5. Less reactive dienes, furan and 2-methylfuran gave the conjugate addition products of the furan ring to the enone system.

Reaction energetics on long-range corrected density functional theory: Diels-Alder reactions.

Science.gov (United States)

Singh, Raman K; Tsuneda, Takao

2013-02-15

The possibility of quantitative reaction analysis on the orbital energies of long-range corrected density functional theory (LC-DFT) is presented. First, we calculated the Diels-Alder reaction enthalpies that have been poorly given by conventional functionals including B3LYP functional. As a result, it is found that the long-range correction drastically improves the reaction enthalpies. The barrier height energies were also computed for these reactions. Consequently, we found that dispersion correlation correction is also crucial to give accurate barrier height energies. It is, therefore, concluded that both long-range exchange interactions and dispersion correlations are essentially required in conventional functionals to investigate Diels-Alder reactions quantitatively. After confirming that LC-DFT accurately reproduces the orbital energies of the reactant and product molecules of the Diels-Alder reactions, the global hardness responses, the halves of highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy gaps, along the intrinsic reaction coordinates of two Diels-Alder reactions were computed. We noticed that LC-DFT results satisfy the maximum hardness rule for overall reaction paths while conventional functionals violate this rule on the reaction pathways. Furthermore, our results also show that the HOMO-LUMO gap variations are close to the reaction enthalpies for these Diels-Alder reactions. Based on these results, we foresee quantitative reaction analysis on the orbital energies. Copyright © 2012 Wiley Periodicals, Inc.

Diels-Alder reactions in confined spaces: the influence of catalyst structure and the nature of active sites for the retro-Diels-Alder reaction.

Science.gov (United States)

Cantín, Ángel; Gomez, M Victoria; de la Hoz, Antonio

2016-01-01

Diels-Alder cycloaddition between cyclopentadiene and p -benzoquinone has been studied in the confined space of a pure silica zeolite Beta and the impact on reaction rate due to the concentration effect within the pore and diffusion limitations are discussed. Introduction of Lewis or Brønsted acid sites on the walls of the zeolite strongly increases the reaction rate. However, contrary to what occurs with mesoporous molecular sieves (MCM-41), Beta zeolite does not catalyse the retro-Diels-Alder reaction, resulting in a highly selective catalyst for the cycloaddition reaction.

A Near-Infrared Photothermal Effect-Responsive Drug Delivery System Based on Indocyanine Green and Doxorubicin-Loaded Polymeric Micelles Mediated by Reversible Diels-Alder Reaction.

Science.gov (United States)

Li, Hui; Li, Junjie; Ke, Wendong; Ge, Zhishen

2015-10-01

Near-infrared light (NIR) possesses great advantages for light-responsive controllable drug release, such as deep tissue penetration and low damage to healthy tissues. Herein, a NIR-responsive drug delivery system is developed based on a NIR dye, indocyanine green (ICG), and anticancer drug, doxorubicin (DOX)-loaded thermoresponsive block copolymer micelles, in which the drug release can be controlled via NIR irradiation. First, block copolymers, poly(oligo(ethylene glycol) methacrylate)-block-poly(furfuryl methacrylate) (POEGMA-b-PFMA), are synthesized by sequential reversible addition-fragmentation chain-transfer (RAFT) polymerization, followed by modification with N-octyl maleimide through Diels-Alder (DA) reaction to produce POEGMA-b-POMFMA. The self-assembly of POEGMA-b-POMFMA by nano-precipitation in aqueous solution affords the polymeric micelles which are used to simultaneously encapsulate ICG and DOX. Upon irradiation by NIR light (805 nm), the loaded DOX is released rapidly from the micelles due to partial retro DA reaction and local temperature increase-induced faster drug diffusion by the photothermal effect. Cytotoxicity evaluation and intracellular distribution observation demonstrate significant synergistic effects of NIR-triggered drug release, photothermal, and chemotherapy toward cancer cells under NIR irradiation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pyrrole PMOs, incorporating new N-heterocyclic compounds on an ethene-PMO through Diels–Alder reactions

International Nuclear Information System (INIS)

Esquivel, Dolores; De Canck, Els; Jiménez-Sanchidrián, César; Romero-Salguero, Francisco J.; Van Der Voort, Pascal

2014-01-01

The ethenylene bridges on the walls of an ethenylene-bridged periodic mesoporous organosilica were successfully modified with a variety of pyrrole derivatives – pyrrole, methylpyrrole, dimethylpyrrole, trimethylpyrrole and 1-phenylpyrrole – through Diels–Alder reactions. X-ray diffraction measurements and N 2 adsorption–desorption analysis confirmed the preservation of the ordering and mesoporosity of the parent material as well as the decoration of the pores with the surface Diels–Alder adducts. Moreover, other techniques such as DRIFT, 13 C and 29 Si nuclear magnetic resonances revealed the formation of the surface N-heterocyclic compounds at the parent ethenylene sites. - Highlights: • Chemical modification of the double bonds on an ethene-PMO through the Diels–Alder reaction. • A family of pyrrole derivatives act as dienes in the Diels–Alder reaction. • Well-ordering and mesoporosity are retained after the post-functionalization. • N-containing compounds on the surface of ethene-PMO are present after the Diels–Alder reaction

Pyrrole PMOs, incorporating new N-heterocyclic compounds on an ethene-PMO through Diels–Alder reactions

Energy Technology Data Exchange (ETDEWEB)

Esquivel, Dolores; De Canck, Els [Center for Ordered Materials, Organometallics and Catalysis, Department of Inorganic and Physical Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Ghent (Belgium); Jiménez-Sanchidrián, César [Department of Organic Chemistry, Nanochemistry and Fine Chemistry Research Institute (IUIQFN), Faculty of Sciences, University of Córdoba, Campus de Rabanales, Marie Curie Building, Ctra. Nnal. IV, km 396, 14071 Córdoba (Spain); Romero-Salguero, Francisco J., E-mail: qo2rosaf@uco.es [Department of Organic Chemistry, Nanochemistry and Fine Chemistry Research Institute (IUIQFN), Faculty of Sciences, University of Córdoba, Campus de Rabanales, Marie Curie Building, Ctra. Nnal. IV, km 396, 14071 Córdoba (Spain); Van Der Voort, Pascal, E-mail: pascal.vandervoort@ugent.be [Center for Ordered Materials, Organometallics and Catalysis, Department of Inorganic and Physical Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Ghent (Belgium)

2014-11-14

The ethenylene bridges on the walls of an ethenylene-bridged periodic mesoporous organosilica were successfully modified with a variety of pyrrole derivatives – pyrrole, methylpyrrole, dimethylpyrrole, trimethylpyrrole and 1-phenylpyrrole – through Diels–Alder reactions. X-ray diffraction measurements and N{sub 2} adsorption–desorption analysis confirmed the preservation of the ordering and mesoporosity of the parent material as well as the decoration of the pores with the surface Diels–Alder adducts. Moreover, other techniques such as DRIFT, {sup 13}C and {sup 29}Si nuclear magnetic resonances revealed the formation of the surface N-heterocyclic compounds at the parent ethenylene sites. - Highlights: • Chemical modification of the double bonds on an ethene-PMO through the Diels–Alder reaction. • A family of pyrrole derivatives act as dienes in the Diels–Alder reaction. • Well-ordering and mesoporosity are retained after the post-functionalization. • N-containing compounds on the surface of ethene-PMO are present after the Diels–Alder reaction.

Changes in sediment volume in Alder Lake, Nisqually River Basin, Washington, 1945-2011

Science.gov (United States)

Czuba, Jonathan A.; Olsen, Theresa D.; Czuba, Christiana R.; Magirl, Christopher S.; Gish, Casey C.

2012-01-01

The Nisqually River drains the southwest slopes of Mount Rainier, a glaciated stratovolcano in the Cascade Range of western Washington. The Nisqually River was impounded behind Alder Dam when the dam was completed in 1945 and formed Alder Lake. This report quantifies the volume of sediment deposited by the Nisqually and Little Nisqually Rivers in their respective deltas in Alder Lake since 1945. Four digital elevation surfaces were generated from historical contour maps from 1945, 1956, and 1985, and a bathymetric survey from 2011. These surfaces were used to compute changes in sediment volume since 1945. Estimates of the volume of sediment deposited in Alder Lake between 1945 and 2011 were focused in three areas: (1) the Nisqually River delta, (2) the main body of Alder Lake, along a 40-meter wide corridor of the pre-dam Nisqually River, and (3) the Little Nisqually River delta. In each of these areas the net deposition over the 66-year period was 42,000,000 ± 4,000,000 cubic meters (m3), 2,000,000 ± 600,000 m3, and 310,000 ± 110,000 m3, respectively. These volumes correspond to annual rates of accumulation of 630,000 ± 60,000 m3/yr, 33,000 ± 9,000 m3/yr, and 4,700 ± 1,600 m3/yr, respectively. The annual sediment yield of the Nisqually (1,100 ± 100 cubic meters per year per square kilometer [(m3/yr)/km2]) and Little Nisqually River basins [70 ± 24 (m3/yr)/km2] provides insight into the yield of two basins with different land cover and geomorphic processes. These estimates suggest that a basin draining a glaciated stratovolcano yields approximately 15 times more sediment than a basin draining forested uplands in the Cascade Range. Given the cumulative net change in sediment volume in the Nisqually River delta in Alder Lake, the total capacity of Alder Lake since 1945 decreased about 3 percent by 1956, 8 percent by 1985, and 15 percent by 2011.

DIELS-ALDER REACTIONS IN AQUEOUS-SOLUTIONS - ENFORCED HYDROPHOBIC INTERACTIONS BETWEEN DIENE AND DIENOPHILE

NARCIS (Netherlands)

BLOKZIJL, W; BLANDAMER, MJ; ENGBERTS, JBFN

1991-01-01

Second-order rate constants and isobaric activation parameters for the intermolecular Diels-Alder reactions of cyclopentadiene with alkyl vinyl ketones (2a,b) and 5-substituted-1,4-naphthoquinones (3a-c) as well as for the intramolecular Diels-Alder reaction of N-furfuryl-N-methylmaleamic acid (4)

The first organocatalytic, ortho-regioselective inverse-electron-demand hetero-Diels-Alder reaction.

Science.gov (United States)

Hejmanowska, Joanna; Jasiński, Marcin; Wojciechowski, Jakub; Mlostoń, Grzegorz; Albrecht, Łukasz

2017-10-17

The development of the unprecedented ortho-regioselective inverse-electron-demand hetero-Diels-Alder (IEDHDA) reaction is described. It has been demonstrated that by proper choice of reactants and reaction conditions the inverse-electron-demand hetero-Diels-Alder cycloaddition can be realized with unprecedented regioselectivity arising from the reaction between the terminal carbon atom of the dienophile and the heteroatom of the heterodiene.

Theoretical study of the Diels-Alder reaction between o-benzoquinone and norbornadiene

Science.gov (United States)

Quijano-Quiñones, Ramiro F.; Quesadas-Rojas, M.; Cuevas, Gabriel; Mena-Rejón, Gonzalo J.

2013-06-01

The reaction between norbornadiene and o-benzoquinone is an important step in polyalicyclic rigid structures synthesis. It has been considered that this reaction is an example of Diels-Alder (DA) and hetero-Diels-Alder (HDA) cycloadditions with o-benzoquinone acting as diene (forming C-C bonds) and heterodiene (forming O-C bonds). We have performed a Density Functional Theory study of this reaction, employing B3LYP, mPW1PW91, and B1B95 functionals and 6-31G(d,p) and 6-31+G(d,p) Gaussian type basis sets. The results indicate that Diels-Alder is a feasible mechanism for both reactions, but should not be the main route to the formation of products with C-C bonds.

Theoretical study of the Diels-Alder reaction between o-benzoquinone and norbornadiene

International Nuclear Information System (INIS)

Quijano-Quiñones, Ramiro F; Quesadas-Rojas, M; Mena-Rejón, Gonzalo J; Cuevas, Gabriel

2013-01-01

The reaction between norbornadiene and o-benzoquinone is an important step in polyalicyclic rigid structures synthesis. It has been considered that this reaction is an example of Diels-Alder (DA) and hetero-Diels-Alder (HDA) cycloadditions with o-benzoquinone acting as diene (forming C-C bonds) and heterodiene (forming O-C bonds). We have performed a Density Functional Theory study of this reaction, employing B3LYP, mPW1PW91, and B1B95 functionals and 6-31G(d,p) and 6-31+G(d,p) Gaussian type basis sets. The results indicate that Diels-Alder is a feasible mechanism for both reactions, but should not be the main route to the formation of products with C-C bonds.

N2-fixing red alder indirectly accelerates ecosystem nitrogen cycling

Science.gov (United States)

Perakis, Steven S.; Matkins, Joselin J.; Hibbs, David E.

2012-01-01

Symbiotic N2-fixing tree species can accelerate ecosystem N dynamics through decomposition via direct pathways by producing readily decomposed leaf litter and increasing N supply to decomposers, as well as via indirect pathways by increasing tissue and detrital N in non-fixing vegetation. To evaluate the relative importance of these pathways, we compared three-year decomposition and N dynamics of N2-fixing red alder leaf litter (2.34 %N) to both low-N (0.68 %N) and high-N (1.21 %N) litter of non-fixing Douglas-fir, and decomposed each litter source in four forests dominated by either red alder or Douglas-fir. We also used experimental N fertilization of decomposition plots to assess elevated N availability as a potential mechanism of N2-fixer effects on litter mass loss and N dynamics. Direct effects of N2-fixing red alder on decomposition occurred primarily as faster N release from red alder than Douglas-fir litter, but direct increases in N supply to decomposers via fertilization did not stimulate decomposition of any litter. Fixed N indirectly influenced detrital dynamics by increasing Douglas-fir tissue and litter N concentrations, which accelerated litter N release without accelerating mass loss. By increasing soil N, tissue N, and the rate of N release from litter of non-fixers, we conclude that N2-fixing vegetation can indirectly foster plant-soil feedbacks that contribute to the persistence of elevated N availability in terrestrial ecosystems.

Is it true that polymerization of vegetable oil occurs through Diels-Alder reaction?

Science.gov (United States)

Diels-Alder reaction mechanism is known to be one of the major reaction mechanisms to produce dimers and polymers during heating process of vegetable oil. However, our NMR study showed no evidence for Diels-Alder products. Soybean oil oxidized at 180 °C for 24 hrs with 1.45 surface area-to-volume ...

The Diels-Alder cyclization of ketenimines.

Science.gov (United States)

Erb, Jeremy; Strull, Jessica; Miller, David; He, Jean; Lectka, Thomas

2012-04-20

A Diels-Alder reaction between cyclopentadiene and a variety of ketenimines is reported. A copper(I)-bis(phosphine complex catalyzes the cycloaddition across the C═N bond of the ketenimine in a [4 + 2] reaction to give an enamine intermediate that is hydrolyzed upon purification to generate aminoketones. © 2012 American Chemical Society

Physical Characterisation and Quantification of Total Above Ground Biomass Derived from First Thinnings for Wood Fuel Consumption in Ireland

OpenAIRE

Mockler, Nicholas

2013-01-01

Comprehensive knowledge of wood fuel properties assists in the optimisation of operations concerned with the harvesting, seasoning, processing and conversion of wood to energy. This study investigated the physical properties of wood fuel. These properties included moisture content and basic density. The field work also allowed for the quantification of above ground biomass partitions. The species investigated were alder (Alnus glutinosa), ash (Fraxinus excelsior L.), birch (Betula spp.), lodg...

The Diels-Alder reaction: A powerful tool for the design of drug delivery systems and biomaterials.

Science.gov (United States)

Gregoritza, Manuel; Brandl, Ferdinand P

2015-11-01

Click reactions have the potential to greatly facilitate the development of drug delivery systems and biomaterials. These reactions proceed under mild conditions, give high yields, and form only inoffensive by-products. The Diels-Alder cycloaddition is one of the click reactions that do not require any metal catalyst; it is one of the most useful reactions in synthetic organic chemistry and material design. Herein, we highlight possible applications of the Diels-Alder reaction in pharmaceutics and biomedical engineering. Particular focus is placed on the synthesis of polymers and dendrimers for drug delivery, the preparation of functionalized surfaces, bioconjugation techniques, and applications of the Diels-Alder reaction in nanotechnology. Moreover, applications of the reaction for the preparation of hydrogels for drug delivery and tissue engineering are reviewed. A general introduction to the Diels-Alder reaction is presented, along with a discussion of potential pitfalls and challenges. At the end of the article, we provide a set of tools that may facilitate the application of the Diels-Alder reaction to solve important pharmaceutical or biomedical problems. Copyright © 2015 Elsevier B.V. All rights reserved.

Nitrogenase and nitrate reductase activities in young Alnus glutinosa, relationship and effect of light-dark treatments

International Nuclear Information System (INIS)

Benamar, S.; Thiery, G.; Pizelle, G.

1995-01-01

Relations between in vivo nitrogenase (N-2-ase; EC 1.18.6.1) and nitrate reductase (NR; EC 1.6.6.1) activities were studied in young nodulated Alnus glutinosa (L. ) Gaertn. Positive correlations linked N-2-ase activity, constitutive (non-inducible by nitrate) leaf NR activity and plant growth. Light/dark treatments applied to the whole shoot or, separately, to the upper and lower part of shoot led to the finding that(a) the constitutive leaf NR activity depended on direct illumination of the leaf and did not appear subordinate to the N-2-ase activity; (b) the N-2-ase activity was much more efficiently supported by the illumination of the upper (young) leaves than by that of the lower (mature) leaves; (c) the maintenance of nitrate-inducible root NR activity required leaf illumination. The variations of both N-2-ase and root NR activities in response to light/dark treatments emphasize the importance of the photosynthesis for the reduction of dinitrogen and nitrate in nodulated roots of Alnus glutinosa

Reaction of Aldehydes/Ketones with Electron-Deficient 1,3,5-Triazines Leading to Functionalized Pyrimidines as Diels-Alder/Retro-Diels-Alder Reaction Products: Reaction Development and Mechanistic Studies.

Science.gov (United States)

Yang, Kai; Dang, Qun; Cai, Pei-Jun; Gao, Yang; Yu, Zhi-Xiang; Bai, Xu

2017-03-03

Catalytic inverse electron demand Diels-Alder (IEDDA) reactions of heterocyclic aza-dienes are rarely reported since highly reactive and electron-rich dienophiles are often found not compatible with strong acids such as Lewis acids. Herein, we disclose that TFA-catalyzed reactions of electron-deficient 1,3,5-triazines and electron-deficient aldehydes/ketones can take place. These reactions led to highly functionalized pyrimidines as products in fair to good yields. The reaction mechanism was carefully studied by the combination of experimental and computational studies. The reactions involve a cascade of stepwise inverse electron demand hetero-Diels-Alder (ihDA) reactions, followed by retro-Diels-Alder (rDA) reactions and elimination of water. An acid was required for both ihDA and rDA reactions. This mechanism was further verified by comparing the relative reactivity of aldehydes/ketones and their corresponding vinyl ethers in the current reaction system.

Cross-amplification and multiplexing of SSR markers for Alnus glutinosa and A. incana

Czech Academy of Sciences Publication Activity Database

Drašnarová, Alena; Krak, Karol; Vít, Petr; Doudová, Jana; Douda, Jan; Hadincová, Věroslava; Zákravský, Petr; Mandák, Bohumil

2014-01-01

Roč. 10, č. 4 (2014), s. 865-873 ISSN 1614-2942 R&D Projects: GA ČR(CZ) GAP504/11/0402 Institutional support: RVO:67985939 Keywords : alder * Betulaceae * microcatelites Subject RIV: EF - Botanics Impact factor: 2.451, year: 2014

Nitrogen fixation and growth response of Alnus rubra amended with low and high metal content biosolids Crescimento e fixação de nitrogênio por Alnus rubra cultivado sob fertilização com biosólidos com altos e baixos teores de metais

Directory of Open Access Journals (Sweden)

Linda S. Gaulke

2006-08-01

Full Text Available Forest application of biosolids offers a potential environmentally friendly alternative to landfilling. This two-year investigation was designed to analyze the effects of elevated soil metal concentration resulting from the land application of biosolids on the symbiotic, nitrogen (N fixing relationship between Alnus rubra Bong. (red alder and Frankia. High metal biosolids and a modern-day composted biosolid applied at high loading rates of 250, 500, and 1000 Mg ha-1, were used to represent a worst-case scenario for metal contamination. The high metal biosolids were obtained before the current regulations were formulated and had been lagooned prior to use in this study. Total cadmium (Cd, lead (Pb and zinc (Zn in the high metal biosolids were 45, 958, and 2623 mg kg-1 respectively. These metal concentrations are above current regulatory limits in the US. The compost was made using biosolids that are currently produced and had Cd, Pb and Zn of 0.8, 20 and 160 mg kg-1 respectively. Trees were harvested and analyzed for rate of N fixation (as measured by acetylene reduction activity, biomass, and foliar metals. Soils were analyzed for available N, total carbon and N, pH and total Cd, Pb and Zn. Rates of N fixation were not affected by soil amendment. In year 2, shoot biomass of trees grown in both the compost and high metal amendments were higher than the control. Shoot biomass increased with increasing amount of compost amendments, but decreased with increasing amount of high metal amendments. There was no relationship between soil metal concentration and plant biomass. Foliar Cd and Pb were below detection for all trees and foliar Zn increased with increasing amount of both compost and high metal amendment, with concentrations of 249 mg kg-1 for trees grown in the compost amendment and 279 mg kg-1 for the high metal amendment. The results from this study indicate that the growth of A. rubra benefited from both types of biosolids used in the study

Biology and ecology of red alder.

Science.gov (United States)

Constance A. Harrington

2006-01-01

Red alder is the most common hardwood in the Pacific Northwest with a range stretching from coastal southeast Alaska to southern California and east to isolated populations in Idaho. Soil moisture during the growing season influences where it grows and its growth rates; it can tolerate poor drainage but not droughty, hot sites. Due to its tolerance of wet soil...

Diels–Alder reactions of myrcene using intensified continuous-flow reactors

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Christian H. Hornung

2017-01-01

Full Text Available This work describes the Diels–Alder reaction of the naturally occurring substituted butadiene, myrcene, with a range of different naturally occurring and synthetic dienophiles. The synthesis of the Diels–Alder adduct from myrcene and acrylic acid, containing surfactant properties, was scaled-up in a plate-type continuous-flow reactor with a volume of 105 mL to a throughput of 2.79 kg of the final product per day. This continuous-flow approach provides a facile alternative scale-up route to conventional batch processing, and it helps to intensify the synthesis protocol by applying higher reaction temperatures and shorter reaction times.

Interspecific Plant Interactions Reflected in Soil Bacterial Community Structure and Nitrogen Cycling in Primary Succession.

Science.gov (United States)

Knelman, Joseph E; Graham, Emily B; Prevéy, Janet S; Robeson, Michael S; Kelly, Patrick; Hood, Eran; Schmidt, Steve K

2018-01-01

Past research demonstrating the importance plant-microbe interactions as drivers of ecosystem succession has focused on how plants condition soil microbial communities, impacting subsequent plant performance and plant community assembly. These studies, however, largely treat microbial communities as a black box. In this study, we sought to examine how emblematic shifts from early successional Alnus viridus ssp. sinuata (Sitka alder) to late successional Picea sitchensis (Sitka spruce) in primary succession may be reflected in specific belowground changes in bacterial community structure and nitrogen cycling related to the interaction of these two plants. We examined early successional alder-conditioned soils in a glacial forefield to delineate how alders alter the soil microbial community with increasing dominance. Further, we assessed the impact of late-successional spruce plants on these early successional alder-conditioned microbiomes and related nitrogen cycling through a leachate addition microcosm experiment. We show how increasingly abundant alder select for particular bacterial taxa. Additionally, we found that spruce leachate significantly alters the composition of these microbial communities in large part by driving declines in taxa that are enriched by alder, including bacterial symbionts. We found these effects to be spruce specific, beyond a general leachate effect. Our work also demonstrates a unique influence of spruce on ammonium availability. Such insights bolster theory relating the importance of plant-microbe interactions with late-successional plants and interspecific plant interactions more generally.

Seasonal variation in radiocesium concentrations in three tree species

International Nuclear Information System (INIS)

Garten, C.R. Jr.; Briese, L.A.; Sharitz, R.R.; Gentry, J.B.

1975-01-01

Radiocesium concentrations in leaves and stems of black willow (Salix nigra), wax myrtle (Myrica cerifera), and tag alder (Alnus serrulata) trees inhabiting a floodplain contaminated by production-reactor effluents were measured over 1 year. In willow and myrtle trees, leaf radiocesium levels were highest in the spring and declined during the growing season; stem levels remained relatively unchanged or exhibited a slight increase. Seasonal changes in alder tree parts depended on the site examined. The relationship among component parts was essentially consistent across species and collecting sites in the summer. The radiocesium concentrations in order of rank were: roots greater than or equal to leaves greater than stems. Species differences in component-part radiocesium levels were dependent on the part sampled and the collecting site examined. Mean soil to plant-part concentration factors in summer ranged from 0.9 to 7.6, and species means across leaves, stems, and roots averaged 2.1, 3.8, and 6.2 for alder, willow, and myrtle trees, respectively

Covalently crosslinked diels-alder polymer networks.

Energy Technology Data Exchange (ETDEWEB)

Bowman, Christopher (University of Colorado, Boulder, CO); Adzima, Brian J. (University of Colorado, Boulder, CO); Anderson, Benjamin John

2011-09-01

This project examines the utility of cycloaddition reactions for the synthesis of polymer networks. Cycloaddition reactions are desirable because they produce no unwanted side reactions or small molecules, allowing for the formation of high molecular weight species and glassy crosslinked networks. Both the Diels-Alder reaction and the copper-catalyzed azide-alkyne cycloaddition (CuAAC) were studied. Accomplishments include externally triggered healing of a thermoreversible covalent network via self-limited hysteresis heating, the creation of Diels-Alder based photoresists, and the successful photochemical catalysis of CuAAC as an alternative to the use of ascorbic acid for the generation of Cu(I) in click reactions. An analysis of the results reveals that these new methods offer the promise of efficiently creating robust, high molecular weight species and delicate three dimensional structures that incorporate chemical functionality in the patterned material. This work was performed under a Strategic Partnerships LDRD during FY10 and FY11 as part of a Sandia National Laboratories/University of Colorado-Boulder Excellence in Science and Engineering Fellowship awarded to Brian J. Adzima, a graduate student at UC-Boulder. Benjamin J. Anderson (Org. 1833) was the Sandia National Laboratories point-of-contact for this fellowship.

Fe(II)/Fe(III)-Catalyzed Intramolecular Didehydro-Diels-Alder Reaction of Styrene-ynes.

Science.gov (United States)

Mun, Hyeon Jin; Seong, Eun Young; Ahn, Kwang-Hyun; Kang, Eun Joo

2018-02-02

The intramolecular didehydro-Diels-Alder reaction of styrene-ynes was catalyzed by Fe(II) and Fe(III) to produce various naphthalene derivatives under microwave heating conditions. Mechanistic calculations found that the Fe(II) catalyst activates the styrenyl diene in an inverse-electron-demand Diels-Alder reaction, and the consecutive dehydrogenation reaction can be promoted by either Fe(II)-catalyzed direct dehydrogenation or an Fe(III)-catalyzed rearomatization/dehydrogenation pathway.

Fourfold Diels-Alder reaction of tetraethynylsilane.

Science.gov (United States)

Geyer, Florian L; Rode, Alexander; Bunz, Uwe H F

2014-12-08

A series of ethynylated silanes, including tetraethynylsilane, was treated with tetraphenylcyclopentadienone at 300 °C under microwave irradiation to give the aromatized Diels-Alder adducts as sterically encumbered mini-dendrimers with up to 20 benzene rings. The sterically most congested adducts display red-shifted emission through intramolecular π-π interactions in the excited state. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Ligand Structure-Activity Study of DNA-Based Catalytic Asymmetric Hydration and Diels-Alder Reactions

NARCIS (Netherlands)

Rosati, F.; Roelfes, J.G.

A structure-activity relationship study of the first generation ligands for the DNA-based asymmetric hydration of enones and Diels-Alder reaction in water is reported. The design of the ligand was optimized resulting in a maximum ee of 83% in the hydration reaction and 75% in the Diels-Alder

Modified lignin: Preparation and use in reversible gel via Diels-Alder reaction.

Science.gov (United States)

Zhou, Wanpeng; Zhang, Hui; Chen, Fangeng

2018-02-01

In this study, popular soda lignin was modified with either furan or maleimide ring, and the modified lignins were subjected to reversible Diels-Alder reaction. A new process was proposed to prepare the functionalized lignin. A long chain was introduced to the hydroxyl groups of lignin, and then either the furan or maleimide ring was added to the other end of the chain. The test results confirmed that either the furan ring or the maleimide ring was bound to lignin. Furan- and maleimide-functionalized lignins were also combined to generate crosslinking via Diels-Alder [4+2] cycloaddition reaction. Under appropriate conditions, the formation of a gel was identified, which reverted to liquid state after retro Diels-Alder reaction upon heating at 120°C. This study reveals the significant versatility and potential of the developed strategy for the utilization of lignin-based recyclable networks. Copyright © 2017 Elsevier B.V. All rights reserved.

Informe preliminar sobre aspectos de la biología del Aliso (Alnus acuminata h.b.k.

Directory of Open Access Journals (Sweden)

Garcés de Granada Emira

1986-12-01

Full Text Available Las especies del género Alnus se consideran de gran Importancia porque la raíz se asocia simblóticamente con Actinomycetes, formando nódulos fijadores de nitrógeno atmosférico, siendo este el principal mecanismo para la Incorporación de nitrógeno reducido en suelos pobres (Burns y Hardy, 1975; Torrey, 1976; Normand y Lalonde, 1982. En colombia el Aliso (Alnus acumlnata H.B.K., se encuentra ampliamente distribuido y se ha Iniciado su utilizAción en proyectos de reforestación (Cáceres y Oyola, 1981. La madera es empleada como carbón vegetal y para la fabricación de cajas, cajones, palillos y postes (Slcco
et al., 1965, también es Importante por el contenido de tanino (Torres, 1983. Sin embargo se hace necesario conocer aspectos básicos de la biologla de esta especie que
incluyan germinación, fenologla, crecimiento, desarrollo y las interacciones entre la planta y otros organismos asociados, de los cuales se desconoce su relación biológica.

Proximate weather patterns and spring green-up phenology effect Eurasian beaver (Castor fiber) body mass and reproductive success: the implications of climate change and topography.

Science.gov (United States)

Campbell, Ruairidh D; Newman, Chris; Macdonald, David W; Rosell, Frank

2013-04-01

Low spring temperatures have been found to benefit mobile herbivores by reducing the rate of spring-flush, whereas high rainfall increases forage availability. Cold winters prove detrimental, by increasing herbivore thermoregulatory burdens. Here we examine the effects of temperature and rainfall variability on a temperate sedentary herbivore, the Eurasian beaver, Castor fiber, in terms of inter-annual variation in mean body weight and per territory offspring production. Data pertain to 198 individuals, over 11 years, using capture-mark-recapture. We use plant growth (tree cores) and fAPAR (a satellite-derived plant productivity index) to examine potential mechanisms through which weather conditions affect the availability and the seasonal phenology of beaver forage. Juvenile body weights were lighter after colder winters, whereas warmer spring temperatures were associated with lighter adult body weights, mediated by enhanced green-up phenology rates. Counter-intuitively, we observed a negative association between rainfall and body weight in juveniles and adults, and also with reproductive success. Alder, Alnus incana, (n = 68) growth rings (principal beaver food in the study area) exhibited a positive relationship with rainfall for trees growing at elevations >2 m above water level, but a negative relationship for trees growing beavers at the landscape scale via effects on spring green-up phenology and winter thermoregulation. Rainfall influences beavers at finer spatial scales through topographical interactions with plant growth, where trees near water level, prone to water logging, producing poorer forage in wetter years. Unlike most other herbivores, beavers are an obligate aquatic species that utilize a restricted 'central-place' foraging range, limiting their ability to take advantage of better forage growth further from water during wetter years. With respect to anthropogenic climate change, interactions between weather variables, plant phenology and

Investigation of the possibility of functionalization of C20 fullerene by benzene via Diels-Alder reaction

Science.gov (United States)

Siadati, Seyyed Amir; Nami, Navabeh

2016-10-01

C20 fullerene, this novel species with all its pentagonal faces has displayed some unique operations in making fast pericyclic reactions. As an example, the high dienophile character of the C20 fullerene and the ability of this species in making an ultra-fast Diels-Alder reaction with 1,3-butadiene, has been recently reported. Moreover, new experimental reports claim that the C60 fullerene, one of the fullerene family, could make a Diels-Alder reaction with the central ring of anthracene and make the ring non-aromatic. These reports may encourage researchers to do more studies on the properties of this small carbon cage. To address this question, the present research has discussed all the reaction channels of the Diels-Alder cycloaddition of benzene molecule as a 1,3-diene with the C20 fullerene in order to answer this question: ;Is C20fullerene able to make a Diels-Alder reaction with this molecule?;.

Berni Alder and Phase Transitions in Two Dimensions

Science.gov (United States)

Kosterlitz, J. Michael

I do not know Berni Alder as a person, but I feel that I know him well through his seminal paper "Phase Transition in Elastic Disks𠇍 by B. J. Alder and T. E. Wainwright [1962], which was essential in motivating David Thouless and myself to think about phase transitions in two dimensional systems with a continuous symmetry. In the early 1970's, the conventional wisdom was that a crystalline solid could not exist in a two dimensional world because of the rigorous Mermin-Wagner theorem prohibiting true long range translational order at any non-zero temperature. This contradiction was settled by the theory of dislocation mediated melting to an intermediate hexatic phase followed by a second transition to the isotropic fluid at a higher temperature. This scenario, with its associated sophisticated theory, seemed to settle the controversy of two dimensional melting once and for all. However, in our elation at understanding the fundamental physics and the essential excitations of melting in 2D, we had all forgotten that the early work of Berni Alder also showed that this melting involved a weak first order transition while theory now predicted melting by two successive continuous transitions with no discontinuity in area at the critical pressure. This discrepancy could be hand waved away by arguing that Berni's system was far too small and his computers far too slow so that the areal discontinuity could be due to finite size effects or to failing to equilibrate the system. Experiments were not able to resolve the order of the transitions, but seemed to agree quantitatively with theory…

A preliminary study of the deterioration of alder and Douglas-fir chips in outdoor piles.

Science.gov (United States)

Ernest. Wright

1954-01-01

In the fall of 1952, E. E. Matson of the Pacific Northwest Forest and Range Experiment Station learned that the Fir-Tex Insulating Board Company bf St. Helens, Oregon was considering mixing alder with Douglas-fir chips for outside storage. Since alder heartwood i s more susceptible to decay than that of Douglas-fir, the question arose whether mixing the two might...

Early survival and growth of planted Douglas-fir with red alder in four mixed regimes.

Science.gov (United States)

Marshall D. Murray; Richard E. Miller

1986-01-01

To quantify between-species interactions, we measured and compared survival and growth of planted Douglas-fir and associated planted and volunteer red alder at a location on the west side of the Cascade Range in Washington. The planted alder were wildlings dug either from a nearby area or from a distant, coastal site and interplanted into a 3-year-old Douglas-fir...

Quinones as dienophiles in the Diels-Alder reaction: history and applications in total synthesis.

Science.gov (United States)

Nawrat, Christopher C; Moody, Christopher J

2014-02-17

In the canon of reactions available to the organic chemist engaged in total synthesis, the Diels-Alder reaction is among the most powerful and well understood. Its ability to rapidly generate molecular complexity through the simultaneous formation of two carbon-carbon bonds is almost unrivalled, and this is reflected in the great number of reported applications of this reaction. Historically, the use of quinones as dienophiles is highly significant, being the very first example investigated by Diels and Alder. Herein, we review the application of the Diels-Alder reaction of quinones in the total synthesis of natural products. The highlighted examples span some 60 years from the landmark syntheses of morphine (1952) and reserpine (1956) by Gates and Woodward, respectively, through to the present day examples, such as the tetracyclines. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Interspecific Plant Interactions Reflected in Soil Bacterial Community Structure and Nitrogen Cycling in Primary Succession

Directory of Open Access Journals (Sweden)

Joseph E. Knelman

2018-02-01

Full Text Available Past research demonstrating the importance plant–microbe interactions as drivers of ecosystem succession has focused on how plants condition soil microbial communities, impacting subsequent plant performance and plant community assembly. These studies, however, largely treat microbial communities as a black box. In this study, we sought to examine how emblematic shifts from early successional Alnus viridus ssp. sinuata (Sitka alder to late successional Picea sitchensis (Sitka spruce in primary succession may be reflected in specific belowground changes in bacterial community structure and nitrogen cycling related to the interaction of these two plants. We examined early successional alder-conditioned soils in a glacial forefield to delineate how alders alter the soil microbial community with increasing dominance. Further, we assessed the impact of late-successional spruce plants on these early successional alder-conditioned microbiomes and related nitrogen cycling through a leachate addition microcosm experiment. We show how increasingly abundant alder select for particular bacterial taxa. Additionally, we found that spruce leachate significantly alters the composition of these microbial communities in large part by driving declines in taxa that are enriched by alder, including bacterial symbionts. We found these effects to be spruce specific, beyond a general leachate effect. Our work also demonstrates a unique influence of spruce on ammonium availability. Such insights bolster theory relating the importance of plant–microbe interactions with late-successional plants and interspecific plant interactions more generally.

Catalytic Asymmetric Total Synthesis of (+)- and (-)-Paeoveitol via a Hetero-Diels-Alder Reaction.

Science.gov (United States)

Li, Tian-Ze; Geng, Chang-An; Yin, Xiu-Juan; Yang, Tong-Hua; Chen, Xing-Long; Huang, Xiao-Yan; Ma, Yun-Bao; Zhang, Xue-Mei; Chen, Ji-Jun

2017-02-03

The first catalytic asymmetric total synthesis of (+)- and (-)-paeoveitol has been accomplished in 42% overall yield via a biomimetic hetero-Diels-Alder reaction. The chiral phosphoric acid catalyzed hetero-Diels-Alder reaction showed excellent diastereo- and enantioselectivity (>99:1 dr and 90% ee); two rings and three stereocenters were constructed in a single step to produce (-)-paeoveitol on a scale of 452 mg. This strategy enabled us to selectively synthesize both paeoveitol enantiomers from the same substrates by simply changing the enantiomer of the catalyst.

Intramolecular inverse electron demand Diels-Alder reactions of pyrimidines

NARCIS (Netherlands)

Frissen, A.E.

1990-01-01

This thesis deals with the intramolecular inverse electron demand Diels-Alder reaction of pyrimidines. The main objective of the study was to investigate the synthetic applicability of this reaction and to get more insight in the electronic and steric effects which determine the reactivity

DFT studies for the substituent effect on the diels-alder reaction of 1,4-diaza-1,3-butadienes

International Nuclear Information System (INIS)

Lee, Gab Yong

2001-01-01

DFT calculations have been performed on several substituted 1,4-diaza-1,3-butadienes (1,4-DABs) with electron donating and withdrawing groups at the terminal two nitrogens to investigate the reactivity of Diels-Alder reaction with acrolein. The calculated FMO (Frontier Molecular orbital) energies for the optimized 1,4-disubstituted-1,4DABs have been used to explain both normal and inverse electron demand Diels-Alder reactions. It is shown that the electron donating and withdrawing substituents lead to the normal(HOMO diene controlled) and inverse electron demand (LUMO diene controlled) Diels-Alder reactions, respectively

Biodegradable hyaluronic acid hydrogels to control release of dexamethasone through aqueous Diels–Alder chemistry for adipose tissue engineering

Energy Technology Data Exchange (ETDEWEB)

Fan, Ming; Ma, Ye; Zhang, Ziwei; Mao, Jiahui [School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing (China); Tan, Huaping, E-mail: hptan@njust.edu.cn [School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing (China); Hu, Xiaohong [School of Material Engineering, Jinling Institute of Technology, Nanjing (China)

2015-11-01

A robust synthetic strategy of biopolymer-based hydrogels has been developed where hyaluronic acid derivatives reacted through aqueous Diels–Alder chemistry without the involvement of chemical catalysts, allowing for control and sustain release of dexamethasone. To conjugate the hydrogel, furan and maleimide functionalized hyaluronic acid were synthesized, respectively, as well as furan functionalized dexamethasone, for the covalent immobilization. Chemical structure, gelation time, morphologies, swelling kinetics, weight loss, compressive modulus and dexamethasone release of the hydrogel system in PBS at 37 °C were studied. The results demonstrated that the aqueous Diels–Alder chemistry provides an extremely selective reaction and proceeds with high efficiency for hydrogel conjugation and covalent immobilization of dexamethasone. Cell culture results showed that the dexamethasone immobilized hydrogel was noncytotoxic and preserved proliferation of entrapped human adipose-derived stem cells. This synthetic approach uniquely allows for the direct fabrication of biologically functionalized gel scaffolds with ideal structures for adipose tissue engineering, which provides a competitive alternative to conventional conjugation techniques such as copper mediated click chemistry. - Highlights: • A biodegradable hyaluronic acid hydrogel was crosslinked via aqueous Diels–Alder chemistry. • Dexamethasone was covalently immobilized into the hyaluronic acid hydrogel via aqueous Diels–Alder chemistry. • Dexamethasone could be released from the Diels–Alder hyaluronic acid hydrogel in a controlled fashion.

Biodegradable hyaluronic acid hydrogels to control release of dexamethasone through aqueous Diels–Alder chemistry for adipose tissue engineering

International Nuclear Information System (INIS)

Fan, Ming; Ma, Ye; Zhang, Ziwei; Mao, Jiahui; Tan, Huaping; Hu, Xiaohong

2015-01-01

A robust synthetic strategy of biopolymer-based hydrogels has been developed where hyaluronic acid derivatives reacted through aqueous Diels–Alder chemistry without the involvement of chemical catalysts, allowing for control and sustain release of dexamethasone. To conjugate the hydrogel, furan and maleimide functionalized hyaluronic acid were synthesized, respectively, as well as furan functionalized dexamethasone, for the covalent immobilization. Chemical structure, gelation time, morphologies, swelling kinetics, weight loss, compressive modulus and dexamethasone release of the hydrogel system in PBS at 37 °C were studied. The results demonstrated that the aqueous Diels–Alder chemistry provides an extremely selective reaction and proceeds with high efficiency for hydrogel conjugation and covalent immobilization of dexamethasone. Cell culture results showed that the dexamethasone immobilized hydrogel was noncytotoxic and preserved proliferation of entrapped human adipose-derived stem cells. This synthetic approach uniquely allows for the direct fabrication of biologically functionalized gel scaffolds with ideal structures for adipose tissue engineering, which provides a competitive alternative to conventional conjugation techniques such as copper mediated click chemistry. - Highlights: • A biodegradable hyaluronic acid hydrogel was crosslinked via aqueous Diels–Alder chemistry. • Dexamethasone was covalently immobilized into the hyaluronic acid hydrogel via aqueous Diels–Alder chemistry. • Dexamethasone could be released from the Diels–Alder hyaluronic acid hydrogel in a controlled fashion

Niobium(V) chloride as catalyst in Diels-Alder reaction of furan ring

International Nuclear Information System (INIS)

Santos, Deborah A. dos; Rodrigues, Ludmila R.; Arpini, Bruno H.; Lacerda Junior, Valdemar; Greco, Sandro J.; Santos, Reginaldo B. dos; Neto, Alvaro C.; Castro, Eustaquio V.R. de

2014-01-01

According to the relevant literature, the Diels-Alder reaction of furan without a catalyst can last several weeks and shows a low yield due to the diene’s low reactivity. The use of Lewis acid catalysts or high pressures is described as an effective method for improving the reaction yields. This paper describes our recent study on the use of niobium pentachloride as the catalyst in Diels-Alder reactions between furan and several reactive dienophiles, among which methyl acrylate showed good yields, especially at lower temperatures. Other dienophiles have shown lower yields because of problems such as byproduct formation and the high reversibility of the reaction. (author)

Niobium(V) chloride as catalyst in Diels-Alder reaction of furan ring

Energy Technology Data Exchange (ETDEWEB)

Santos, Deborah A. dos; Rodrigues, Ludmila R.; Arpini, Bruno H.; Lacerda Junior, Valdemar; Greco, Sandro J.; Santos, Reginaldo B. dos; Neto, Alvaro C.; Castro, Eustaquio V.R. de, E-mail: vljuniorqui@gmail.com [Universidade Federal do Espirito Santo (UFES), Vitoria, ES (Brazil). Dept. de Quimica; Romao, Wanderson [Instituto Federal de Educacao, Ciencia e Tecnologia (IFES), Vila Velha, ES (Brazil)

2014-05-15

According to the relevant literature, the Diels-Alder reaction of furan without a catalyst can last several weeks and shows a low yield due to the diene’s low reactivity. The use of Lewis acid catalysts or high pressures is described as an effective method for improving the reaction yields. This paper describes our recent study on the use of niobium pentachloride as the catalyst in Diels-Alder reactions between furan and several reactive dienophiles, among which methyl acrylate showed good yields, especially at lower temperatures. Other dienophiles have shown lower yields because of problems such as byproduct formation and the high reversibility of the reaction. (author)

High stereoselectivity on low temperature Diels-Alder reactions

Directory of Open Access Journals (Sweden)

Invernize Paulo

2005-12-01

Full Text Available Abstract We have found that some of the usually poor dienophiles (2-cycloenones can undergo Diels-Alder reaction at -78°C with unusually high stereoselectivity in the presence of niobium pentachloride as a Lewis acid catalyst. A remarkable difference in reaction rates for unsubstituted and α- or β-methyl substituted 2-cycloenones was also observed.

Characterization and kinetic study of Diels-Alder reaction: Detailed study on N-phenylmaleimide and furan based benzoxazine with potential self-healing application

Directory of Open Access Journals (Sweden)

Z. Stirn

2016-07-01

Full Text Available The Diels-Alder reaction between N-phenylmaleimide and benzoxazine bearing furan group was investigated for the purpose of successful appliance of self-healing in benzoxazine polymer networks. The reaction as a function of temperature/time was performed in molten state and in a solution, where also the kinetic study was performed. The Diels-Alder reaction leads to a mixture of two diastereomers: endo presented at lower cyclo-reversion temperature and exo at higher. Therefore, the conversion rates and exo/endo ratio were studied in detail for both systems. For instance, in molten state the Diels-Alder reaction was triggered by the temperature of the melting point at 60 °C with exo/endo ratio preferable to the endo adduct. The study of the kinetics in a solution revealed that the Diels-Alder reaction followed typical bimolecular reversible second-order reaction. The activation energies were close to the previous literature data; 48.4 and 51.9 kJ·mol–1 for Diels-Alder reaction, and 91.0 and 102.3 kJ·mol–1 for retro-Diels-Alder reaction, in acetonitrile and chloroform, respectively. The reaction equilibrium in a solution is much more affected by the retro-Diels-Alder reaction than in a molten state. This study shows detailed investigation of DA reaction and provides beneficial knowledge for further use in self-healing polymer networks.

Thermoplastic-thermosetting merged polyimides via furan-maleimide Diels–Alder polymerization

Directory of Open Access Journals (Sweden)

Yogesh S. Patel

2017-02-01

Full Text Available Novel thermoplastic-thermosetting merged polyimide system has been developed via Diels–Alder intermolecular polymerization of bisfuran namely, 2,5-bis(furan-2-ylmethylcarbamoyl terephthalic acid A with a series of bismaleimides B1–4. Thus obtained intermediate Diels–Alder adducts C1–4 were aromatized and imidized (i.e. cyclized through carboxylic and amide groups to afford thermoplastic-thermosetting merged polyimides D1–4. Bisfuran A was prepared by the condensation of pyromellitic dianhydride with furan-2-ylmethanamine and characterized by elemental, spectral, thermal and LCMS analyses. Synthesized Diels–Alder adducts C1–4 and polyimides D1–4 were characterized by elemental analysis, spectral features, number average molecular weight (Mn‾, degree of polymerization (DP and thermal analysis. To facilitate the correct structural assessment and to be able to verify the occurrence of the DA adducts and PIs, a model compound 4 was prepared from phthalic anhydride and furan-2-ylmethanamine in a similar way. FTIR spectral features of polyimides D1–4 were compared with model compound 4 and they were found to be quite identical. The ‘in situ' void-free glass fiber reinforced composites GFRC1–4 were prepared from the produced system and characterized by chemical, mechanical and electrical analyses. All the composites showed good mechanical, electrical and thermal properties and good resistance to organic solvents and mineral acids.

Catalytic asymmetric diels-alder reaction of quinone imine ketals: a site-divergent approach.

Science.gov (United States)

Hashimoto, Takuya; Nakatsu, Hiroki; Maruoka, Keiji

2015-04-07

The catalytic asymmetric Diels-Alder reaction of quinone imine ketals with diene carbamates catalyzed by axially chiral dicarboxylic acids is reported herein. A variety of primary and secondary alkyl-substituted quinone derivatives which have not been applied in previous asymmetric quinone Diels-Alder reactions could be employed using this method. More importantly, we succeeded in developing a strategy to divert the reaction site in unsymmetrical 3-alkyl quinone imine ketals from the inherently favored unsubstituted C=C bond to the disfavored alkyl-substituted C=C bond. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Unsaturated aldehydes as alkene equivalents in the Diels-Alder reaction

DEFF Research Database (Denmark)

Taarning, Esben; Madsen, Robert

2008-01-01

A one-pot procedure is described for using alpha,beta-unsaturated aldehydes as olefin equivalents in the Diels-Alder reaction. The method combines the normal electron demand cycloaddition with aldehyde dienophiles and the rhodium-catalyzed decarbonylation of aldehydes to afford cyclohexenes...

Intramolecular Diels-Alder Reactions in Organic Synthesis

OpenAIRE

Sizemore, Nicholas Blandford Luke

2014-01-01

Intramolecular Diels-Alder (IMDA) reactions are an important class of reactions in synthetic organic chemistry for the rapid construction of polycyclic frameworks. Three classes of IMDA reactions were investigated synthetically and computationally: 1) all-carbon type 1 IMDA reactions, 2) N-acylnitroso type 2 IMDA reactions, and 3) cyano-azadiene IMDA reactions. The first class was implemented in research toward the total synthesis of maoecrystal Z and isopalhinine A. The second class was stud...

Quinine-Promoted, Enantioselective Boron-Tethered Diels-Alder Reaction by Anomeric Control of Transition State Conformation.

Science.gov (United States)

Scholl, Katie; Dillashaw, John; Timpy, Evan; Lam, Yu-Hong; DeRatt, Lindsey; Benton, Tyler R; Powell, Jacqueline P; Houk, Kendall N; Morgan, Jeremy B

2018-05-01

Diels-Alder reactions of tethered vinyl-metal species offer the opportunity to fashion highly functionalized diol intermediates for synthesis. We have developed the first enantioselective boron-tethered Diels-Alder reaction using quinine as a chiral promoter. Quinine recovery, enantioselectivity enhancement, and manipulation of the cyclohexene core are also investigated. DFT modeling calculations confirm the role of quinine as a bidentate ligand enhancing reaction rates. The enantioselectivity of the cycloaddition is proposed to originate from a boron-centered anomeric effect.

Well-defined Polymethylene-Based Co/Terpolymers by Combining Anthracene/Maleimide Diels-Alder Reaction with Polyhomologation

KAUST Repository

Hadjichristidis, Nikolaos

2015-05-26

A novel strategy towards well-defined polymethylene-based co/terpolymers, by combining anthracene/maleimide Diels-Alder reaction with polyhomologation, is presented. For the synthesis of diblock copolymers the following approach was applied: a) synthesis of α-anthracene-ω-hydroxy- polymethylene by polyhomologation using tri (9-anthracene-methyl propyl ether) borane as initiator, b) synthesis of furan-protected-maleimide-terminated poly (ε-caprolactone) or polyethylene glycol and c). Diels-Alder reaction between the anthracene and maleimide-terminated polymers. In the case of triblock terpolymers the α-anthracene-ω-hydroxy-polymethylene was used as macroinitiator for the ring-opening polymerization of D, L-lactide to afford an anthracene-terminated PM-b-PLA copolymer, followed by Diels-Alder reaction with furan-protected maleimide-terminated poly (ε-caprolactone) or polyethylene glycol to give the triblock terpolymers. All intermediate and final products were characterized by SEC, 1H NMR, UV-VIS spectroscopy and DSC.

Total Synthesis of (+)-Cytosporolide A via a Biomimetic Hetero-Diels-Alder Reaction.

Science.gov (United States)

Takao, Ken-Ichi; Noguchi, Shuji; Sakamoto, Shu; Kimura, Mizuki; Yoshida, Keisuke; Tadano, Kin-Ichi

2015-12-23

The first total synthesis of (+)-cytosporolide A was achieved by a biomimetic hetero-Diels-Alder reaction of (-)-fuscoatrol A with o-quinone methide generated from (+)-CJ-12,373. The dienophile, highly oxygenated caryophyllene sesquiterpenoid (-)-fuscoatrol A, was synthesized from the synthetic intermediate in our previous total synthesis of (+)-pestalotiopsin A. The o-quinone methide precursor, isochroman carboxylic acid (+)-CJ-12,373, was synthesized through a Kolbe-Schmitt reaction and an oxa-Pictet-Spengler reaction. The hetero-Diels-Alder reaction of these two compounds proceeded with complete chemo-, regio-, and stereoselectivity to produce the complicated pentacyclic ring system of the cytosporolide skeleton. This total synthesis unambiguously demonstrates that natural cytosporolide A has the structure previously suggested.

Synthesis of a Phlorin from a Meso-Fused Anthriporphyrin by a Diels-Alder Strategy.

Science.gov (United States)

Aslam, Adil S; Hong, Jung-Ho; Shin, June-Ho; Cho, Dong-Gyu

2017-12-18

An anthracene-containing meso-fused carbaporphyrin, which has extended π-conjugation pathways as compared to the corresponding naphthalene-containing carbaporphyrin, has been synthesized. The weak global aromaticity of the anthriporphyrin also allowed its use as the diene for a Diels-Alder reaction with dimethyl acetylenedicarboxylate (DMAD). The resulting phlorin contains an interesting bicyclic structure. Moreover, to the best of our knowledge, this phlorin is the first Diels-Alder adduct of a diene forming part of the global π-conjugation pathway of an aromatic porphyrinoid. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Widespread Expansion of Boreal Shrublands in the Siberian Low Arctic Is Linked to Cryogenic Disturbance and Geomorphology

Science.gov (United States)

Frost, G. V.; Epstein, H. E.; Walker, D. A.

2012-12-01

Declassified imagery from the KH-4B "Corona" and KH-7 "Gambit" Cold War satellite surveillance systems (1963-1972) are a unique, high-resolution dataset that establishes a baseline for landcover-change studies in the Russian Arctic spanning 6 decades. We co-registered Corona/Gambit and modern high-resolution imagery for seven ~65 km2 Low Arctic sites in northwest Siberia and Chukotka and quantified changes in the extent of tall shrublands dominated by Siberian alder (Alnus fruticosa) using a point-intercept sampling approach. We made ground observations at two sites to identify important geomorphic processes and physiographic units associated with shrub expansion. Alder shrubland cover increased at all sites; relative to the 1960s extent, shrubland extent increased by 5-31% at the northwest Siberian sites and by 9% at both Chukotkan sites,. In northwest Siberia, alder expansion was closely linked to cryogenic disturbances related to patterned-ground and active-layer detachments. At the Chukotkan sites, most alder expansion occurred on hillslope colluvium and floodplains; we also observed modest increases in Siberian dwarf pine (Pinus pumila). The close correspondence between expanding shrub patches and disturbance processes indicates that sparsely-vegetated, mineral-rich seedbeds strongly facilitate alder recruitment, and that the spatio-temporal attributes of disturbance mechanisms are a key determinant of landscape susceptibility to shrub expansion. Shrub expansion, in turn, initiates a cascade of effects on permafrost thermal regime and disturbance, promoting the accumulation of biomass and potentially buffering permafrost from climate warming.; Recently-established alder shrubs growing on non-sorted circles in patterned ground near Obskaya, northwest Siberia.

Biomass of Speckled Alder on an Air-Polluted Mountain Site and its Response to Fertilization

Czech Academy of Sciences Publication Activity Database

Kuneš, I.; Baláš, M.; Koňasová, T.; Špulák, O.; Balcar, V.; Bednářová Millerová, K.; Kacálek, D.; Jakl, M.; Zahradník, D.; Vítámvás, J.; Šťastná, J.; Jaklová Dytrtová, Jana

2014-01-01

Roč. 54, č. 6 (2014), s. 1421-1433 ISSN 0364-152X Grant - others:GA MZe(CZ) QH92087 Institutional support: RVO:61388963 Keywords : Alnus incana * site amelioration * biological amelioration * slow-acting amendments * ecosystem restoration Subject RIV: GK - Forestry Impact factor: 1.724, year: 2014

Alnuheptanoid B: A new Cyclic Diarylheptanoid from Alnus japonica Stem Bark

Directory of Open Access Journals (Sweden)

Sabrin R.M. Ibrahim

2016-05-01

Full Text Available A new cyclic diarylheptanoid namely alnuheptanoid B (3, along with four known cyclic diarylheptanoids: myricanone (1, (+-S-myricanol (2, myricanone 5-O- b -D-glucopyranoside (4, and (+-S-myricanol 5-O- b -D-glucopyranoside (5 were isolated from Alnus japonica Steud (Betulaceae stem bark. Their structures were determined by spectroscopic analyses, including UV, IR, 1D ( 1H and 13C, 2D (COSY, HMQC, and HMBC, and HRESIMS, as well as optical rotation measurement. Compounds 1, 2, 4, and 5 are reported for the first time from the plant. All isolated compounds 1-5 were tested for their antioxidant and anti-inflammatory activities using DPPH assay and carrageenin induced rat paw edema model, respectively. They displayed significant antioxidant activity in relation to propyl gallate (positive control. Compound 2 demonstrated anti-inflammatory effect at a dose 10 mg/kg.

Thermally reversible rubber-toughened thermoset networks via Diels-Alder chemistry

NARCIS (Netherlands)

Araya-Hermosilla, R.; Fortunato, G.; Pucci, A.; Raffa, P.; Polgar, L.; Broekhuis, A. A.; Pourhossein, P.; Lima, G. M. R.; Beljaars, M.; Picchioni, F.

In this work we present a reversible and toughened thermoset system based on the covalent incorporation of a furane functionalized ethylene-propylene rubber (EPM-Fu) into a thermoset furane functionalized polyketone (PK-Fu) via Diels-Alder (DA) reversible cross-linking with bismaleimide (b-MA).

Synthesis of the AB ring system of clifednamide utilizing Claisen rearrangement and Diels-Alder reaction as key steps.

Science.gov (United States)

Loke, Inga; Bentzinger, Guillaume; Holz, Julia; Raja, Aruna; Bhasin, Aman; Sasse, Florenz; Köhn, Andreas; Schobert, Rainer; Laschat, Sabine

2016-01-21

In order to construct the functionalized AB ring system of clifednamide, member of the class of macrocyclic tetramic acid lactams, a synthesis was developed which utilized an Ireland-Claisen rearrangement and an intramolecular Diels-Alder reaction. Starting from di-O-isopropylidene-d-mannitol the allyl carboxylate precursor for the sigmatropic rearrangement was prepared. This rearrangement proceeded diastereoselectively only in the presence of an allyl silyl ether instead of the parent enone in the side chain, as suggested by deuteration experiments. A subsequent Diels-Alder reaction yielded the target ethyl hexahydro-1H-indene-carboxylate with high diastereoselectivity. Quantum-chemical investigations of this intramolecular Diels-Alder reaction support the proposed configuration of the final product.

A Diels-Alder Reaction Conducted Within the Parameters of Aqueous Organocatalysis: Still Just Smoke and Mirrors

Science.gov (United States)

Stowe, G. Neil

2010-01-01

Conducting reactions using water as solvent is a highly prized goal for the organic chemist. Based upon recent literature and our continuing interest in the field of aqueous organocatalysis, we tested the scope of an enamine based Diels-Alder reaction using (±)-nornicotine, proline and a proline derivative as aqueous organocatalysts. Unfortunately, none of the examined catalysts under aqueous conditions proved useful, leaving the aqueous Diels-Alder reaction as an elusive goal. PMID:21516231

Efficient Diels-Alder reaction of 1,2-benzoquinones with arynes and its utility in one-pot reactions.

Science.gov (United States)

Kaicharla, Trinadh; Bhojgude, Sachin Suresh; Biju, Akkattu T

2012-12-21

A new protocol for the efficient Diels-Alder reaction of 1,2-benzoquinones with arynes is reported. The aryne generated by the fluoride-induced 1,2-elimination of 2-(trimethylsilyl)aryl triflates undergoes a facile Diels-Alder reaction with 1,2-benzoquinones, affording the dioxobenzobicyclooctadienes in moderate to excellent yields. In addition, this methodology has been applied to the one-pot synthesis of benzoquinoxalinobarrelene and naphthalene derivatives.

Tall shrub expansion facilitated by patterned ground in the northwest Siberian Low Arctic

Science.gov (United States)

Frost, G. V.; Epstein, H. E.; Walker, D. A.; Matyshak, G.; Ermokhina, K.

2011-12-01

We integrated field observations with a time-series of satellite imagery to identify key biophysical attributes associated with tall shrub expansion and increased vegetation productivity within a forest-tundra ecotone near Kharp, northwest Siberia. Comparison of high-resolution Corona and QuickBird satellite photography indicates that alder (Alnus fruticosa) cover increased by ~10% since 1968. Additionally, areas of sharply increasing productivity detected using a Landsat TM/ETM+ time-series for 1985-2009 are consistently co-located with expanding shrub stands. Field observations made in 2011 revealed that most of the shrub expansion has occurred in areas of patterned ground in which abundant mineral-dominated microsites ("circles") have been maintained by cryogenic disturbance. In order to test whether shrub expansion was facilitated by circles, we established a series of transects according to categories of alder stand age and circle density. Along the transects, we mapped the location of alders and circles, measured soil organic depth and leaf area index (LAI), and characterized plant communities. In recent expansion areas, young alders occur almost exclusively on silt-rich circles that lack vegetation and surface organic matter. Alder abundance and LAI increased with the total area occupied by exposed circles. Analyses using spatial statistics indicate that young alders tend to occur in evenly-spaced groups that mirror the spacing of circles. This distribution pattern persists in older alder stands, especially where circles are large and widely-spaced. Stands on closely-spaced circles quickly develop dense canopies and low species-diversity. Based on ground- and satellite-based observations, we conclude that the abundance of mineral-dominated circles at Kharp has facilitated rapid alder expansion and associated alterations in plant community structure, composition, and productivity. Physical processes in areas of patterned ground promote continuous, rather than

Diels-Alder reactions of anthracenes with C-sulfonyldithioformates

DEFF Research Database (Denmark)

El-Sayed, I.; Ali, O.M.; Fischer, A.

2003-01-01

C-Sulfonyldithioformates (2) (R-1 = ArSO2, R 2 = ArS) readily add to anthracene and 9-methylanthracene (1) in a Diels-Alder fashion with formation of 9,10-dihydro-10,9-(epithiomethano)anthracenes (3) which in turn may suffer thermally induced elimination of arenesulfinic acid to yield the 9......-anthracenedithiocarboxylic esters (4). The reactions with the unsymmetrical diene 9-methylanthracene take place in a highly stereoselective fashion....

Medium-Ring Effects on the Endo/Exo Selectivity of the Organocatalytic Intramolecular Diels-Alder Reaction.

Science.gov (United States)

Hooper, Joel F; James, Natalie C; Bozkurt, Esra; Aviyente, Viktorya; White, Jonathan M; Holland, Mareike C; Gilmour, Ryan; Holmes, Andrew B; Houk, K N

2015-12-18

The intramolecular Diels-Alder reaction has been used as a powerful method to access the tricyclic core of the eunicellin natural products from a number of 9-membered-ring precursors. The endo/exo selectivity of this reaction can be controlled through a remarkable organocatalytic approach, employing MacMillan's imidazolidinone catalysts, although the mechanistic origin of this selectivity remains unclear. We present a combined experimental and density functional theory investigation, providing insight into the effects of medium-ring constraints on the organocatalyzed intramolecular Diels-Alder reaction to form the isobenzofuran core of the eunicellins.

Asymmetric Catalytic Aza-Diels-Alder/Ring-Closing Cascade Reaction Forming Bicyclic Azaheterocycles by Trienamine Catalysis.

Science.gov (United States)

Li, Yang; Barløse, Casper; Jørgensen, Julie; Carlsen, Bjørn Dreiø; Jørgensen, Karl Anker

2017-01-01

An asymmetric catalytic aza-Diels-Alder/ring-closing cascade reaction between acylhydrazones and in situ formed trienamines is presented. The reaction proceeds through a formal aza-Diels-Alder cycloaddition, followed by a ring-closing reaction forming the hemiaminal ring leading to chiral bicyclic azaheterocycles in moderate to good yield (up to 71 %), good enantio- (up to 92 % ee) and diastereoselectivity (up to >20:1 d.r.). Furthermore, transformations are presented to show the potential application of the formed product. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Asymmetric Formal Aza-Diels-Alder Reaction of Trifluoromethyl Hemiaminals with Enones Catalyzed by Primary Amines.

Science.gov (United States)

Zhang, Sheng; Cha, Lide; Li, Lijun; Hu, Yanbin; Li, Yanan; Zha, Zhenggen; Wang, Zhiyong

2016-04-15

A primary amine-catalyzed asymmetric formal aza-Diels-Alder reaction of trifluoromethyl hemiaminals with enones was developed via a chiral gem-diamine intermediate. This novel protocol allowed facile access to structurally diverse trifluoromethyl-substituted piperidine scaffolds with high stereoselectivity. The utility of this method was further demonstrated through a concise approach to biologically active 4-hydroxypiperidine. More importantly, a stepwise mechanism involving an asymmetric induction process was proposed to rationalize the positive correlation between the chirality of the gem-diamine intermediate and the formal aza-Diels-Alder product.

TALL HERB SPRUCE FORESTS AS CLIMAX COMMUNITIES ON LOWLAND SWAMPS OF BRYANSK POLESIE

Directory of Open Access Journals (Sweden)

O. I. Evstigneev

2017-09-01

Full Text Available Nettle grey alder forests are a dominant forest type on lowland swamps in the Bryansk Polesie. They are formed as a result of repeated cuttings in the place of tall herb spruce forests. Tall herb spruce forests are very rare communities in the vegetation cover in this area due to clear cutting, melioration and peat extraction. An assessment of the succession status of tall herb spruce forests and nettle grey alder forests was carried out in this paper. The criteria of climax state and succession state of communities, developed for Eastern European forests, were used. These criteria are based on the degree of intensity of the following signs in the community: 1 the completeness of species composition of tree synusia; 2 the ontogenetic structure of tree species cenopopulation; 3 the gap-mosaic stand structure; 4 the diversity of microsites in soil cover; 5 the completeness of species composition and ecological-coenotic diversity of vascular species. We showed that tall herb spruce forest, as opposed to black alder forest, is close to communities of the climax type. This is evidenced by the following features of cenosis: firstly, all tree species in the area that covers the Bryansk Polesie and that are able to grow on lowland swamps are represented in the spruce forest (Alnus glutinosa, Betula pubescens, Fraxinus excelsior, Padus avium, Picea abies, Salix pentandra, Sorbus aucuparia, Ulmus glabra. Secondly, a steady turnover of generations is carried out in the cenopopulations of main edificators (Picea abies and Alnus glutinosa. This is evidenced by the complete and left-sided structure of their ontogenetic spectrum. Thirdly, a system of asynchronously developing gaps (parcels, which are formed on the site of old tree falls, is formed in the community. This ensures the continuous renewal of spruce and alder populations and creates conditions for the regeneration of other tree species. Fourthly, the structure of biogenic microsites has been formed

Synthesis and Diels–Alder cycloaddition reaction of norbornadiene and benzonorbornadiene dimers

Directory of Open Access Journals (Sweden)

Bilal Nişancı

2009-08-01

Full Text Available Dimeric forms of norbornadiene and benzonorbornadiene were synthesized starting with known monobromide derivatives. The Diels–Alder cycloaddition reaction of dimers with TCNE and PTAD was investigated and new norbornenoid polycyclics were obtained. All compounds were characterized properly using NMR spectroscopy.

Recent applications of intramolecular Diels-Alder reactions to natural product synthesis

DEFF Research Database (Denmark)

Juhl, M.; Tanner, David Ackland

2009-01-01

This tutorial review presents some recent examples of intramolecular Diels-Alder (IMDA) reactions as key complexity-generating steps in the total synthesis of structurally intricate natural products. The opportunities afforded by transannular (TADA) versions of the IMDA reaction in complex molecu...... comprehensive, reviews....

Diels-Alder reactions in water : Enforced hydrophobic interaction and hydrogen bonding

NARCIS (Netherlands)

Engberts, Jan B.F.N.

1995-01-01

Second-order rate constants have been measured for the Diels-Alder (DA) reactions of cyclopentadiene with dienophiles of varying hydrophobicity and hydrogen-bond acceptor capacity in water, in a series of organic solvents and in alcohol-water mixtures. The intramolecular DA reaction of

DIELS-ALDER REACTIONS IN WATER - ENFORCED HYDROPHOBIC INTERACTION AND HYDROGEN-BONDING

NARCIS (Netherlands)

Engberts, J.B.F.N.

Second-order rate constants have been measured for the Diels-Alder (DA) reactions of cyclopentadiene with dienophiles of varying hydrophobicity and hydrogen-bond acceptor capacity in water, in a series of organic solvents and in alcohol-water mixtures. The intramolecular DA reaction of

Dietary Preference of Gammarus pulex and Asellus aquaticus during a Laboratory Breeding Programme for Ecotoxicological Studies

Directory of Open Access Journals (Sweden)

M. C. Bloor

2011-01-01

Full Text Available An investigation was undertaken to establish if Gammarus pulex and Asellus aquaticus preferred a diet of unconditioned, artificially or naturally conditioned alder leaves (Alnus glutinosa. Standardised, 24 hour ex situ feeding assays were undertaken with both species to determine their food preference. The results showed that A. aquaticus ate more leaf material compared to G. pulex (Z 23.909, P 0.001 when exposed to all three test variables. Also, both G. pulex and A. aquaticus demonstrated a preference for naturally conditioned leaves compared to the other two variables, with unconditioned leaves proving the least popular food option for both macroinvertebrates (Z 18.803, <0.001. However, both species ate varying amounts of all the leaf treatments (Z 136.399, <0.001. Subsequently, the author outlined a feeding methodology for natural alder leaf conditioning that could be used during a laboratory breeding programme.

Lewis acid catalysis of a Diels-Alder reaction in water

NARCIS (Netherlands)

Otto, S; Bertoncin, F; Engberts, JBFN

1996-01-01

Here we report the first detailed study of a Diels-Alder (DA) reaction that is catalyzed by Lewis acids in water. The effect of Co2+, Ni2+, Cu2+ and Zn2+ ions as Lewis acid catalysts on the rate and endo-exo selectivity of the DA reaction between the bidentate dienophiles

Chiral Pyridinium Phosphoramide as a Dual Brønsted Acid Catalyst for Enantioselective Diels-Alder Reaction.

Science.gov (United States)

Nishikawa, Yasuhiro; Nakano, Saki; Tahira, Yuu; Terazawa, Kanako; Yamazaki, Ken; Kitamura, Chitoshi; Hara, Osamu

2016-05-06

Chiral pyridinium phosphoramide 1·HX was designed to be a new class of chiral Brønsted acid catalyst in which both the pyridinium proton and the adjacent imide-like proton activated by the electron-withdrawing pyridinium moiety could work cooperatively as strong dual proton donors. The potential of 1·HX was shown in the enantioselective Diels-Alder reactions of 1-amino dienes with various dienophiles including N-unsubstituted maleimide, which has yet to be successfully used in an asymmetric Diels-Alder reaction.

Quantitative structure-activation barrier relationship modeling for Diels-Alder ligations utilizing quantum chemical structural descriptors.

Science.gov (United States)

Nandi, Sisir; Monesi, Alessandro; Drgan, Viktor; Merzel, Franci; Novič, Marjana

2013-10-30

In the present study, we show the correlation of quantum chemical structural descriptors with the activation barriers of the Diels-Alder ligations. A set of 72 non-catalysed Diels-Alder reactions were subjected to quantitative structure-activation barrier relationship (QSABR) under the framework of theoretical quantum chemical descriptors calculated solely from the structures of diene and dienophile reactants. Experimental activation barrier data were obtained from literature. Descriptors were computed using Hartree-Fock theory using 6-31G(d) basis set as implemented in Gaussian 09 software. Variable selection and model development were carried out by stepwise multiple linear regression methodology. Predictive performance of the quantitative structure-activation barrier relationship (QSABR) model was assessed by training and test set concept and by calculating leave-one-out cross-validated Q2 and predictive R2 values. The QSABR model can explain and predict 86.5% and 80% of the variances, respectively, in the activation energy barrier training data. Alternatively, a neural network model based on back propagation of errors was developed to assess the nonlinearity of the sought correlations between theoretical descriptors and experimental reaction barriers. A reasonable predictability for the activation barrier of the test set reactions was obtained, which enabled an exploration and interpretation of the significant variables responsible for Diels-Alder interaction between dienes and dienophiles. Thus, studies in the direction of QSABR modelling that provide efficient and fast prediction of activation barriers of the Diels-Alder reactions turn out to be a meaningful alternative to transition state theory based computation.

Diels-Alder Reactions in Water. Effects of Hydrophobicity and Hydrogen Bonding

NARCIS (Netherlands)

Otto, Sijbren; Blokzijl, Wilfried; Engberts, Jan B.F.N.

1994-01-01

In order to check whether the activated complex for the Diels-Alder reactions of 5-substituted 1,4-naphthoquinones with cyclopentadiene is more polar in water than in other solvents, we have determined the substituent effects in seven different solvents. The substituent effects gradually decrease

Micellar Catalysis of Diels-Alder Reactions : Substrate Positioning in the Micelle

NARCIS (Netherlands)

Rispens, Theo; Engberts, Jan B.F.N.

2002-01-01

We have studied the kinetics of the Diels-Alder reactions of cyclopentadiene, sorbyl alcohol, and sorbyltrimethylammonium bromide with a series of N-substituted maleimides in micellar media. Micellar rate constants have been determined and were found to be 20-40 times lower than the respective

New Insights into the Diels-Alder Reaction of Graphene Oxide.

Science.gov (United States)

Brisebois, Patrick P; Kuss, Christian; Schougaard, Steen B; Izquierdo, Ricardo; Siaj, Mohamed

2016-04-18

Graphene oxide is regarded as a major precursor for graphene-based materials. The development of graphene oxide based derivatives with new functionalities requires a thorough understanding of its chemical reactivity, especially for canonical synthetic methods such as the Diels-Alder cycloaddition. The Diels-Alder reaction has been successfully extended with graphene oxide as a source of diene by using maleic anhydride as a dienophile, thereby outlining the presence of the cis diene present in the graphene oxide framework. This reaction provides fundamental information for understanding the exact structure and chemical nature of graphene oxide. On the basis of high-resolution (13) C-SS NMR spectra, we show evidence for the formation of new sp(3) carbon centers covalently bonded to graphene oxide following hydrolysis of the reaction product. DFT calculations are also used to show that the presence of a cis dihydroxyl and C vacancy on the surface of graphene oxide are promoting the reaction with significant negative reaction enthalpies. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Diels-Alder cycloaddition strategy for kinetic resolution of chiral pyrazolidinones.

Science.gov (United States)

Sibi, Mukund P; Kawashima, Keisuke; Stanley, Levi M

2009-09-03

A rare example of the application of a catalytic, enantioselective Diels-Alder cycloaddition to affect a kinetic resolution has been developed. Chiral pyrazolidinones are resolved with high selectivity through a process that utilizes a relay of stereochemical information from a permanent chiral center to a fluxional chiral center to enhance the inherent selectivity of the chiral Lewis acid catalyst.

Deeper Insight into the Diels-Alder Reaction through the Activation Strain Model

NARCIS (Netherlands)

Fernandez, I.; Bickelhaupt, F.M.

2016-01-01

The Diels–Alder (DA) cycloaddition reaction has the ability to significantly increase molecular complexity regioselectively and stereospecifically in a single synthetic step. In this review it is discussed how the activation strain model of chemical reactivity reveals the physical factors that

Metal-catalyzed Asymmetric Hetero-Diels-Alder Reactions of Unactivated Dienes with Glyoxylates

DEFF Research Database (Denmark)

Johannsen, Mogens; Yao, Sulan; Graven, Anette

1998-01-01

The development of a catalytic asymmetric hetero-Diels-Alder methodology for the reaction of unactivated dienes with glyoxylates is presented. Several different asymmetric catalysts can be used, but copper-bisoxazolines and aluminium-BINOL give the highest yield, and the best chemo...

Synthesis of 3-Alkenyl-1-azaanthraquinones via Diels-Alder and Electron Transfer Reactions

Directory of Open Access Journals (Sweden)

Patrice Vanelle

2002-12-01

Full Text Available A convenient route to 3-alkenyl-1-azaanthraquinones via a hetero Diels-Alder reaction between an azadiene and naphthoquinone, a free radical chlorination and an electron transfer reaction is reported.

Two new polyploid species closely related to Alnus glutinosa in Europe and North Africa - An analysis based on morphometry, karyology, flow cytometry and microsatellites

Czech Academy of Sciences Publication Activity Database

Vít, Petr; Douda, Jan; Krak, Karol; Havrdová, Alena; Mandák, Bohumil

2017-01-01

Roč. 66, č. 3 (2017), s. 567-583 ISSN 0040-0262 R&D Projects: GA ČR(CZ) GAP504/11/0402 Institutional support: RVO:67985939 Keywords : Alnus glutinosa * flow cytometry * Balkan Peninsula Subject RIV: EF - Botanics OBOR OECD: Plant sciences, botany Impact factor: 2.447, year: 2016

Biotransformation of a cage-like diels-alder adduct and derivatives by Mucor ramosissimus samutsevitsch Biotransformação de um aduto de diels-alder cage-like e derivados por Mucor ramosissimus samutsevitsch

Directory of Open Access Journals (Sweden)

Felicia Megumi Ito

2009-09-01

Full Text Available The present study aimed to evaluate the ability for biotransformation of the Diels-Alder adduct tricyclo[6.2.1.0(2,7]undeca-4,9-dien-3,6-dione (1 and two synthetic derivatives by the saprobe fungus Mucor ramosissimus Samutsevitsch. Products from oxidation, isomerization and, regioselective and enantioselective reduction were achieved.Neste trabalho avaliou-se a capacidade de biotransformação do aduto de Diels-Alder triciclo[6.2.1.0(2-7]undeca-4,9-dien-3,6-diona (1 e dois derivados sintéticos pelo fungo sapróbio Mucor ramosissimus Samutsevitsch. Produtos de oxidação, isomerização e redução regiosseletiva e enantiosseletiva foram obtidos.

Photoreactive polymer brushes for high-density patterned surface derivatization using a Diels-Alder photoclick reaction.

Science.gov (United States)

Arumugam, Selvanathan; Orski, Sara V; Locklin, Jason; Popik, Vladimir V

2012-01-11

Reactive polymer brushes grown on silicon oxide surfaces were derivatized with photoreactive 3-(hydroxymethyl)naphthalene-2-ol (NQMP) moieties. Upon 300 or 350 nm irradiation, NQMP efficiently produces o-naphthoquinone methide (oNQM), which in turn undergoes very rapid Diels-Alder addition to vinyl ether groups attached to a substrate, resulting in the covalent immobilization of the latter. Any unreacted oNQM groups rapidly add water to regenerate NQMP. High-resolution surface patterning is achieved by irradiating NQMP-derivatized surfaces using photolithographic methods. The Diels-Alder photoclick reaction is orthogonal to azide-alkyne click chemistry, enabling sequential photoclick/azide-click derivatizations to generate complex surface functionalities. © 2011 American Chemical Society

Avoidance of nonhost plants by a bark beetle, Pityogenes bidentatus, in a forest of odors

Science.gov (United States)

Byers, John A.; Zhang, Qing-He; Birgersson, Göran

The bark beetle, Pityogenes bidentatus (Coleoptera: Scolytidae), searches in mixed conifer and deciduous forests of northern Europe for suitable branches of its host, Scots pine (Pinus sylvestris). We tested whether odors from several diverse nonhost trees and plants common in the habitat (e.g., mountain ash, Sorbus aucuparia; oak, Quercus robur; alder buckthorn, Frangula alnus; blueberry, Vaccinium myrtillus; raspberry, Rubus idaeus; and grass, Deschampsia flexuosa) would reduce the attraction of the bark beetle to traps releasing its aggregation pheromone components in the field. Volatiles from the leaves or bark of each of these plants significantly reduced the attraction of the beetles to their pheromone. Odors collected from these nonhosts and analyzed by GC/MS contained monoterpenes, sesquiterpenes, and ``green-leaf'' alcohols, several of which (e.g., 1-octene-3-ol and β-caryophyllene) reduced the attraction to pheromone in the field and elicited electroantennographic responses. In the laboratory, reproduction by the beetle was marginal in nonhost Norway spruce, Picea abies, and was absent in the other nonhost trees. Olfactory avoidance of unsuitable nonhosts may have evolved due to advantages in avoiding mistakes during host selection.

Regio-, Diastereo-, and Enantioselective Nitroso-Diels-Alder Reaction of 1,3-Diene-1-carbamates Catalyzed by Chiral Phosphoric Acids.

Science.gov (United States)

Pous, Jonathan; Courant, Thibaut; Bernadat, Guillaume; Iorga, Bogdan I; Blanchard, Florent; Masson, Géraldine

2015-09-23

Chiral phosphoric acid-catalyzed asymmetric nitroso-Diels-Alder reaction of nitrosoarenes with carbamate-dienes afforded cis-3,6-disubstituted dihydro-1,2-oxazines in high yields with excellent regio-, diastereo-, and enantioselectivities. Interestingly, we observed that the catalyst is able not only to control the enantioselectivity but also to reverse the regioselectivity of the noncatalyzed nitroso-Diels-Alder reaction. The regiochemistry reversal and asynchronous concerted mechanism were confirmed by DFT calculations.

Enantio- and Stereoselective Construction of Atisane Scaffold via Organocatalytic Intramolecular Michael Reaction and Diels-Alder Reaction.

Science.gov (United States)

Sekita, Hiroko; Adachi, Kyohei; Kobayashi, Ippei; Sato, Yusuke; Nakada, Masahisa

2017-05-05

An enantio- and stereoselective construction of the atisane scaffold via organocatalytic intramolecular Michael reaction and Diels-Alder reaction is described. The organocatalytic intramolecular Michael reaction has been found to stereoselectively generate a trans-stereodiad comprising an all-carbon quaternary and a tertiary stereogenic centers. Use of the chiral secondary amine bearing thiourea with benzoic acid as additive is the key to obtaining the desired product with excellent ee in synthetically acceptable yield. The prepared chiral building block has been successfully converted to the compound including the atisane scaffold via the highly stereoselective intramolecular Diels-Alder reaction.

Tandem Mannich/Diels–Alder reactions for the synthesis of indole compound libraries

DEFF Research Database (Denmark)

Wu, Peng; Petersen, Michael Åxman; Petersen, Rico

2016-01-01

A tandem Mannich/Diels–Alder sequence for the synthesis of small-molecule libraries with an indolyl-octahydro-3a,6-epoxy-isoindole core structure is demonstrated in this study. Representative diversification examples based on this scaffold were performed, and a library is being produced within...

Using chiral ionic liquid additives to enhance asymmetric induction in a Diels-Alder reaction.

Science.gov (United States)

Goodrich, P; Nimal Gunaratne, H Q; Hall, L; Wang, Y; Jin, L; Muldoon, M J; Ribeiro, A P C; Pombeiro, A J L; Pârvulescu, V I; Davey, P; Hardacre, C

2017-01-31

A bis-oxazoline ligand has been complexed using Cu(ii) and Zn(ii) trifluoromethanesulfonate and a range of chiral ionic liquid (CIL) additives based on natural products were used as a co-catalyst for a Diels-Alder reaction. The catalytic performance of these systems was compared for the asymmetric Diels-Alder reaction between N-acryloyloxazolidinone and cyclopentadiene with and without the presence of a CIL additive. In the absence of the CIL, both catalysts resulted in low enantioselectivities in conventional solvents and ionic liquids. However, whilst only a minor effect of the CIL was observed for the Cu based catalyst, in the case of the Zn based catalyst, significant enhancements in endo enantioselectivity of up to 50% were found on the addition of a CIL.

Application of Carbohydrate-Templated Asymmetric Diels-Alder Reaction to the Syntheses of ent-Penicillones A and B.

Science.gov (United States)

Weng, Chia-Hao; Hsu, Day-Shin; Liao, Chun-Chen

2016-11-18

Total syntheses of ent-penicillones A (ent-1) and B (ent-2) from 3,5-dimethylcatechol (3) were accomplished in 10 and 9 synthetic steps, respectively. A carbohydrate-templated asymmetric intramolecular Diels-Alder reaction of a masked o-benzoquinone (MOB) 9 and an aqueous acid-catalyzed intramolecular aldol reaction are the key synthetic steps. In addition, the absolute configurations of the bicyclo[2.2.2]oct-5-en-2-one core obtained from the per-O-benzylated α-d-glucopyranosyl as a carbohydrate template in the intramolecular Diels-Alder reaction of MOBs were revised.

alpha,beta-unsaturated 2-acyl imidazoles as a practical class of dienophiles for the DNA-Based catalytic asymmetric diels-alder reaction in water

NARCIS (Netherlands)

Boersma, A.J.; Feringa, B.L.; Roelfes, G.

2007-01-01

alpha,beta-Unsaturated 2-acyl imidazoles are a novel and practical class of dienophiles for the DNA-based catalytic asymmetric Diels-Alder reaction in water. The Diels-Alder products are obtained with very high diastereoselectivities and enantioselectivities in the range of 83-98%. The catalytic

The effect of limited availability of N or water on C allocation to fine roots and annual fine root turnover in Alnus incana and Salix viminalis.

Science.gov (United States)

Rytter, Rose-Marie

2013-09-01

The effect of limited nitrogen (N) or water availability on fine root growth and turnover was examined in two deciduous species, Alnus incana L. and Salix viminalis L., grown under three different regimes: (i) supply of N and water in amounts which would not hamper growth, (ii) limited N supply and (iii) limited water supply. Plants were grown outdoors during three seasons in covered and buried lysimeters placed in a stand structure and filled with quartz sand. Computer-controlled irrigation and fertilization were supplied through drip tubes. Production and turnover of fine roots were estimated by combining minirhizotron observations and core sampling, or by sequential core sampling. Annual turnover rates of fine roots water availability. Fine root production (treatments in Salix; i.e., absolute length and biomass production increased in the order: water limited treatment effects were detected for fine roots 1-2 mm. Proportionally more C was allocated to fine roots (≤2 mm) in N or water-limited Salix; 2.7 and 2.3 times the allocation to fine roots in the unlimited regime, respectively. Estimated input to soil organic carbon increased by ca. 20% at N limitation in Salix. However, future studies on fine root decomposition under various environmental conditions are required. Fine root growth responses to N or water limitation were less pronounced in Alnus, thus indicating species differences caused by N-fixing capacity and slower initial growth in Alnus, or higher fine root plasticity in Salix. A similar seasonal growth pattern across species and treatments suggested the influence of outer stimuli, such as temperature and light.

Deeper Insight into the Diels-Alder Reaction through the Activation Strain Model

NARCIS (Netherlands)

Fernandez, Israel; Bickelhaupt, F. Matthias

2016-01-01

In this Focus Review, we present the application of the so-called Activation Strain Model of chemical reactivity to the Diels–Alder cycloaddition reaction. To this end, representative recent examples have been selected to illustrate the power of this new computational approach to gain a deeper

Effects on the forest of sulfur dioxide from a sulfur fire near Edson, Alberta

Energy Technology Data Exchange (ETDEWEB)

Hocking, D

1975-01-01

Sulfur was burnt in a sanitary landfill during August 9 and 10, 1974. Resulting sulfur dioxide impinged on the surrounding mixed forest for 29 h. About 4 ha of forest displayed visible injury symptoms of varying intensity soon after. However, only .4 ha remained permanently injured the next season. Here, white spruce (Picea glauca (Moench) Voss) and scattered individuals of balsam poplar (Populus balsamifera L.), alder (Alnus tenuifolia Nutt.), and trembling aspen (Populus tremuloides Michx.) were killed. This report describes the extent of injury, relative sensitivities of affected plant species, and recovery in the spring in 1975.

Inhibition of the growth of Alexandrium tamarense by algicidal substances in Chinese fir (Cunninghamia lanceolata).

Science.gov (United States)

Yang, Wei-Dong; Liu, Jie-Sheng; Li, Hong-Ye; Zhang, Xin-Lian; Qi, Yu-Zao

2009-10-01

The wood sawdust from Chinese fir (Cunninghamia lanceolata) exhibited stronger inhibition on the growth of Alexandrium tamarense than those from alder (Alnus cremastogyne), pine (Pinus massoniana), birch (Betula alnoides) and sapele (Entandrophragma cylindricum). The water extract, acetone-water extract and essential oil from fir sawdust were all shown to inhibit the growth of A. tamarense. The inhibition of fir essential oil was the strongest among all the above wood sources while the half effective concentration was only 0.65 mg/L. These results suggested that the fir essential oil may play an important role in the algicidal effect of Chinese fir.

Mechanistic Insight into the Dehydro-Diels-Alder Reaction of Styrene-Ynes.

Science.gov (United States)

Kocsis, Laura S; Kagalwala, Husain N; Mutto, Sharlene; Godugu, Bhaskar; Bernhard, Stefan; Tantillo, Dean J; Brummond, Kay M

2015-12-04

The Diels-Alder reaction represents one of the most thoroughly studied and well-understood synthetic transformations for the assembly of six-membered rings. Although intramolecular dehydro-Diels-Alder (IMDDA) reactions have previously been employed for the preparation of naphthalene and dihydronaphthalene substrates, low yields and product mixtures have reduced the impact and scope of this reaction. Through the mechanistic studies described within, we have confirmed that the thermal IMDDA reaction of styrene-ynes produces a naphthalene product via loss of hydrogen gas from the initially formed cycloadduct, a tetraenyl intermediate. Alternatively, the dihydronaphthalene product is afforded from the same tetraenyl intermediate via a radical isomerization process. Moreover, we have identified conditions that can be used to achieve efficient, high-yielding, and selective IMDDA reactions of styrene-ynes to form either naphthalene or dihydronaphthalene products. The operational simplicity and retrosynthetic orthogonality of this method for the preparation of naphthalenes and dihydronaphthalenes makes this transformation appealing for the synthesis of medicinal and material targets. The mechanistic studies within may impact the development of other thermal transformations.

The Hexadehydro-Diels-Alder Cycloisomerization Reaction Proceeds by a Stepwise Mechanism.

Science.gov (United States)

Wang, Tao; Niu, Dawen; Hoye, Thomas R

2016-06-29

We report here experiments showing that the hexadehydro-Diels-Alder (HDDA) cycloisomerization reaction proceeds in a stepwise manner-i.e., via a diradical intermediate. Judicious use of substituent effects was decisive. We prepared (i) a series of triyne HDDA substrates that differed only in the R group present on the remote terminus of the diynophilic alkyne and (ii) an analogous series of dienophilic alkynes (n-C7H15COC≡CR) for use in classical Diels-Alder (DA) reactions (with 1,3-cyclopentadiene). The R groups were CF3, CHO, COMe/Et, CO2Me, CONMe2/Et2, H, and 1-propynyl. The relative rates of both the HDDA cyclization reactions and the simple DA cycloadditions were measured. The reactivity trends revealed a dramatic difference in the behaviors of the CF3 (slowest HDDA and nearly fastest DA) and 1-propynyl (fastest HDDA and slowest DA) containing members of each series. These differences can be explained by invoking radical-stabilizing energies rather than electron-withdrawing effects as the dominating feature of the HDDA reaction.

Domino Aza-Michael-ih-Diels-Alder Reaction to Various 3-Vinyl-1,2,4-triazines: Access to Polysubstituted Tetrahydro-1,6-naphthyridines.

Science.gov (United States)

Jouha, Jabrane; Buttard, Floris; Lorion, Magali; Berthonneau, Clément; Khouili, Mostafa; Hiebel, Marie-Aude; Guillaumet, Gérald; Brière, Jean-François; Suzenet, Franck

2017-09-15

A straightforward domino aza-Michael-inverse-electron-demand-hetero-Diels-Alder/retro-Diels-Alder reaction between primary and secondary propargylamine derivatives and 3-vinyl-1,2,4-triazines is developed highlighting not only the uniqueness of this dual-heterocyclic platform but also a novel and unprecedented path to polysubstituted tetrahydro-1,6-naphthyridine scaffolds.

Growth of Fullerene Fragments Using the Diels-Alder Cycloaddition Reaction: First Step towards a C60 Synthesis by Dimerization

Directory of Open Access Journals (Sweden)

Julio A. Alonso

2013-02-01

Full Text Available Density Functional Theory has been used to model the Diels-Alder reactions of the fullerene fragments triindenetriphenilene and pentacyclopentacorannulene with ethylene and 1,3-butadiene. The purpose is to prove the feasibility of using Diels-Alder cycloaddition reactions to grow fullerene fragments step by step, and to dimerize fullerene fragments, as a way to obtain C60. The dienophile character of the fullerene fragments is dominant, and the reaction of butadiene with pentacyclopentacorannulene is favored.

Nitropyrroles, Diels-Alder reactions assisted by microwave irradiation and solvent effect. An experimental and theoretical study

Science.gov (United States)

Mancini, Pedro M. E.; Kneeteman, María N.; Cainelli, Mauro; Ormachea, Carla M.; Domingo, Luis R.

2017-11-01

The behaviors of N-tosylnitropyrroles acting as electrophilic dienophiles in polar Diels-Alder reactions joint to different dienes of increeased nucleophilicity are analyzed. The reactions were developed under microwave irradiation using toluene or protic ionic liquids (PILs) as solvents and in free solvent conditions. In all the cases explored we observed good yields in short reaction times. For these reactions, the free solvent condition and the use of protic ionic liquids as solvents offer similar results. However, the free solvent conditions favor environmental sustainability. The role of PILs in these polar Diels-Alder reactions has been theoretically studied within the Molecular Electron Density Theory.

On a conjecture of Alley and Alder for fluids and Lorentz models

NARCIS (Netherlands)

Ernst, M.H.; Beijeren, H. van

1981-01-01

We discuss a conjecture of Alley and Alder predicting a relation between the four-point and the two-point velocity autocorrelation functions for fluids and Lorentz models at sufficiently long times. If the conjecture is correct a modified Burnett coefficient can be defined, which has a finite value,

Patterned-ground facilitates shrub expansion in Low Arctic tundra

International Nuclear Information System (INIS)

Frost, Gerald V; Epstein, Howard E; Walker, Donald A; Matyshak, Georgiy; Ermokhina, Ksenia

2013-01-01

Recent expansion of tall shrubs in Low Arctic tundra is widely seen as a response to climate warming, but shrubification is not occurring as a simple function of regional climate trends. We show that establishment of tall alder (Alnus) is strongly facilitated by small, widely distributed cryogenic disturbances associated with patterned-ground landscapes. We identified expanding and newly established shrub stands at two northwest Siberian sites and observed that virtually all new shrubs occurred on bare microsites (‘circles’) that were disturbed by frost-heave. Frost-heave associated with circles is a widespread, annual phenomenon that maintains mosaics of mineral seedbeds with warm soils and few competitors that are immediately available to shrubs during favorable climatic periods. Circle facilitation of alder recruitment also plausibly explains the development of shrublands in which alders are regularly spaced. We conclude that alder abundance and extent have increased rapidly in the northwest Siberian Low Arctic since at least the mid-20th century, despite a lack of summer warming in recent decades. Our results are consistent with findings in the North American Arctic which emphasize that the responsiveness of Low Arctic landscapes to climate change is largely determined by the frequency and extent of disturbance processes that create mineral-rich seedbeds favorable for tall shrub recruitment. Northwest Siberia has high potential for continued expansion of tall shrubs and concomitant changes to ecosystem function, due to the widespread distribution of patterned-ground landscapes. (letter)

Sequential aminodiene Diels-Alder approach to the ergoline skeleton.

Science.gov (United States)

Padwa, Albert; Bur, Scott K; Zhang, Hongjun

2005-08-19

Through a novel sequence of aminodiene Diels-Alder reactions, several substituted amidofurans were readily converted to tricyclic ketones in good yield. The formation of the tricyclic ketone system is the result of a ring opening and dehydration of a transient oxabicyclic adduct formed by an intramolecular Diels-Alder cycloaddition of an amidofuran with a cyclohexenone moiety tethered such that it participates in the cycloaddition as the 2pi component. A convenient way to construct the cyclohexenone is to make use of some aminodiene chemistry developed by Rawal. An angular carbomethoxy group is required in order to activate the olefin toward cycloaddition with Rawal's diene. The presence of this activating group not only prevents the isomerization of the advanced ergoline intermediate to a naphthalene but can also be leveraged for an oxidation to provide Uhle's ketone (13). The easily formed Kornfeld ketone analogue 25 was readily transformed into the corresponding triflate 41 by the action of triflic anhydride and a base. Oxidative addition of vinyl triflate 41 to Pd(0) and the ability of the resulting vinyl palladium species to undergo cross-coupling with terminal alkynes prompted us to devise an expeditious route to lysergic acid. Unfortunately, our inability to carry out a regioselective Heck reaction using vinyl triflate 41 and the methylene amino acrylate ester 48 thwarted the completion of the synthesis of lysergic acid.

Polar Diels-Alder reactions using electrophilic nitrobenzothiophenes. A combined experimental and DFT study

Science.gov (United States)

Della Rosa, Claudia D.; Mancini, Pedro M. E.; Kneeteman, Maria N.; Lopez Baena, Anna F.; Suligoy, Melisa A.; Domingo, Luis R.

2015-01-01

The reactions between 2- and 3-nitrobenzothiophenes with three dienes of different nucleophilicity, 1-methoxy-3-trimethylsilyloxy-1,3-butadiene, 1-trimethylsilyloxy-1,3-butadiene and isoprene developed in anhydrous benzene and alternative under microwave irradiation with molecular solvents or in free solvent conditions, respectively, for produce dibenzothiophenes permit to conclude that both nitroheterocycles act as electrophile with the cited dienes. In the cases of the dienes 1-methoxy-3-trimethylsilyloxy-1,3-butadiene and 1-trimethylsilyloxy-1,3-butadiene which posses major nucleophilicity the observed product is the normal cycloaddition one. However when the diene is isoprene the product with both electrophiles follow the hetero Diels-Alder way. These reactions are considered polar cycloaddition reactions and the yields are reasonables. Moreover the polar Diels-Alder reactions of nitrobenzothiophenes with electron rich dienes 1-trimethylsilyloxy-1,3-butadiene have been theoretically studied using DFT methods.

Postglacial vegetation history of Mitkof Island, Alexander Archipelago, southeastern Alaska

Science.gov (United States)

Ager, Thomas A.; Carrara, Paul E.; Smith, Jane L.; Anne, Victoria; Johnson, Joni

2010-03-01

An AMS radiocarbon-dated pollen record from a peat deposit on Mitkof Island, southeastern Alaska provides a vegetation history spanning ˜12,900 cal yr BP to the present. Late Wisconsin glaciers covered the entire island; deglaciation occurred > 15,400 cal yr BP. The earliest known vegetation to develop on the island (˜12,900 cal yr BP) was pine woodland ( Pinus contorta) with alder ( Alnus), sedges (Cyperaceae) and ferns (Polypodiaceae type). By ˜12,240 cal yr BP, Sitka spruce ( Picea sitchensis) began to colonize the island while pine woodland declined. By ˜11,200 cal yr BP, mountain hemlock ( Tsuga mertensiana) began to spread across the island. Sitka spruce-mountain hemlock forests dominated the lowland landscapes of the island until ˜10,180 cal yr BP, when western hemlock ( Tsuga heterophylla) began to colonize, and soon became the dominant tree species. Rising percentages of pine, sedge, and sphagnum after ˜7100 cal yr BP may reflect an expansion of peat bog habitats as regional climate began to shift to cooler, wetter conditions. A decline in alders at that time suggests that coastal forests had spread into the island's uplands, replacing large areas of alder thickets. Cedars ( Chamaecyparis nootkatensis, Thuja plicata) appeared on Mitkof Island during the late Holocene.

Theoretical study on the Diels-Alder reaction of bromo-substituted 2H-pyrane-2-ones and some substituent vinyls

Directory of Open Access Journals (Sweden)

Haghdadi Mina

2015-01-01

Full Text Available A DFT study of the reactivity, regio- and stereoselectivity of Diels-Alder reaction between 3-bromo, 5-bromo, and 3,5-dibromo-2(H-pyran-2-ones and some weakly activated and unactivated alkenes has been carried out using density functional theory (DFT. Four possible reaction channels, which are related to the formation of meta- and para- and endo- and exo-cycloadducts have been explored and characterized. The energy and natural bond orbital analysis shows that the meta-regioselectivity on the exo pathway is preferred and follows an asynchronous concerted mechanism with a polar nature in all Diels-Alder cycloadditions. Moreover, the activation free energies of Diels-Alder cycloadditions of 3,5-dibromo-2(H-pyran-2one are lower than 3- bromo-2(H-pyran-2one and 5-bromo-2(H-pyran-2one, which are in line with experimental observation. DFT-based reactivity indices clearly predict the regiochemistry of the isolated cycloadducts.

Don't camp beside the river: structure and dynamics of Andean alder (Alnus acuminata forests affected by river floods, northwestern Argentina No acampe junto al río: estructura y dinámica de bosques de aliso (Alnus acuminata del noroeste argentino afectados por crecientes de río

Directory of Open Access Journals (Sweden)

TOMÁS A EASDALE

2005-12-01

Full Text Available Alnus acuminata (Betulaceae is a pioneer tree that dominates mountain riparian forests throughout the eastern Andes. Early studies associated these forests with particular microclimatic conditions along river beds, but they were later linked to the periodical disturbance regime of mountain rivers. To understand the dynamics of these forests, we analysed tree age and spatial arrangement in two plots along Potrero river and another plot along La Horqueta river, Tucumán Province, north west Argentina. Through intensive tree coring and age reconstruction we identified similar-aged tree cohorts with maximum age ranges of eight years. Tree mapping and Moran's I spatial autocorrelation analysis showed that tree cohorts were spatially clumped, and provided further evidence that coetaneous patches of A. acuminata arise from massive regeneration following catastrophic flooding events. We tested the association between cohort initiation dates and regional maximum river discharge records by means of a randomization procedure and found weak evidence that establishment occurs after devastating floods, which eliminate previous vegetation and create bare sites suitable for A. acuminata regeneration. Dates of tree floodscars sampled along Potrero river precede by one year the most recent cohort initiation date and provide further support of this association. Although previous studies found a positive correlation between El Niño events and mean annual precipitation in northwestern Argentina, we did not detect an association between El Niño and annual maximum stream flow for rivers in Tucumán Province. Therefore, factors driving devastating floods and A. acuminata stand initiation require further studyEl aliso (Alnus acuminata, Betulaceae es un árbol pionero que domina bosques riparios de montaña en los Andes orientales. Estudios iniciales atribuyeron la presencia de estos bosques a las típicas condiciones microclimáticas de cauces de ríos, pero luego

Intramolecular and Transannular Diels-Alder Reactions

DEFF Research Database (Denmark)

Tanner, David Ackland; Ascic, Erhad

2014-01-01

Few reactions can compete with the Diels-Alder (DA) [4+2] cycloaddition for the rapid and efficient generation of molecular complexity. The DA reaction is atom-economic and stereospecific, as well as diastereo- and regioselective. The intramolecular version (IMDA) of the DA cycloaddition and its...... and dienophile, methods for acceleration of IMDA reactions (such as use of high pressure) and catalysis (using oxophilic or carbophilic metal complexes, Brønsted acids, and enzymes). The use of furans as diene components (IMDAF), intramolecular hetero-DA (IMHDA) and IMDA reactions with inverse electron demand...... are also covered. Applications of IMDA to asymmetric synthesis (from substrate control through to enantioselective catalysis, including organocatalysis) are presented, along with tandem sequences involving IMDA cycloaddition. A theme pervading the whole chapter is the use of IMDA reactions for the total...

Diels-Alder reactions onto fluorinated and hydrogenated graphene

Science.gov (United States)

Denis, Pablo A.

2017-09-01

We studied Diels-Alder (DA) reactions onto functionalized graphene. When fluorine, hydrogen or oxygen functional groups are present on one side of the sheet, the DA cycloadditions become significantly more exergonic when performed on the opposite side. Hydrogen is more effective than fluorine and oxygen to promote these cycloadditions. In contrast with the results obtained for perfect graphene, the functionalization with H, F or O turns the DA reactions exergonic, with ΔG°298 = -127.2 kcal/mol. The reaction barriers are expected to be considerably lowered with respect to perfect graphene because the functional groups significantly reduce the distortion energy.

Well-defined Polymethylene-Based Co/Terpolymers by Combining Anthracene/Maleimide Diels-Alder Reaction with Polyhomologation

KAUST Repository

Hadjichristidis, Nikolaos; Alkayal, Nazeeha

2015-01-01

A novel strategy towards well-defined polymethylene-based co/terpolymers, by combining anthracene/maleimide Diels-Alder reaction with polyhomologation, is presented. For the synthesis of diblock copolymers the following approach was applied: a

The Inverse Demand Oxa-Diels-Alder Reaction of Resorcinarenes: An Experimental and Theoretical Analysis of Regioselectivity and Diastereoselectivity.

Science.gov (United States)

Stefańska, Karolina; Jędrzejewska, Hanna; Wierzbicki, Michał; Szumna, Agnieszka; Iwanek, Waldemar

2016-07-15

The Diels-Alder reaction enables introduction of new functionalities onto the resorcinarene skeleton with simultaneous generation of new stereogenic centers and expansion of the internal cavity. We present highly regio- and diastereoselective inverse electron demand oxa-Diels-Alder reactions of resorcinarene ortho-quinone methide with benzofuran and indene, each generating 12 new stereogenic centers. The mechanism and reasons for regioselectivity and diastereoselectivity were analyzed using theoretical calculations (NBO charges, Fukui functions, transition state energies, and thermodynamic stability of the products). Enantiomers were separated, and their configurations were determined by comparison of experimental and theoretical electronic circular dichroism spectra.

Synthesis of isochromene-type scaffolds via single-flask Diels-Alder-[4 + 2]-annulation sequence of a silyl-substituted diene with menadione.

Science.gov (United States)

Lee, Jihoon; Panek, James S

2014-06-20

A sequential Diels-Alder reaction/silicon-directed [4 + 2]-annulation was developed to assemble hydroisochromene-type ring systems from menadione 2. In the first step, a Diels-Alder of the 1-silyl-substituted butadiene 1 with 2 furnished an intermediate cyclic allylsilane. Subsequently, TMSOTf promoted a [4 + 2]-annulation through trapping of an oxonium, generated by condensation between an aldehyde and the TBS protected alcohol resulted in the formation of a cis-fused hydroisochromene 13.

Origin of Exo/Endo Selectivity in the Intramolecular Diels-Alder Reaction

International Nuclear Information System (INIS)

Yan, Shihai; Ryu, Do Hyun; Lee, Jin Yong

2010-01-01

The stereoselectivity of the intramolecular Diels-Alder reactions of 1 and its derivatives were investigated by ab initio calculations. The stereoselectivity mainly originates from the steric repulsion and the orbital interactions. The additional s-cis and s-trans conformations by introducing the carbonyl group at the neighbor of diene or dienophile may change the stereoselectivity, hence this kind of substitution can be utilized for stereoselective asymmetric synthesis

Effects of the Hydrophobicity of the Reactants on Diels-Alder Reactions in Water

NARCIS (Netherlands)

Meijer, Ale; Otto, Sijbren; Engberts, Jan B.F.N.

1998-01-01

To assess the importance of the hydrophobicity of different parts of diene and dienophile on the aqueous acceleration of Diels-Alder reactions, second-order rate constants have been determined for the reactions of cyclopentadiene (1), 2,3-dimethyl-1,3-butadiene (4), and 1,3-cyclohexadiene (6) with

Stereo-controlled synthesis of polyheterocycles via the diene-transmissive hetero-Diels-Alder reaction of β,γ-unsaturated α-keto esters.

Science.gov (United States)

Otani, Takashi; Tamai, Yumiko; Seki, Kazunori; Kikuchi, Tomohiro; Miyazawa, Taiichiro; Saito, Takao

2015-06-07

We describe the stereoselective synthesis of polyring-fused heterocyclic compounds based on diene-transmissive hetero-Diels-Alder reactions utilizing β,γ-unsaturated α-keto esters. This protocol involves the initial endo- or exo-selective Diels-Alder (DA) reactions with electron-rich dienophiles, methylenation of the ester carbonyl groups with the Tebbe reagent, and a stereoselective second DA reaction with electron-deficient dienophiles. The use of enantioselective DA reactions in the initial reaction enables access to chiral polyring-fused heterocyclic compounds with multiple chiral centres.

Domino Wittig Diels-Alder reaction: An expeditious entry into the AB ring system of furanosesquiterpenes

Digital Repository Service at National Institute of Oceanography (India)

Patre, R.E.; Gawas, S.; Sen, S.; Parameswaran, P.S.; Tilve, S.G.

A domino Wittig Diels - Alder reaction has been employed in delineating a short and flexible synthetic stratagem for ready access to the AB ring system and the tricyclic framework of furanosesquiterpenes, such as the bioactive natural products...

The Preparation and Properties of Thermo-reversibly Cross-linked Rubber Via Diels-Alder Chemistry

NARCIS (Netherlands)

Polgar, Lorenzo Massimo; van Duin, Martin; Picchioni, Francesco

2016-01-01

A method for using Diels Alder thermo-reversible chemistry as cross-linking tool for rubber products is demonstrated. In this work, a commercial ethylene-propylene rubber, grafted with maleic anhydride, is thermo-reversibly cross-linked in two steps. The pending anhydride moieties are first modified

Fungi occurring on forests injured by air pollutants in the Upper Silesia and Cracow industrial regions. Pt. 10. Mycoflora of dying young trees of Alnus incana

Energy Technology Data Exchange (ETDEWEB)

Domanski, S.; Kowalski, T.

1987-01-01

The results of a 10-year study on the mortality of Alnus incana in the Upper Silesia industrial region (Poland) are presented in this paper. Fungi which infected the trees at different stages of the disease were identified. The most common were: Cryptosphora suffusa, Hypoxylon fuscum, Peniophora cinerea, P. erikssonii, Pezicula cinnamomea, Tymipanis alnea, and Valsa diatrypa.

Red Alder-Conifer Stands in Alaska: An Example of Mixed Species Management to Enhance Structural and Biological Complexity

Directory of Open Access Journals (Sweden)

Robert L. Deal

2017-04-01

Full Text Available There is worldwide interest in managing forests to improve biodiversity, enhance ecosystem services and assure long-term sustainability of forest resources. An increasingly important goal of forest management is to increase stand diversity and improve wildlife and aquatic habitat. Well-planned silvicultural systems containing a mixture of broadleaf-conifer species have potential to enhance stand diversity and provide other ecosystem services earlier than typical even-aged conifer plantations. Here, we use the example of mixed Sitka spruce/western hemlock and red alder in young, managed stands in southeast Alaska to achieve these goals. We briefly describe the silvics of Sitka spruce, western hemlock and red alder plantations as pure conifer stands or pure broadleaf stands. Then, we synthesize studies of mixed red alder-Sitka spruce/western hemlock stands in southeast Alaska and present their potential for improving stand structural complexity, biodiversity and other ecosystem services over pure conifer forests. Finally, we discuss some of the opportunities and potential tradeoffs for managing mixed broadleaf-conifer stands for providing a number of natural resources and the influence of these broadleaf-conifer forests on ecosystem linkages and processes.

Hydrogen-Bonding Catalysis of Tetraalkylammonium Salts in an Aza-Diels-Alder Reaction.

Science.gov (United States)

Kumatabara, Yusuke; Kaneko, Shiho; Nakata, Satoshi; Shirakawa, Seiji; Maruoka, Keiji

2016-08-05

A piperidine-derived tetraalkylammonium salt with a non-coordinating counteranion worked as an effective hydrogen-bonding catalyst in an aza-Diels-Alder reaction of imines and a Danishefsky diene. The hydrogen-bonding interaction between the ammonium salt and an imine was observed as part of a (1) H NMR titration study. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A computational study of the Diels-Alder reactions between 2,3-dibromo-1,3-butadiene and maleic anhydride

Science.gov (United States)

Rivero, Uxía; Meuwly, Markus; Willitsch, Stefan

2017-09-01

The neutral and cationic Diels-Alder-type reactions between 2,3-dibromo-1,3-butadiene and maleic anhydride have been computationally explored as the first step of a combined experimental and theoretical study. Density functional theory calculations show that the neutral reaction is concerted while the cationic reaction can be either concerted or stepwise. Further isomerizations of the Diels-Alder products have been studied in order to predict possible fragmentation pathways in gas-phase experiments. Rice-Ramsperger-Kassel-Marcus (RRKM) calculations suggest that under single-collision experimental conditions the neutral product may reform the reactants and the cationic product will most likely eliminate CO2.

Sara Wasson and Emily Alder, Gothic Science Fiction 1980-2010

OpenAIRE

Beaulé, Sophie

2014-01-01

With their collection of essays Gothic Science Fiction 1980-2010, Sara Wasson and Emily Alder illustrate the richness of gothic tropes in contemporary forms, from novels and movies to card games. More than cliché, melodrama, or gore, the “gothick” (to borrow Adam Roberts’s term, xi) allows for the hybridity in contemporary production, especially in science fiction, that the collected articles examine. The book is divided into three parts, “Redefining Genres”, “Biopower and Capital”, and “Gend...

Unconventional exo selectivity in thermal normal-electron-demand Diels-Alder reactions

Science.gov (United States)

Ho, Guo-Ming; Huang, Ci-Jhang; Li, Elise Yu-Tzu; Hsu, Sheng-Kai; Wu, Ti; Zulueta, Medel Manuel L.; Wu, Kevin Binchia; Hung, Shang-Cheng

2016-10-01

The Diels-Alder reaction is a useful tool for generating functionalized chiral molecules through the concerted cycloaddition of dienes and dienophiles leading to six-membered rings. Traditionally, the selective predictions of the products rely heavily on consideration of the secondary orbital interactions that stabilize the endo pathway. However, there remain some basic examples defying this notion and produce the exo-isomer as major product. Here we systematically evaluated of the structural features driving exo selectivity in thermal normal-electron-demand Diels-Alder reactions. Substitution at the Cβ position and the size and electronegativity of the electron-withdrawing group of the dienophile are contributing factors. Experimental and computational studies both point toward the steric and electrostatic forces between the substituents in both the diene and the dienophile that increase the likelihood of the exo pathway. For these substrates, the dominance of the endo pathway is reduced by transition state distortions and poor structural alignments of the reacting partners. We also noted the tilt of the dienophile with respect to the diene causing steric strain on the functionalities at the more advanced bond forming carbon-carbon position of the endo transition state. Insights into such factors may benefit synthetic planning and asserting control over this important named reaction.

Effects of rooting and tree growth of selected woodland species on cap integrity in a mineral capped landfill site.

Science.gov (United States)

Hutchings, T R; Moffat, A J; Kemp, R A

2001-06-01

The above and below ground growth of three tree species (Alnus glutinosa, Pinus nigra var. maritima and Acer pseudoplatanus) was studied on a containment landfill site at Waterford, Hertfordshire, UK. Tree root architecture was studied using soil inspection pits excavated next to 12 trees of each species and mapped in detail. Tree height was related to soil thickness over the compacted mineral cap. No roots entered the cap where soil thickness was 1.3 m, but a few roots, especially of alder, were observed within it when the soil cover was 1.0 m or less. Micromorphological analysis of undisturbed samples of the mineral cap suggested that roots exploited weaknesses in the cap rather than actively causing penetration into it. Alder roots were more tolerant of anaerobic conditions within the cap than the other species examined. The results confirm that mineral caps should be covered by 1.5 m of soil or soil-forming material if tree establishment is intended over a restored landfill site, unless protected by other parts of a composite capping system.

Grazing preference and utilization of soil fungi by Folsomia candida (Collembola)

Science.gov (United States)

Hedenec, Petr; Frouz, Jan

2016-04-01

Soil fungi are important food resources for soil fauna. Here we ask whether the collembolan Folsomia candida shows selectivity in grazing between four saprophytic fungi (Penicillium chrysogenum, Penicillium expansum, Absidia glauca, and Cladosporium herbarum), whether grazing preference corresponds to effects on collembolan reproduction, and whether the effects of fungi on grazing and reproduction depends on the fungal substrate, which included three kinds of litter (Alnus glutinosa, Salix caprea, and Quercus robur) and one kind of agar (yeast extract). On agar, Cladosporium herbarum and Absidia glauca were the most preferred fungi and supported the highest collembolan reproduction. On fungal-colonized litter, grazing preference was more affected by litter type than by fungal species whereas collembolan reproduction was affected by both litter type and fungal species. On fungal-colonized litter, the litter type that was most preferred for grazing did not support the highest reproduction, i.e., there was an inconsistency between food preference and suitability. Alder and willow were preferred over oak for grazing, but alder supported the least reproduction.

phenylalanine and l-tyrosine as chiral micellar media for the cat

African Journals Online (AJOL)

potential chiral micellar catalysts for the Diels-Alder reaction between methyl acrylate and .... hydrophobic effects, electrostatic interactions and the accompanying medium effects. In the case .... liquids as effective organocatalysts for Diels-Alder reaction. Green Chem. 2014, 16 .... Colloids and Surfaces A: Physicochem.

Specific acid catalysis and Lewis acid catalysis of Diels–Alder reactions in aqueous media

NARCIS (Netherlands)

Mubofu, Egid B.; Engberts, Jan B.F.N.

2004-01-01

A comparative study of specific acid catalysis and Lewis acid catalysis of Diels–Alder reactions between dienophiles (1, 4 and 6) and cyclopentadiene (2) in water and mixed aqueous media is reported. The reactions were performed in water with copper(II) nitrate as the Lewis acid catalyst whereas

Specific acid catalysis and Lewis acid catalysis of Diels-Alder reactions in aqueous media

NARCIS (Netherlands)

Mubofu, E.B.; Engberts, J.B.F.N.

A comparative study of specific acid catalysis and Lewis acid catalysis of Diells-Alder reactions between dienophiles (1, 4 and 6) and cyclopentadiene (2) in water and mixed aqueous media is reported. The reactions were performed in water with copper(II) nitrate as the Lewis acid catalyst whereas

Kinetic and thermodynamic measurements for the facile property prediction of diels-alder-conjugated material behavior

Czech Academy of Sciences Publication Activity Database

Koehler, K. C.; Ďuračková, Andrea; Kloxin, C. J.; Bowman, C. N.

2012-01-01

Roč. 58, č. 11 (2012), s. 3545-3552 ISSN 0001-1541 Institutional research plan: CEZ:AV0Z40500505 Keywords : Diels - Alder reaction s * self-healing polymer networks * thermoreversible reaction s Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.493, year: 2012

Revisiting the stability of endo/exo Diels-Alder adducts between cyclopentadiene and 1,4-benzoquinone

International Nuclear Information System (INIS)

Tormena, Claudio F.; Lacerda Junior, Valdemar; Oliveira, Kleber T. de

2010-01-01

In this work it is presented a detailed theoretical analysis of the relative stability of endo/exo Diels-Alder adducts formed by the reaction between cyclopentadiene (1) and 1,4-benzoquinone (2). The intrinsic reaction coordinate (IRC) showed the existence of only one transition state for the reaction studied, for both endo 3 and exo 4 adducts. The energies of both adducts were obtained at high level of theory (CBS-Q) confirming that the endo adduct is more stable than exo, which is in the opposite way to the observed in reactions that usually follow Alder's rule. An electronic structure analysis was performed through NBO methodology, indicating that the attractive delocalization interaction predominates over the steric repulsive interaction in the endo adducts. In summary, for the studied cycloaddition reaction the endo adduct is the thermodynamic and kinetic product, which can be also confirmed by experimental data mentioned in this work. (author)

Kinetic study of the Diels-Alder reaction of Li⁺@C₆₀ with cyclohexadiene: greatly increased reaction rate by encapsulated Li⁺.

Science.gov (United States)

Ueno, Hiroshi; Kawakami, Hiroki; Nakagawa, Koji; Okada, Hiroshi; Ikuma, Naohiko; Aoyagi, Shinobu; Kokubo, Ken; Matsuo, Yutaka; Oshima, Takumi

2014-08-06

We studied the kinetics of the Diels-Alder reaction of Li(+)-encapsulated [60]fullerene with 1,3-cyclohexadiene and characterized the obtained product, [Li(+)@C60(C6H8)](PF6(-)). Compared with empty C60, Li(+)@C60 reacted 2400-fold faster at 303 K, a rate enhancement that corresponds to lowering the activation energy by 24.2 kJ mol(-1). The enhanced Diels-Alder reaction rate was well explained by DFT calculation at the M06-2X/6-31G(d) level of theory considering the reactant complex with dispersion corrections. The calculated activation energies for empty C60 and Li(+)@C60 (65.2 and 43.6 kJ mol(-1), respectively) agreed fairly well with the experimentally obtained values (67.4 and 44.0 kJ mol(-1), respectively). According to the calculation, the lowering of the transition state energy by Li(+) encapsulation was associated with stabilization of the reactant complex (by 14.1 kJ mol(-1)) and the [4 + 2] product (by 5.9 kJ mol(-1)) through favorable frontier molecular orbital interactions. The encapsulated Li(+) ion catalyzed the Diels-Alder reaction by lowering the LUMO of Li(+)@C60. This is the first detailed report on the kinetics of a Diels-Alder reaction catalyzed by an encapsulated Lewis acid catalyst rather than one coordinated to a heteroatom in the dienophile.

A Computational Experiment of the Endo versus Exo Preference in a Diels-Alder Reaction

Science.gov (United States)

Rowley, Christopher N.; Woo, Tom K.

2009-01-01

We have developed and tested a computational laboratory that investigates an endo versus exo Diels-Alder cycloaddition. This laboratory employed density functional theory (DFT) calculations to study the cycloaddition of N-phenylmaleimide to furan. The endo and exo stereoisomers of the product were distinguished by building the two isomers in a…

High-level Computational Study of the Site-, Facial- and Stereoselectivities for the Diels-Alder Reaction Between o-Benzoquinone and Norbornadiene

Directory of Open Access Journals (Sweden)

Ronald N. Warrener

2000-12-01

Full Text Available Ab initio and DFT quantum chemical calculations have been applied to a study of the Diels-Alder reaction of o-benzoquinone as diene and norbornadiene as dienophile. Transition states for the different reactions are located and activation energies estimated. The prefered exo-π-facial selectivity and exo,endo-stereoselectivity exhibited in this cycloaddition are readily predicted using RHF/3-21G or higher levels of calculations. Differences between experimentally observed results and calculations may be explained by the postulation of a second, nonconcerted biradical mechanism leading to formation of hetero Diels-Alder products.

The unexpected product of Diels-Alder reaction between "indanocyclon" and maleimide

Science.gov (United States)

Dobrowolski, Michał A.; Roszkowski, Piotr; Struga, Marta; Szulczyk, Daniel

2017-02-01

A heterocyclic compound commonly known as "indanocyclon" undergoes an unexpected Diels-Alder addition with maleimide. The resulting product has been isolated and characterized in order to get an information about its structure and possible mechanism of the reaction. Extensive comparison of single crystal properties of 3-(2,8-dioxo-1,3-diphenyl-2,8-dihydrocyclopenta[a]inden-8a(1H)-yl)pyrrolidine-2,5-dione and favorable product of the reaction has been also performed.

New L-Serine Derivative Ligands as Cocatalysts for Diels-Alder Reaction

Science.gov (United States)

Sousa, Carlos A. D.; Rodríguez-Borges, José E.; Freire, Cristina

2013-01-01

New L-serine derivative ligands were prepared and tested as cocatalyst in the Diels-Alder reactions between cyclopentadiene (CPD) and methyl acrylate, in the presence of several Lewis acids. The catalytic potential of the in situ formed complexes was evaluated based on the reaction yield. Bidentate serine ligands showed good ability to coordinate medium strength Lewis acids, thus boosting their catalytic activity. The synthesis of the L-serine ligands proved to be highly efficient and straightforward. PMID:24383009

Diels-Alder cyclo-addition as an efficient tool for linking π-donors onto fullerene C60

International Nuclear Information System (INIS)

Hudhomme, P.

2006-01-01

Diels-Alder reaction of endo-cyclic, acyclic 1,3-dienes or (hetero) o-quinodimethanes with the dienophilic fullerene C 60 is presented as an efficient tool for linking electro-active units giving rise to systems where both the donor and C 60 partners take up well defined volumes and orientations with respect to one another. While porphyrin is the most frequently used electron donor in artificial photosynthetic models, C 60 -based tetrathiafulvalene (TTF) or p-conjugated oligomer adducts remain interesting candidates for the preparation of photovoltaic devices. In this account, we focus on the use of the Diels-Alder cyclo-addition and its use in the synthesis of TTF-C 60 dyads, (TTF) n -C 60 polyads and C 60 -TTF-C 60 dumbbells as part of ongoing research into materials which display efficient photo-induced electron transfer. (author)

Exploring Reaction Mechanism on Generalized Force Modified Potential Energy Surfaces (G-FMPES) for Diels-Alder Reaction

Science.gov (United States)

Jha, Sanjiv; Brown, Katie; Subramanian, Gopinath

We apply a recent formulation for searching minimum energy reaction path (MERP) and saddle point to atomic systems subjected to an external force. We demonstrate the effect of a loading modality resembling hydrostatic pressure on the trans to cis conformational change of 1,3-butadiene, and the simplest Diels-Alder reaction between ethylene and 1,3-butadiene. The calculated MERP and saddle points on the generalized force modified potential energy surface (G-FMPES) are compared with the corresponding quantities on an unmodified potential energy surface. Our study is performed using electronic structure calculations at the HF/6-31G** level as implemented in the AIMS-MOLPRO code. Our calculations suggest that the added compressive pressure lowers the energy of cis butadiene. The activation energy barrier for the concerted Diels-Alder reaction is found to decrease progressively with increasing compressive pressure.

A Kinetic Study of the Diels-Alder Reaction. An Experiment Illustrating Simple Second-Order Reaction Kinetics.

Science.gov (United States)

Silvestri, Michael G.; Dills, Charles E.

1989-01-01

Describes an organic chemistry experiment for teaching the basic concepts of chemical kinetics. Provides background information about first- and second-order reactions, experimental procedures of the Diels-Alder reaction between cyclopentadiene and dimethyl fumarate, and the experimental results. (YP)

Expanding the scope of cyclopropene reporters for the detection of metabolically engineered glycoproteins by Diels–Alder reactions

Directory of Open Access Journals (Sweden)

Anne-Katrin Späte

2014-09-01

Full Text Available Monitoring glycoconjugates has been tremendously facilitated by the development of metabolic oligosaccharide engineering. Recently, the inverse-electron-demand Diels–Alder reaction between methylcyclopropene tags and tetrazines has become a popular ligation reaction due to the small size and high reactivity of cyclopropene tags. Attaching the cyclopropene tag to mannosamine via a carbamate linkage has made the reaction even more efficient. Here, we expand the application of cyclopropene tags to N-acylgalactosamine and N-acylglucosamine derivatives enabling the visualization of mucin-type O-glycoproteins and O-GlcNAcylated proteins through Diels–Alder chemistry. Whereas the previously reported cyclopropene-labeled N-acylmannosamine derivative leads to significantly higher fluorescence staining of cell-surface glycoconjugates, the glucosamine derivative gave higher labeling efficiency with protein preparations containing also intracellular proteins.

Revisiting the stability of endo/exo Diels-Alder adducts between cyclopentadiene and 1,4-benzoquinone

Energy Technology Data Exchange (ETDEWEB)

Tormena, Claudio F. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Inst. de Quimica. Dept. de Quimica Organica; Lacerda Junior, Valdemar [Universidade Federal do Espirito Santo (UFES), Vitoria, ES (Brazil). Centro de Ciencias Exatas. Dept. de Quimica; Oliveira, Kleber T. de [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil). Centro de Ciencias Naturais e Humanas

2010-07-01

In this work it is presented a detailed theoretical analysis of the relative stability of endo/exo Diels-Alder adducts formed by the reaction between cyclopentadiene (1) and 1,4-benzoquinone (2). The intrinsic reaction coordinate (IRC) showed the existence of only one transition state for the reaction studied, for both endo 3 and exo 4 adducts. The energies of both adducts were obtained at high level of theory (CBS-Q) confirming that the endo adduct is more stable than exo, which is in the opposite way to the observed in reactions that usually follow Alder's rule. An electronic structure analysis was performed through NBO methodology, indicating that the attractive delocalization interaction predominates over the steric repulsive interaction in the endo adducts. In summary, for the studied cycloaddition reaction the endo adduct is the thermodynamic and kinetic product, which can be also confirmed by experimental data mentioned in this work. (author)

Naphthalene Diels-Alder in a self-assembled molecular flask.

Science.gov (United States)

Murase, Takashi; Horiuchi, Shinnosuke; Fujita, Makoto

2010-03-10

Despite its inertness toward pericyclic reactions under common conditions, naphthalenes readily undergo Diels-Alder reactions when coencapsulated with a suitable dienophile within the cavity of a self-assembled host. Localization of the reactant pair significantly reduces the entropic cost of the reaction, and preorganization within the host cavity controls both the regio- and stereoselectivity of the reaction: electronically disfavored exo adducts were obtained, and with substituted naphthalenes, the reaction takes place on the less electron-rich, unsubstituted ring. Our findings highlight the fact that judicious tuning of substrate size and shape within molecular flasks can unveil new and unusual reactivities for otherwise unreactive molecules.

Theory of Brownian motion with the Alder-Wainwright effect

International Nuclear Information System (INIS)

Okabe, Y.

1986-01-01

The Stokes-Boussinesq-Langevin equation, which describes the time evolution of Brownian motion with the Alder-Wainwright effect, can be treated in the framework of the theory of KMO-Langevin equations which describe the time evolution of a real, stationary Gaussian process with T-positivity (reflection positivity) originating in axiomatic quantum field theory. After proving the fluctuation-dissipation theorems for KMO-Langevin equations, the authors obtain an explicit formula for the deviation from the classical Einstein relation that occurs in the Stokes-Boussinesq-Langevin equation with a white noise as its random force. The authors interested in whether or not it can be measured experimentally

Diels-Alder Reaction of Isobenzofurans/Cyclopentadienones with Tetrathiafulvalene: Preparation of Naphthalene, Fluoranthene, and Fluorenone Derivatives.

Science.gov (United States)

Karunakaran, Jayachandran; Mohanakrishnan, Arasambattu K

2018-02-16

Diels-Alder reaction of 1,3-diarylbenzo[c]furan/cyclopentadienone with TTF followed by triflic acid mediated cleavage of the resulting adducts led to the formation of the respective 1,4-diaryl substituted naphthalenes, fluoranthenes, and fluorenones. The photophysical properties of representative diaryl-substituted hydrocarbons are also reported.

Retro-Diels-Alder reaction in aqueous solution : Toward a better understanding of organic reactivity in water

NARCIS (Netherlands)

Wijnen, J.W.; Engberts, Jan B.F.N.

1997-01-01

The retro-Diels-Alder (RDA) reaction of anthracenedione 1a proceeds considerably faster in aqueous solutions than in organic solvents. Addition of organic solvents to water retards the reaction, whereas glucose induces a modest acceleration. SDS micelles induce a considerable retardation, but even

Asymmetric Brønsted acid-catalyzed aza-Diels–Alder reaction of cyclic C-acylimines with cyclopentadiene

Directory of Open Access Journals (Sweden)

Magnus Rueping

2012-10-01

Full Text Available A new chiral Brønsted acid-catalyzed aza-Diels–Alder reaction of cyclic C-acylimines with cyclopentadiene has been developed. The reaction provides optically active aza-tetracycles in good yields with high diastereo- and enantioselectivities under mild reaction conditions.

Nitrogen fixation and growth response of Alnus Rubra following fertiliztion with urea or biosolids Fixação de nitrogênio e crescimento de Alnus Rubra fertilização com uréia ou biosólidos

Directory of Open Access Journals (Sweden)

Linda S. Gaulke

2006-08-01

Full Text Available Nitrogen fertilization of forests using biosolids offers a potentially environmentally friendly means to accelerate tree growth. This field study was designed to analyze the effects of nitrogen fertilization on the symbiotic, nitrogen (N-fixing relationship between Alnus rubra Bong. (red alder and Frankia. Anaerobically digested, class B biosolids and synthetic urea (46% N were applied at rates of 140, 280 and 560 kg ha-1 available N to a well-drained, sandy, glacial outwash soil in the Indianola series (mixed, mesic Dystric Xeropsamments. Plots were planted with A. rubra seedlings. At the end of each of two growing seasons trees were harvested and analyzed for the rate of N fixation (as acetylene reduction activity, biomass and foliar N. At year 1, there was no N fixation for trees grown with urea amendments, but control (17 µmol C2H4 g-1 hr-1 and biosolids (26-45 µmol C2H4 g-1 hr-1 trees were fixing N. At the end of year 2, all trees in all treatments were fixing N (7 µmol C2H4 g-1 hr-1, 4-16 µmol C2H4 g-1 hr-1, and 20-29 µmol C2H4 g-1 hr-1 for control, urea and biosolids respectively. Trees grown with biosolids amendments were larger overall (year 1 shoot biomass 10 g, 5 g, and 23 g for control, urea, and biosolids respectively, year 2 shoot biomass 50 g, 51 g, and 190 g for control, urea, and biosolids respectively with higher concentrations of foliar N for both years of the study (year 1 foliar N 26 g kg-1, 27 g kg-1, and 40 g kg-1 for control, urea, and biosolids respectively, year 2 foliar N 17 g kg-1, 19 g kg-1, and 23 g kg-1 for control, urea, and biosolids respectively. Trees grown with urea amendments appeared to use the urea N over Frankia supplied N, whereas the biosolids trees appeared to be able to use both N in biosolids and N from Frankia. The results from this study indicated that the greater growth of A. rubra may have been responsible for the observed higher N demand. Biosolids may have supplied other nutrients to the

Pathogenicity of the bioherbicide fungus chondrostereum purpureum to some trees and shrubs of southern Vancouver Island. FRDA report No. 246

Energy Technology Data Exchange (ETDEWEB)

Wall, R.E.

1996-11-01

Chondrostereum purpureum is a common stem-invading fungus of trees and shrubs. The fungus has attracted interest as a bioherbicide, but a better understanding of its biology is required. This study was undertaken to determine the range of virulence of isolates of C. purpureum from a given region on major hardwood species in British Columbia. The investigators inoculated wounds of stems of standing red alder (Alnus rubra) and bigleaf maple (Acer macrophyllum) saplings with 11 isolates of the fungus and measured the resulting stem cankers as an index of virulence. They also inoculated eight hardwood and shrub species with two isolates to demonstrate the range of susceptibility of species to the fungus, as well as the intraspecific variation.

Biological nitrogen fixation in relation to energy forest production. Progress report, 1978-1980

Energy Technology Data Exchange (ETDEWEB)

Clarholm, M; Granhall, U

1981-01-01

Different pasture legumes, Alnus incana and Myrica gale have been tested in pot experiments and field trials with respect to their use as biological N-fertilizers in relation to energy forest production. So far experiments have been mainly concerned with their establishemnts as on intercrop with Galix at a mire site with ombrotrophic peat and in two clayish arable soils. Laboratory experiments have been made to determine optimal conditions for growth and nitrogen fixation of wild and Alaska lupines in relation to varous soil amendments in the form of lime, ash, NPKMo, and Fe. A pilot experiment of the terrelations between willows and grey alder growing together in peat has been started at Uppsala.

Stepwise or concerted? DFT study on the mechanism of ionic Diels-Alder reaction of chromanes

Directory of Open Access Journals (Sweden)

Haghdadi Mina

2016-01-01

Full Text Available The stepwise and concerted Ionic Diels-Alder reaction between phenyl (pyridin-2-ylmethylene oxonium and styrene derivatives are explored using theoretical method. The results support using computational method via persistent intermediates. The DFT method was essential to reproduce a reasonable potential energy surface for these challenging systems.

Asymmetric NHC-catalyzed aza-Diels-Alder reactions: Highly enantioselective route to α-amino acid derivatives and DFT calculations

KAUST Repository

Yang, Limin; Wang, Fei; Lee, Richmond; Lv, Yunbo; Huang, Kuo-Wei; Zhong, Guofu

2014-01-01

A facile N-heterocyclic carbene catalytic enantioselective aza-Diels-Alder reaction of oxodiazenes with α-chloroaldehydes as dienophile precursors is reported, with excellent enantioselectivity (ee > 99%) and excellent yield (up to 93%). DFT study

Cascade olefin isomerization/intramolecular Diels-Alder reaction catalyzed by N-heterocyclic carbenes.

Science.gov (United States)

Kowalczyk, Marcin; Lupton, David W

2014-05-19

The addition of an N-heterocyclic carbene to the carbonyl group of an α,β,γ,δ-unsaturated enol ester affords a hemiacetal azolium intermediate that enables a cascade olefin isomerization/Diels-Alder reaction, for which mechanistic studies implicate Lewis base catalysis. Preliminary studies into the utility of the products have been undertaken with reductive and oxidative cleavage, giving materials for potential use in complex-target synthesis. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Intramolecular anionic diels-alder reactions of 1-aryl-4-oxahepta-1,6-diyne systems in DMSO.

Science.gov (United States)

Kudoh, Takayuki; Mori, Tomoko; Shirahama, Mitsuhito; Yamada, Masashi; Ishikawa, Teruhiko; Saito, Seiki; Kobayashi, Hisayoshi

2007-04-25

Base-promoted cycloaddition reactions of 1-aryl- or 1-aryl-7-substituted-4-oxahepta-1,6-diyne systems in DMSO have proven to involve an anionic intramolecular Diels-Alder process taking place even at room temperature in spite of the reaction suffering from temporary disruption of aromaticity. Although initially formed alpha-arylallenide anion can be protonated by DMSO, it can be back to the allenide anion probably because of a small acidity difference between alpha-arylallene and DMSO. The alpha-arylallenide anion in combination with the alpha-aryl substituent can constitute an anionic diene structure that undergoes the intramolecular Diels-Alder reaction involving the C(6)-yne part, a very fast process probably because of the increased HOMO-1 level of the anionic diene, as shown by DFT calculations. Diversified substituted naphthalenes, benzofurans, phenanthrenes, and quinolines, including biaryl architectures, are available from 4-oxahepta-1,6-diynes in a highly expeditious way.

An interpenetrating HA/G/CS biomimic hydrogel via Diels-Alder click chemistry for cartilage tissue engineering.

Science.gov (United States)

Yu, Feng; Cao, Xiaodong; Zeng, Lei; Zhang, Qing; Chen, Xiaofeng

2013-08-14

In order to mimic the natural cartilage extracellular matrix, a novel biological degradable interpenetrating network hydrogel was synthesized from the gelatin (G), hyaluronic acid (HA) and chondroitin sulfate (CS) by Diels-Alder "click" chemistry. HA was modified with furylamine and G was modified with furancarboxylic acid respectively. (1)H NMR spectra and elemental analysis showed that the substitution degrees of HA-furan and G-furan were 71.5% and 44.5%. Then the hydrogels were finally synthesized by cross-linking furan-modified HA and G derivatives with dimaleimide poly(ethylene glycol) (MAL-PEG-MAL). The mechanical and degradation properties of the hydrogels could be tuned simply through varying the molar ratio between furan and maleimide. Rheological, mechanical and degradation studies demonstrated that the Diels-Alder "click" chemistry is an efficient method for preparing high performance biological interpenetrating hydrogels. This biomimic hydrogel with improved mechanical properties could have great potential applications in cartilage tissue engineering. Copyright © 2013 Elsevier Ltd. All rights reserved.

A facile avenue to conductive polymer brushes via cyclopentadiene-maleimide Diels-Alder ligation

Czech Academy of Sciences Publication Activity Database

Yameen, B.; Rodriguez-Emmenegger, C.; Preuss, C. M.; Pop-Georgievski, Ognen; Verveniotis, Elisseos; Trouillet, V.; Rezek, Bohuslav; Barner-Kowollik, C.

2013-01-01

Roč. 49, č. 77 (2013), s. 8623-8625 ISSN 1359-7345 R&D Projects: GA ČR GBP205/12/G118; GA ČR GAP108/11/1857; GA ČR(CZ) GBP108/12/G108 Institutional support: RVO:61389013 ; RVO:68378271 Keywords : conductive poly(3-hexylthiophen) brushes * Diels-Alder ligation * Kelvin Probe Force Microscopy (KFM) Subject RIV: CD - Macromolecular Chemistry Impact factor: 6.718, year: 2013

One-step versus two-step mechanism of Diels-Alder reaction of 1-chloro-1-nitroethene with cyclopentadiene and furan.

Science.gov (United States)

Jasiński, Radomir

2017-08-01

DFT computational study shows that Diels-Alder (DA) reactions of 1-chloro-1-nitroethene with cyclopentadiene and furan have polar nature. However, their mechanism is substantially different. In particular, 1-chloro-1-nitroethene react with cyclopentadiene according to one-step mechanism. In the same time, more favourable channel associated with the P-DA reaction between furan and 1-chloro-1-nitroethene is a domino process, that comprises an initial hetero-Diels-Alder reaction yielding a [2+4] cycloadduct, which experiences a subsequent [3,3] sigmatropic shift to yield the expected formal [4+2] cycloadduct. This is a consequence of more polar nature of reaction, due to higher nucleophilicity of furan in comparison to cyclopentadiene. Copyright © 2017 Elsevier Inc. All rights reserved.

Hetero-Diels–Alder reactions of hetaryl and aryl thioketones with acetylenic dienophiles

Directory of Open Access Journals (Sweden)

Grzegorz Mlostoń

2015-04-01

Full Text Available Selected hetaryl and aryl thioketones react with acetylenecarboxylates under thermal conditions in the presence of LiClO4 or, alternatively, under high-pressure conditions (5 kbar at room temperature yielding thiopyran derivatives. The hetero-Diels–Alder reaction occurs in a chemo- and regioselective manner. The initially formed [4 + 2] cycloadducts rearrange via a 1,3-hydrogen shift sequence to give the final products. The latter were smoothly oxidized by treatment with mCPBA to the corresponding sulfones.

Procesos morfológicos en la iniciación y desarrollo de nódulos en aliso (alnus acuminata h.b.k)

OpenAIRE

Niño, Luz Marina; Pérez, Rosalia; Orozco de Amezquita, Martha; Garcés de Granada, Emira

2011-01-01

La especie nativa Alnus ecuminata H.B.K. (Aliso) establece una relación simbiótica en las raíces con un Actinomycete
del género Frankia. De esta asociación resulta la formación de nódulos que tienen capacidad para fijar nitrógeno atmosférico y mejorar la disponibilidad de este elemento
en los suelos. Para evaluar y analizar los cambios morfológicos originados por el establecimiento de la asociación, se inocularon con nódulos macerados plántulas de. Aliso sembradas en med...

Biotic and abiotic variables influencing plant litter breakdown in streams: a global study

Science.gov (United States)

Pearson, Richard G.; Hui, Cang; Gessner, Mark O.; Pérez, Javier; Alexandrou, Markos A.; Graça, Manuel A. S.; Cardinale, Bradley J.; Albariño, Ricardo J.; Arunachalam, Muthukumarasamy; Barmuta, Leon A.; Boulton, Andrew J.; Bruder, Andreas; Callisto, Marcos; Chauvet, Eric; Death, Russell G.; Dudgeon, David; Encalada, Andrea C.; Ferreira, Verónica; Figueroa, Ricardo; Flecker, Alexander S.; Gonçalves, José F.; Helson, Julie; Iwata, Tomoya; Jinggut, Tajang; Mathooko, Jude; Mathuriau, Catherine; M'Erimba, Charles; Moretti, Marcelo S.; Pringle, Catherine M.; Ramírez, Alonso; Ratnarajah, Lavenia; Rincon, José; Yule, Catherine M.

2016-01-01

Plant litter breakdown is a key ecological process in terrestrial and freshwater ecosystems. Streams and rivers, in particular, contribute substantially to global carbon fluxes. However, there is little information available on the relative roles of different drivers of plant litter breakdown in fresh waters, particularly at large scales. We present a global-scale study of litter breakdown in streams to compare the roles of biotic, climatic and other environmental factors on breakdown rates. We conducted an experiment in 24 streams encompassing latitudes from 47.8° N to 42.8° S, using litter mixtures of local species differing in quality and phylogenetic diversity (PD), and alder (Alnus glutinosa) to control for variation in litter traits. Our models revealed that breakdown of alder was driven by climate, with some influence of pH, whereas variation in breakdown of litter mixtures was explained mainly by litter quality and PD. Effects of litter quality and PD and stream pH were more positive at higher temperatures, indicating that different mechanisms may operate at different latitudes. These results reflect global variability caused by multiple factors, but unexplained variance points to the need for expanded global-scale comparisons. PMID:27122551

Activation-Strain Analysis Reveals Unexpected Origin of Fast Reactivity in Heteroaromatic Azadiene Inverse-Electron-Demand Diels-Alder Cycloadditions

NARCIS (Netherlands)

Talbot, Austin; Devarajan, Deepa; Gustafson, Samantha J.; Fernandez, Israel; Bickelhaupt, F. Matthias; Ess, Daniel H.

2014-01-01

Heteroaromatic azadienes, especially 1,2,4,5-tetrazines, are extremely reactive partners with alkenes in inverse-electron-demand Diels–Alder reactions. Azadiene cycloaddition reactions are used to construct heterocycles in synthesis and are popular as bioorthogonal reactions. The origin of fast

Assessment of a novel alder biorefinery concept to meet demands of economic feasibility, energy production and long term environmental sustainability

DEFF Research Database (Denmark)

Thomsen, Tobias; Ahrenfeldt, Jesper; Thomsen, Sune Tjalfe

2013-01-01

A biorefinery concept based on alder tree plantations on degenerated soil is developed to comply with indicators of economic feasibility, fossil fuel depletion concerns, and long term sustainability issues. The potential performance of feedstock and biorefinery has been assessed through a literat......A biorefinery concept based on alder tree plantations on degenerated soil is developed to comply with indicators of economic feasibility, fossil fuel depletion concerns, and long term sustainability issues. The potential performance of feedstock and biorefinery has been assessed through...... degenerated soils. Integrating a biomass handling system, an LTCFB gasifier, a diarylheptanoids production chain, an anaerobic digestion facility, a slow pyrolysis unit, gas upgrading and various system integration units, the biorefinery could obtain the following production characteristics accounted...

Silver-catalyzed formal inverse electron-demand Diels-Alder reaction of 1,2-diazines and siloxy alkynes.

Science.gov (United States)

Türkmen, Yunus E; Montavon, Timothy J; Kozmin, Sergey A; Rawal, Viresh H

2012-06-06

A highly effective silver-catalyzed formal inverse electron-demand Diels-Alder reaction of 1,2-diazines and siloxy alkynes has been developed. The reactions provide ready access to a wide range of siloxy naphthalenes and anthracenes, which are formed in good to high yields, under mild reaction conditions, using low catalyst loadings.

Asymmetric Diels-Alder Reaction of α,β-Unsaturated Oxazolidin-2-one Derivatives Catalyzed by a Chiral Fe(III)-Bipyridine Diol Complex.

Science.gov (United States)

Li, Mao; Carreras, Virginie; Jalba, Angela; Ollevier, Thierry

2018-02-16

An asymmetric Fe III -bipyridine diol catalyzed Diels-Alder reaction of α,β-unsaturated oxazolidin-2-ones has been developed. Among various Fe II /Fe III salts, Fe(ClO 4 ) 3 ·6H 2 O was selected as the Lewis acid of choice. The use of a low catalyst loading (2 mol % of Fe(ClO 4 ) 3 ·6H 2 O and 2.4 mol % of Bolm's ligand) afforded high yields (up to 99%) and high enantiomeric excesses (up to 98%) of endo-cycloadducts for the Diels-Alder reaction between cyclopentadiene and substituted acryloyloxazolidin-2-ones. Other noncyclic dienes led to decreased enantioselectivities. A proposed model supports the observed stereoinduction.

Origins of the Unfavorable Activation and Reaction Energies of 1-Azadiene Heterocycles Compared to 2-Azadiene Heterocycles in Diels-Alder Reactions.

Science.gov (United States)

Fell, Jason S; Martin, Blanton N; Houk, K N

2017-02-17

The reactivities of butadiene, cyclopentadiene, furan, thiophene, pyrrole, and their 1-aza- and 2-aza-derivatives in Diels-Alder reactions with ethylene and fumaronitrile were investigated with density functional theory (M06-2X/6-311G(d,p)). The activation free energies for the Diels-Alder reactions of cyclic 1-azadienes are 10-14 kcal mol -1 higher than those of cyclic 2-azadienes, and the reaction free energies are 17-20 kcal mol -1 more endergonic. The distortion/interaction model shows that the increased activation energies of cyclic 1-azadienes originate from increased transition state distortion energies and unfavorable interaction energies, arising from addition to the nitrogen terminus of the C═N bond.

Asymmetric aza-Diels-Alder reaction of Danishefsky's diene with imines in a chiral reaction medium

Directory of Open Access Journals (Sweden)

Pégot Bruce

2006-09-01

Full Text Available Abstract The asymmetric aza-Diels-Alder reaction of chiral imines with Danishefsky's diene in chiral ionic liquids provides the corresponding cycloadduct with moderate to high diastereoselectivity. The reaction has proved to perform better at room temperature in ionic liquids without either Lewis acid catalyst or organic solvent. Chiral ionic liquids are recycled while their efficiency is preserved.

The Intramolecular Diels–Alder Reaction of Tryptamine-Derived Zincke Aldehydes Is a Stepwise Process

OpenAIRE

Pham, Hung V.; Martin, David B. C.; Vanderwal, Christopher D.; Houk, K. N.

2012-01-01

Computational studies show that the base-mediated intramolecular Diels–Alder of tryptamine-derived Zincke aldehydes, used as a key step in the synthesis of the Strychnos alkaloids norfluorocurarine and strychnine, proceeds via a stepwise pathway. The experimentally determined importance of a potassium counterion in the base is explained by its ability to preorganize the Zincke aldehyde diene in an s-cis conformation suitable to bicyclization. Computation also supports the thermodynamic import...

Cross-linking of rubber in the presence of multi-functional cross-linking aids via thermoreversible Diels-Alder chemistry

NARCIS (Netherlands)

Polgar, L. M.; Fortunato, G.; Araya-Hermosilla, R.; van Duin, M.; Pucci, A.; Picchioni, F.

Furan-functionalized polyketone (PK-FU) was added to a furan-functionalized ethylene-propylene rubber (EPM-FU). The mixture was subsequently cross-linked with a bismaleimide through Diels-Alder chemistry in order to improve the mechanical properties of the rubber. Infrared spectroscopy showed the

Synthesis of terephthalic acid via Diels-Alder reactions with ethylene and oxidized variants of 5-hydroxymethylfurfural

Science.gov (United States)

Pacheco, Joshua J.; Davis, Mark E.

2014-01-01

Terephthalic acid (PTA), a monomer in the synthesis of polyethylene terephthalate (PET), is obtained by the oxidation of petroleum-derived p-xylene. There is significant interest in the synthesis of renewable, biomass-derived PTA. Here, routes to PTA starting from oxidized products of 5-hydroxymethylfurfural (HMF) that can be produced from biomass are reported. These routes involve Diels-Alder reactions with ethylene and avoid the hydrogenation of HMF to 2,5-dimethylfuran. Oxidized derivatives of HMF are reacted with ethylene over solid Lewis acid catalysts that do not contain strong Brønsted acids to synthesize intermediates of PTA and its equally important diester, dimethyl terephthalate (DMT). The partially oxidized HMF, 5-(hydroxymethyl)furoic acid (HMFA), is reacted with high pressure ethylene over a pure-silica molecular sieve containing framework tin (Sn-Beta) to produce the Diels-Alder dehydration product, 4-(hydroxymethyl)benzoic acid (HMBA), with 31% selectivity at 61% HMFA conversion after 6 h at 190 °C. If HMFA is protected with methanol to form methyl 5-(methoxymethyl)furan-2-carboxylate (MMFC), MMFC can react with ethylene in the presence of Sn-Beta for 2 h to produce methyl 4-(methoxymethyl)benzenecarboxylate (MMBC) with 46% selectivity at 28% MMFC conversion or in the presence of a pure-silica molecular sieve containing framework zirconium (Zr-Beta) for 6 h to produce MMBC with 81% selectivity at 26% MMFC conversion. HMBA and MMBC can then be oxidized to produce PTA and DMT, respectively. When Lewis acid containing mesoporous silica (MCM-41) and amorphous silica, or Brønsted acid containing zeolites (Al-Beta), are used as catalysts, a significant decrease in selectivity/yield of the Diels-Alder dehydration product is observed. PMID:24912153

Germination of red alder (Alnus rubra) seed from several locations in its natural range

Energy Technology Data Exchange (ETDEWEB)

Elliott, D.M.; Taylor, I.E.P.

1981-01-01

Tests were carried out on stratified, pre-soaked or untreated seeds. Germination of all provenances and treatments was more than 90%, except for one provenance showing physiological dormancy in which germination was low, but increased significantly with stratification and presoaking; dormancy could be broken completely by chilling at 0 degrees C for 5 days. Significant interactions were found between provenances and treatments for both germination % and seed vigour (as measured by germination value).

Hydrogen Abstraction Acetylene Addition and Diels-Alder Mechanisms of PAH Formation:  A Detailed Study Using First Principles Calculations.

Science.gov (United States)

Kislov, V V; Islamova, N I; Kolker, A M; Lin, S H; Mebel, A M

2005-09-01

Extensive ab initio Gaussian-3-type calculations of potential energy surfaces (PES), which are expected to be accurate within 1-2 kcal/mol, combined with statistical theory calculations of reaction rate constants have been applied to study various possible pathways in the hydrogen abstraction acetylene addition (HACA) mechanism of naphthalene and acenaphthalene formation as well as Diels-Alder pathways to acenaphthalene, phenanthrene, and pyrene. The barrier heights; reaction energies; and molecular parameters of the reactants, products, intermediates, and transition states have been generated for all types of reactions involved in the HACA and Diels-Alder mechanisms, including H abstraction from various aromatic intermediates, acetylene addition to radical sites, ring closures leading to the formation of additional aromatic rings, elimination of hydrogen atoms, H disproportionation, C2H2 cycloaddition, and H2 loss. The reactions participating in various HACA sequences (e.g., Frenklach's, alternative Frenklach's, and Bittner and Howard's routes) are demonstrated to have relatively low barriers and high rate constants under combustion conditions. A comparison of the significance of different HACA mechanisms in PAH growth can be made in the future using PES and molecular parameters obtained in the present work. The results show that the Diels-Alder mechanism cannot compete with the HACA pathways even at high combustion temperatures, because of high barriers and consequently low reaction rate constants. The calculated energetic parameters and rate constants have been compared with experimental and theoretical data available in the literature.

The inverse electron demand Diels-Alder click reaction in radiochemistry.

Science.gov (United States)

Reiner, Thomas; Zeglis, Brian M

2014-04-01

The inverse electron-demand Diels-Alder (IEDDA) cycloaddition between 1,2,4,5-tetrazines and strained alkene dienophiles is an emergent variety of catalyst-free 'click' chemistry that has the potential to have a transformational impact on the synthesis and development of radiopharmaceuticals. The ligation is selective, rapid, high-yielding, clean, and bioorthogonal and, since its advent in 2008, has been employed in a wide variety of chemical settings. In radiochemistry, the reaction has proven particularly useful with (18)  F and has already been utilized to create a number of (18)  F-labeled agents, including the PARP1-targeting small molecule (18)  F-AZD2281, the αv β3 integrin-targeting peptide (18)  F-RGD, and the GLP-1-targeting peptide (18)  F-exendin. The inherent flexibility of the ligation has also been applied to the construction of radiometal-based probes, specifically the development of a modular strategy for the synthesis of radioimmunoconjugates that effectively eliminates variability in the construction of these agents. Further, the exceptional speed and biorthogonality of the reaction have made it especially promising in the realm of in vivo pretargeted imaging and therapy, and pretargeted imaging strategies based on the isotopes (111) In, (18)  F, and (64) Cu have already proven capable of producing images with high tumor contrast and low levels of uptake in background, nontarget organs. Ultimately, the characteristics of inverse electron-demand Diels-Alder click chemistry make it almost uniquely well-suited for radiochemistry, and although the field is young, this ligation has the potential to make a tremendous impact on the synthesis, development, and study of novel radiopharmaceuticals. Copyright © 2013 John Wiley & Sons, Ltd.

First catalytic hetero-Diels-Alder reaction of imidazole-2-thiones and in silico biological evaluation of the cycloadducts

NARCIS (Netherlands)

Eleftheriadis, Nikolaos; Samatidou, Evanthia; Neochoritis, Constantinos G.

The Lewis acid-catalyzed Diels-Alder reactions of suitably substituted imidazole-2-thiones with dienes were studied. It was found that the electron density of the imidazole core influenced the reaction, since electron withdrawing groups led to the novel spiro-derivatives 2 whereas electron donating

Microwave-Enhanced Organic Syntheses for the Undergraduate Laboratory: Diels-Alder Cycloaddition, Wittig Reaction, and Williamson Ether Synthesis

Science.gov (United States)

Baar, Marsha R.; Falcone, Danielle; Gordon, Christopher

2010-01-01

Microwave heating enhanced the rate of three reactions typically performed in our undergraduate organic chemistry laboratory: a Diels-Alder cycloaddition, a Wittig salt formation, and a Williamson ether synthesis. Ninety-minute refluxes were shortened to 10 min using a laboratory-grade microwave oven. In addition, yields improved for the Wittig…

A Thermal Dehydrogenative Diels–Alder Reaction of Styrenes for the Concise Synthesis of Functionalized Naphthalenes

Science.gov (United States)

Kocsis, Laura S.; Benedetti, Erica

2012-01-01

Functionalized naphthalenes are valuable building blocks in many important areas. A microwave-assisted, intramolecular dehydrogenative Diels-Alder reaction of styrenyl derivatives to provide cyclopenta[b]naphthalene substructures not previously accessible using existing synthetic methods is described. The synthetic utility of these uniquely functionalized naphthalenes was demonstrated by a single-step conversion of one of these cycloadducts to a fluorophore bearing a structural resemblance to Prodan. PMID:22913473

A thermal dehydrogenative Diels-Alder reaction of styrenes for the concise synthesis of functionalized naphthalenes.

Science.gov (United States)

Kocsis, Laura S; Benedetti, Erica; Brummond, Kay M

2012-09-07

Functionalized naphthalenes are valuable building blocks in many important areas. A microwave-assisted, intramolecular dehydrogenative Diels-Alder reaction of styrenyl derivatives to provide cyclopenta[b]naphthalene substructures not previously accessible using existing synthetic methods is described. The synthetic utility of these uniquely functionalized naphthalenes was demonstrated by a single-step conversion of one of these cycloadducts to a fluorophore bearing a structural resemblance to Prodan.

Substituent Effects on Regioselectivity of the Diels-Alder Reactions: Reactions of 10-Allyl-1,8-dichloroanthracene with 2-Chloroacrylonitrile, 1-Cyanovinyl Acetate and Phenyl Vinyl Sulfone

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Mujeeb A. Sultan

2016-01-01

Full Text Available Diels-Alder reaction of 10-allyl-1,8-dichloroanthracene (3 with 2-chloroacrylonitrile (4 and 1-cyanovinyl acetate (5 gives exclusively the ortho isomer while its reaction with phenyl vinyl sulfone (10 yields a mixture of two isomeric adducts with priority to ortho isomer. The reactions proceeded under microwave condition in xylene. Configurations of these isomers have been assigned with the help of NMR spectra. The results indicated that the steric effect is dominating toward the isomer regioselectivity in the Diels-Alder reaction of the present compounds.

Investigating radical cation chain processes in the electrocatalytic Diels-Alder reaction.

Science.gov (United States)

Imada, Yasushi; Okada, Yohei; Chiba, Kazuhiro

2018-01-01

Single electron transfer (SET)-triggered radical ion-based reactions have proven to be powerful options in synthetic organic chemistry. Although unique chain processes have been proposed in various photo- and electrochemical radical ion-based transformations, the turnover number, also referred to as catalytic efficiency, remains unclear in most cases. Herein, we disclose our investigations of radical cation chain processes in the electrocatalytic Diels-Alder reaction, leading to a scalable synthesis. A gram-scale synthesis was achieved with high current efficiency of up to 8000%. The reaction monitoring profiles showed sigmoidal curves with induction periods, suggesting the involvement of intermediate(s) in the rate determining step.

A Tri-O-Bridged Diels-Alder Adduct from Cortex Mori Radicis

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An-Qi Lu

2018-01-01

Full Text Available Sanggenon X, an unusual tri-O-bridged Diels-Alder adduct, was isolated from Cortex Mori Radicis. Its structure was established by spectroscopic analysis, including NMR and HR-MS (High Resolution Mass Spectrometry. Sanggenon X contained three O-bridged rings, where the oxygenated bridgeheads were all quaternary carbons. Chemical methylation was carried out to deduce the linkages of the three O-bridges. The absolute configuration was determined by calculating the ECD (Electronic Circular Dichroism using the TDDFT (Time-Dependent Density Functional Theory method. Sanggenon X showed significant antioxidant activity against Fe2+-Cys-induced lipid peroxidation in rat liver microsomes, and was as effective as the positive control, curcumin.

Organoplatinum complex promoted the asymmetric endo stereochemically controlled Diels-Alder reaction between 3-diphenylphosphinofuran and diphenylvinylphosphine.

Science.gov (United States)

Liu, Fengli; Pullarkat, Sumod A; Tan, Kien-Wee; Li, Yongxin; Leung, Pak-Hing

2009-12-07

The organoplatinum complex containing ortho-metalated (R)-(1-(dimethylamino)ethyl)-naphthalene as the chiral auxiliary has been used efficiently to promote the asymmetric [4 + 2] Diels-Alder reaction between diphenylvinylphosphine and 3-diphenylphosphinofuran to generate two chelating diphosphine endocycloadducts in the ratio 17:1. The absolute configurations of the three newly generated stereocenters have been assigned by single-crystal X-ray analysis.

N,N-Diethyl-1-Tosyl-3-Indoleglyoxylamide as a Dienophile in Diels-Alder Reactions. Hyperbaric vs. Thermal Conditions

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B. Biolatto

2000-03-01

Full Text Available Under high pressure conditions, the Diels-Alder reaction involving N,N-diethyl-1-tosyl-3-indoleglyoxylamide and 1-(N-acetyl-N-propylamino-1,3-butadiene produces a highly functionalized intermediate for the synthesis of Indole Alkaloids, in shorter times and higher yields than under thermal conditions.

Diels-Alder Synthesis of endo-cis-N-phenylbicyclo[2.2.2]oct-5-en-2,3-dicarboximide

Science.gov (United States)

Baar, Marsha R.; Wustholz, Kristin

2005-01-01

A study investigated the Diels-Alder synthesis of endo-cis-N-phenylbicyclo [2.2.2]oct-5-en-2,3-dicarboximide. The amount of time taken by a reaction between the 1,3-cyclohexadiene and N-phenylmaleimide at room temperature and also whether the desired cycloadduct would precipitate directly from the reaction mixture was examined.

Ti(Oi-Pr)4-promoted photoenolization Diels-Alder reaction to construct polycyclic rings and its synthetic applications.

Science.gov (United States)

Yang, Baochao; Lin, Kuaikuai; Shi, Yingbo; Gao, Shuanhu

2017-09-20

Stereoselective construction of polycyclic rings with all-carbon quaternary centers, and vicinal all-carbon quaternary stereocenters, remains a significant challenge in organic synthesis. These structures can be found in a wide range of polycyclic natural products and drug molecules. Here we report a Ti(Oi-Pr) 4 -promoted photoenolization/Diels-Alder (PEDA) reaction to construct hydroanthracenol and related polycyclic rings bearing all-carbon quaternary centers. This photolysis proceeds under mild conditions and generates a variety of photo-cycloaddition products in good reaction efficiency and stereoselectivity (48 examples), and has been successfully used in the construction of core skeleton of oncocalyxones, tetracycline and pleurotin. It also provides a reliable method for the late-stage modification of natural products bearing enone groups, such as steroids. The total synthesis of oncocalyxone B was successfully achieved using this PEDA approach.Anthracenols with multiple chiral centres are common motifs in natural products. Here, the authors show a highly stereoselective photoenolization/Diels-Alder methodology involving a key Lewis acid reagent enabling the efficient construction of a family of anthracenol derivatives with quaternary centers.

Lateral extension of π conjugation along the bay regions of bisanthene through a diels-alder cycloaddition reaction

KAUST Repository

Li, Jinling; Jiao, Chongjun; Huang, Kuo-Wei; Wu, Jishan

2011-01-01

Diels-Alder cycloaddition reactions at the bay regions of bisanthene (1) with dienophiles such as 1,4-naphthoquinone have been investigated. The products were submitted to nucleophilic addition followed by reductive aromatization reactions to afford the laterally extended bisanthene derivatives 2 and 3. Attempted synthesis of a larger expanded bisanthene 4 revealed an unexpected hydrogenation reaction at the last reductive aromatization step. Unusual Michael addition was observed on quinone 14, which was obtained by Diels-Alder reaction between 1 and 1,4-anthraquinone. Compounds 1-3 exhibited near-infrared (NIR) absorption and emission with high-to-moderate fluorescent quantum yields. Their structures and absorption spectra were studied by density function theory and non-planar twisted structures were calculated for 2 and 3. All compounds showed amphoteric redox behavior with multiple oxidation/reduction waves. Oxidative titration with SbCl 5 gave stable radical cations, and the process was followed by UV/Vis/NIR spectroscopic measurements. Their photostability was measured and correlated to their different geometries and electronic structures. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lateral extension of π conjugation along the bay regions of bisanthene through a diels-alder cycloaddition reaction

KAUST Repository

Li, Jinling

2011-11-14

Diels-Alder cycloaddition reactions at the bay regions of bisanthene (1) with dienophiles such as 1,4-naphthoquinone have been investigated. The products were submitted to nucleophilic addition followed by reductive aromatization reactions to afford the laterally extended bisanthene derivatives 2 and 3. Attempted synthesis of a larger expanded bisanthene 4 revealed an unexpected hydrogenation reaction at the last reductive aromatization step. Unusual Michael addition was observed on quinone 14, which was obtained by Diels-Alder reaction between 1 and 1,4-anthraquinone. Compounds 1-3 exhibited near-infrared (NIR) absorption and emission with high-to-moderate fluorescent quantum yields. Their structures and absorption spectra were studied by density function theory and non-planar twisted structures were calculated for 2 and 3. All compounds showed amphoteric redox behavior with multiple oxidation/reduction waves. Oxidative titration with SbCl 5 gave stable radical cations, and the process was followed by UV/Vis/NIR spectroscopic measurements. Their photostability was measured and correlated to their different geometries and electronic structures. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of 2,5-Disubstituted Octahydroquinolin-4-ones via anIntramolecular Hetero Diels-Alder Reaction

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J. Antonio Palenzuela

2007-02-01

Full Text Available A route for the preparation of 2,5-disubstituted octahydroquinolin-4-ones, synthetic precursors of the decahydroquinoline-type toxins, is presented. The key steps are an asymmetric epoxidation and an intramolecular hetero Diels-Alder reaction between an activated diene and an imine. The presence of an allylic stereogenic center induces some selectivity and thus only two cycloadducts are obtained in 70:30 ratio and good yield.

Continuous-flow retro-Diels-Alder reaction: an efficient method for the preparation of pyrimidinone derivatives.

Science.gov (United States)

Nekkaa, Imane; Palkó, Márta; Mándity, István M; Fülöp, Ferenc

2018-01-01

The syntheses of various pyrimidinones as potentially bioactive products by means of the highly controlled continuous-flow retro-Diels-Alder reaction of condensed pyrimidinone derivatives are presented. Noteworthy, the use of this approach allowed us to rapidly screen a selection of conditions and quickly confirm the viability of preparing the desired pyrimidinones in short reaction times. Yields typically higher than those published earlier using conventional batch or microwave processes were achieved.

Procesos morfológicos en la iniciación y desarrollo de nódulos en aliso (Alnus acuminata H.B.K

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Niño Luz Marina

1987-12-01

Full Text Available La especie nativa Alnus ecuminata H.B.K. (Aliso establece una relación simbiótica en las raíces con un Actinomycete
del género Frankia. De esta asociación resulta la formación de nódulos que tienen capacidad para fijar nitrógeno atmosférico y mejorar la disponibilidad de este elemento
en los suelos. Para evaluar y analizar los cambios morfológicos originados por el establecimiento de la asociación, se inocularon con nódulos macerados plántulas de. Aliso sembradas en medio estéril. Periódicamente, a partir de los tratamientos, las raíces de Aliso fueron muestradas y procesadas empleando técnicas de microscopía óptica y electrónica. Las observaciones efectuadas mostraron
al simbionte en cuatro formas: esporas, hifas, ves ículas y bacteroides y revelaron que el proceso de iniciación y desarrollo de los nódulos fue similar al de otras especies del
género Alnus estudiadas en las Zonas templadas. Frankia penetró a los tejidos de la planta vía pelo radical, invadió luego el tejido cortical e indujo la formación del nódulo, el cual emergió a manera de una raíz lateral. Además se estableció que la hifas forma inefectiva de Frankia, penetró por células epidermales jóvenes. En estadios iniciales de infección, el Actinomycete se encontró en espacios intercelulares, aunque siempre terminó estableciéndose en células del tejido cortical.

Use of Diels-Alder Chemistry for Thermoreversible Cross-Linking of Rubbers : The Next Step toward Recycling of Rubber Products?

NARCIS (Netherlands)

Polgar, L. M.; van Duin, M.; Broekhuis, A. A.; Picchioni, F.

2015-01-01

A proof of principle for the use of Diels-Alder chemistry as a thermoreversible cross-linking tool for rubber products is demonstrated. A commercial ethylene-propylene rubber grafted with maleic anhydride has been thermoreversibly cross-linked in two steps. The pending anhydride rings were first

Magnetic hyaluronic acid nanospheres via aqueous Diels-Alder chemistry to deliver dexamethasone for adipose tissue engineering.

Science.gov (United States)

Jia, Yang; Fan, Ming; Chen, Huinan; Miao, Yuting; Xing, Lian; Jiang, Bohong; Cheng, Qifan; Liu, Dongwei; Bao, Weikang; Qian, Bin; Wang, Jionglu; Xing, Xiaodong; Tan, Huaping; Ling, Zhonghua; Chen, Yong

2015-11-15

Biopolymer-based nanospheres have great potential in the field of drug delivery and tissue regenerative medicine. In this work, we present a flexible way to conjugate a magnetic hyaluronic acid (HA) nanosphere system that are capable of vectoring delivery of adipogenic factor, e.g. dexamethasone, for adipose tissue engineering. Conjugation of nanospheres was established by aqueous Diels-Alder chemistry between furan and maleimide of HA derivatives. Simultaneously, a furan functionalized dexamethasone peptide, GQPGK, was synthesized and covalently immobilized into the nanospheres. The magnetic HA nanospheres were fabricated by encapsulating super-paramagnetic iron oxide nanoparticles, which exhibited quick magnetic sensitivity. The aqueous Diels-Alder chemistry made nanospheres high binding efficiency of dexamethasone, and the vectoring delivery of dexamethasone could be easily controlled by a external magnetic field. The potential application of the magnetic HA nanospheres on vectoring delivery of adipogenic factor was confirmed by co-culture of human adipose-derived stem cells (ASCs). In vitro cytotoxicity tests demonstrated that incorporation of dexamethasone into magnetic HA nanospheres showed high efficiency to promote ASCs viabilities, in particular under a magnetic field, which suggested a promising future for adipose regeneration applications. Copyright © 2015 Elsevier Inc. All rights reserved.

Synthesis of Precursors of the Agalacto (Exo) Fragment of the Quartromicins via an Auxiliary-Controlled Exo-Selective Diels-Alder Reaction

Science.gov (United States)

Qi, Jun; Roush, William R.

2008-01-01

A direct synthesis of the α-hydroxyaldehyde exo-5, a precursor of the exo-spirotetronate subunit o f the quartromicins, was achieved through an exo-selective Lewis acid-catalyzed Diels-Alder reaction of dienophile 12a and diene 1. PMID:16774259

Facile approach to prepare pH and redox-responsive nanogels via Diels-Alder click reaction

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C. M. Q. Le

2018-08-01

Full Text Available A novel pH and redox responsive system of sub-100 nm nanogels was prepared by arm-first approach via Diels-Alder click reaction. First, well-defined poly(ethylene glycol-block-poly(styrene-alt-maleic anhydride (PEG-b-PSM was synthesized and subsequently functionalized with furfuryl amine, leading to the formation of the dual-functional block copolymer of PEG-b-PSMf. The furfuryl groups in the PSMf block were employed to incorporate a redox-responsive linkage and the carboxylic acid moieties generated through functionalization acted as a pH-responsive part. The Diels-Alder click reaction between a bismaleimide crosslinker and PEG-b-PSMf was conducted at 60 °C, affording star-like nanogel structures. Doxorubicin, a model anticancer drug, was loaded into to the core of the nanogels primarily by the ionic interaction with carboxylates of core blocks and a highest drug loading capacity of 38.1% was obtained. Furthermore, the in vitro profile showed a low release percentage (11.2% of DOX at PBS pH 7.4, whereas a burst release (62% at pH 5.0 in the presence of 10 mM glutathione, indicating the effective pH and redox responsive characteristic of the PEG-b-PSMf nanogels.

Towards green loyalty: the influences of green perceived risk, green image, green trust and green satisfaction

Science.gov (United States)

Chrisjatmiko, K.

2018-01-01

The paper aims to present a comprehensive framework for the influences of green perceived risk, green image, green trust and green satisfaction to green loyalty. The paper also seeks to account explicitly for the differences in green perceived risk, green image, green trust, green satisfaction and green loyalty found among green products customers. Data were obtained from 155 green products customers. Structural equation modeling was used in order to test the proposed hypotheses. The findings show that green image, green trust and green satisfaction has positive effects to green loyalty. But green perceived risk has negative effects to green image, green trust and green satisfaction. However, green perceived risk, green image, green trust and green satisfaction also seems to be a good device to gain green products customers from competitors. The contributions of the paper are, firstly, a more complete framework of the influences of green perceived risk, green image, green trust and green satisfaction to green loyalty analyses simultaneously. Secondly, the study allows a direct comparison of the difference in green perceived risk, green image, green trust, green satisfaction and green loyalty between green products customers.

The Nitrosocarbonyl Hetero-Diels–Alder Reaction as a Useful Tool for Organic Syntheses

Science.gov (United States)

Bodnar, Brian S.

2014-01-01

Organic transformations that result in the formation of multiple covalent bonds within the same reaction are some of the most powerful tools in synthetic organic chemistry. Nitrosocarbonyl hetero-Diels–Alder (HDA) reactions allow for the simultaneous stereospecific introduction of carbon–nitrogen and carbon–oxygen bonds in one synthetic step, and provide direct access to 3,6-dihydro-1,2-oxazines. This Review describes the development of the nitrosocarbonyl HDA reaction and the utility of the resulting oxazine ring in the synthesis of a variety of important, biologically active molecules. PMID:21520360

Synthesis of α- and β-lapachone derivatives from hetero diels-alder trapping of alkyl and aryl o-quinone methides

International Nuclear Information System (INIS)

Silva, Fernando de C. da; Ferreira, Sabrina B.; Ferreira, Vitor F.; Kaiser, Carlos R.; Pinto, Angelo C.

2009-01-01

Methylene and aryl o-quinone methides (o-QMs) generated by Knoevenagel condensation of 2-hydroxy-1,4-naphthoquinone with formaldehyde and arylaldehydes, undergo facile hetero Diels-Alder reaction with some substituted styrenes (as dienophiles) in aqueous ethanol media providing derivatives of α- and β-lapachone (author)

Simultaneous analysis of 70 pesticides using HPlc/MS/MS: a comparison of the multiresidue method of Klein and Alder and the QuEChERS method.

Science.gov (United States)

Riedel, Melanie; Speer, Karl; Stuke, Sven; Schmeer, Karl

2010-01-01

Since 2003, two new multipesticide residue methods for screening crops for a large number of pesticides, developed by Klein and Alder and Anastassiades et al. (Quick, Easy, Cheap, Effective, Rugged, and Safe; QuEChERS), have been published. Our intention was to compare these two important methods on the basis of their extraction efficiency, reproducibility, ruggedness, ease of use, and speed. In total, 70 pesticides belonging to numerous different substance classes were analyzed at two concentration levels by applying both methods, using five different representative matrixes. In the case of the QuEChERS method, the results of the three sample preparation steps (crude extract, extract after SPE, and extract after SPE and acidification) were compared with each other and with the results obtained with the Klein and Alder method. The extraction efficiencies of the QuEChERS method were far higher, and the sample preparation was much quicker when the last two steps were omitted. In most cases, the extraction efficiencies after the first step were approximately 100%. With extraction efficiencies of mostly less than 70%, the Klein and Alder method did not compare favorably. Some analytes caused problems during evaluation, mostly due to matrix influences.

Diels-Alder functionalized carbon nanotubes for bone tissue engineering: in vitro/in vivo biocompatibility and biodegradability

Science.gov (United States)

Mata, D.; Amaral, M.; Fernandes, A. J. S.; Colaço, B.; Gama, A.; Paiva, M. C.; Gomes, P. S.; Silva, R. F.; Fernandes, M. H.

2015-05-01

The risk-benefit balance for carbon nanotubes (CNTs) dictates their clinical fate. To take a step forward at this crossroad it is compulsory to modulate the CNT in vivo biocompatibility and biodegradability via e.g. chemical functionalization. CNT membranes were functionalised combining a Diels-Alder cycloaddition reaction to generate cyclohexene (-C6H10) followed by a mild oxidisation to yield carboxylic acid groups (-COOH). In vitro proliferation and osteogenic differentiation of human osteoblastic cells were maximized on functionalized CNT membranes (p,f-CNTs). The in vivo subcutaneously implanted materials showed a higher biological reactivity, thus inducing a slighter intense inflammatory response compared to non-functionalized CNT membranes (p-CNTs), but still showing a reduced cytotoxicity profile. Moreover, the in vivo biodegradation of CNTs was superior for p,f-CNT membranes, likely mediated by the oxidation-induced myeloperoxidase (MPO) in neutrophil and macrophage inflammatory milieus. This proves the biodegradability faculty of functionalized CNTs, which potentially avoids long-term tissue accumulation and triggering of acute toxicity. On the whole, the proposed Diels-Alder functionalization accounts for the improved CNT biological response in terms of the biocompatibility and biodegradability profiles. Therefore, CNTs can be considered for use in bone tissue engineering without notable toxicological threats.The risk-benefit balance for carbon nanotubes (CNTs) dictates their clinical fate. To take a step forward at this crossroad it is compulsory to modulate the CNT in vivo biocompatibility and biodegradability via e.g. chemical functionalization. CNT membranes were functionalised combining a Diels-Alder cycloaddition reaction to generate cyclohexene (-C6H10) followed by a mild oxidisation to yield carboxylic acid groups (-COOH). In vitro proliferation and osteogenic differentiation of human osteoblastic cells were maximized on functionalized CNT

Illustrating the Utility of X-Ray Crystallography for Structure Elucidation through a Tandem Aldol Condensation/Diels-Alder Reaction Sequence

Science.gov (United States)

Hoang, Giang T.; Kubo, Tomohiro; Young, Victor G., Jr.; Kautzky, Jacob A.; Wissinger, Jane E.

2015-01-01

Two introductory organic chemistry laboratory experiments are described based on the Diels-Alder reaction of 2,3,4,5-tetraphenylcyclopentadienone, which is synthesized prior to or in a one-pot reaction, with styrene. Students are presented with three possible products, the "endo" and "exo" diastereomers and the decarbonylated…

Highly Regio- and Stereoselective Diels-Alder Cycloadditions via Two-Step and Multicomponent Reactions Promoted by Infrared Irradiation under Solvent-Free Conditions

Science.gov (United States)

Flores-Conde, Maria Ines; Reyes, Leonor; Herrera, Rafael; Rios, Hulme; Vazquez, Miguel A.; Miranda, Rene; Tamariz, Joaquin; Delgado, Francisco

2012-01-01

Infrared irradiation promoted the Diels-Alder cycloadditions of exo-2-oxazolidinone dienes 1–3 with the Knoevenagel adducts 4–6, as dienophiles, leading to the synthesis of new 3,5-diphenyltetrahydrobenzo[d]oxazol-2-one derivatives (7, 9, 11 and 13–17), under solvent-free conditions. These cycloadditions were performed with good regio- and stereoselectivity, favoring the para-endo cycloadducts. We also evaluated the one-pot three-component reaction of active methylene compounds 20, benzaldehydes 21 and exo-2-oxazolidinone diene 2 under the same reaction conditions. A cascade Knoevenagel condensation/Diels-Alder cycloaddition reaction was observed, resulting in the final adducts 13–16 in similar yields. These procedures are environmentally benign, because no solvent and no catalyst were employed in these processes. The regioselectivity of these reactions was rationalized by Frontier Molecular Orbital (FMO) calculations. PMID:22489113

Highly Regio- and Stereoselective Diels-Alder Cycloadditions via Two-Step and Multicomponent Reactions Promoted by Infrared Irradiation under Solvent-Free Conditions

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Francisco Delgado

2012-02-01

Full Text Available Infrared irradiation promoted the Diels-Alder cycloadditions of exo-2-oxazolidinone dienes 1–3 with the Knoevenagel adducts 4–6, as dienophiles, leading to the synthesis of new 3,5-diphenyltetrahydrobenzo[d]oxazol-2-one derivatives (7, 9, 11 and 13–17, under solvent-free conditions. These cycloadditions were performed with good regio- and stereoselectivity, favoring the para-endo cycloadducts. We also evaluated the one-pot three-component reaction of active methylene compounds 20, benzaldehydes 21 and exo-2-oxazolidinone diene 2 under the same reaction conditions. A cascade Knoevenagel condensation/Diels-Alder cycloaddition reaction was observed, resulting in the final adducts 13–16 in similar yields. These procedures are environmentally benign, because no solvent and no catalyst were employed in these processes. The regioselectivity of these reactions was rationalized by Frontier Molecular Orbital (FMO calculations.

Actinorhizal Alder Phytostabilization Alters Microbial Community Dynamics in Gold Mine Waste Rock from Northern Quebec: A Greenhouse Study.

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Katrina L Callender

Full Text Available Phytotechnologies are rapidly replacing conventional ex-situ remediation techniques as they have the added benefit of restoring aesthetic value, important in the reclamation of mine sites. Alders are pioneer species that can tolerate and proliferate in nutrient-poor, contaminated environments, largely due to symbiotic root associations with the N2-fixing bacteria, Frankia and ectomycorrhizal (ECM fungi. In this study, we investigated the growth of two Frankia-inoculated (actinorhizal alder species, A. crispa and A. glutinosa, in gold mine waste rock from northern Quebec. Alder species had similar survival rates and positively impacted soil quality and physico-chemical properties in similar ways, restoring soil pH to neutrality and reducing extractable metals up to two-fold, while not hyperaccumulating them into above-ground plant biomass. A. glutinosa outperformed A. crispa in terms of growth, as estimated by the seedling volume index (SVI, and root length. Pyrosequencing of the bacterial 16S rRNA gene for bacteria and the ribosomal internal transcribed spacer (ITS region for fungi provided a comprehensive, direct characterization of microbial communities in gold mine waste rock and fine tailings. Plant- and treatment-specific shifts in soil microbial community compositions were observed in planted mine residues. Shannon diversity and the abundance of microbes involved in key ecosystem processes such as contaminant degradation (Sphingomonas, Sphingobium and Pseudomonas, metal sequestration (Brevundimonas and Caulobacter and N2-fixation (Azotobacter, Mesorhizobium, Rhizobium and Pseudomonas increased over time, i.e., as plants established in mine waste rock. Acetate mineralization and most probable number (MPN assays showed that revegetation positively stimulated both bulk and rhizosphere communities, increasing microbial density (biomass increase of 2 orders of magnitude and mineralization (five-fold. Genomic techniques proved useful in

Stream and floodplain restoration in a riparian ecosystem disturbed by placer mining

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Karle, Kenneth F.; Densmore, Roseann V.

1994-01-01

Techniques for the hydrologic restoration of placer-mined streams and floodplains were developed in Denali National Park and Preserve Alaska, USA. The hydrologic study focused on a design of stream and floodplain geometry using hydraulic capacity and shear stress equations. Slope and sinuosity values were based on regional relationships. Design requirements include a channel capacity for a 1.5-year (bankfull) discharge and a floodplain capacity for a 1.5- to 100-year discharge. Concern for potential damage to the project from annual flooding before natural revegetation occurs led to development of alder (Alnus crispa) brush bars to dissipate floodwater energy and encourage sediment deposition. The brush bars, constructed of alder bundles tied together and anchored laterally adjacent to the channel, were installed on the floodplain in several configurations to test their effectiveness. A moderate flood near the end of the two-year construction phase of the project provided data on channel design, stability, floodplain erosion, and brush bar effectiveness. The brush bars provided substantial protection, but unconsolidated bank material and a lack of bed armour for a new channel segment led to some bank erosion, slope changes and an increase in sinuosity in several reaches of the study area.

Design and synthesis of fused polycycles via Diels–Alder reaction and ring-rearrangement metathesis as key steps

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Sambasivarao Kotha

2015-07-01

Full Text Available Atom efficient processes such as the Diels–Alder reaction (DA and the ring-rearrangement metathesis (RRM have been used to design new polycycles. In this regard, ruthenium alkylidene catalysts are effective in realizing the RRM of bis-norbornene derivatives prepared by DA reaction and Grignard addition. Here, fused polycycles are assembled which are difficult to produce by conventional synthetic routes.

Design and synthesis of fused polycycles via Diels-Alder reaction and ring-rearrangement metathesis as key steps.

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Kotha, Sambasivarao; Ravikumar, Ongolu

2015-01-01

Atom efficient processes such as the Diels-Alder reaction (DA) and the ring-rearrangement metathesis (RRM) have been used to design new polycycles. In this regard, ruthenium alkylidene catalysts are effective in realizing the RRM of bis-norbornene derivatives prepared by DA reaction and Grignard addition. Here, fused polycycles are assembled which are difficult to produce by conventional synthetic routes.

Biodegradable hyaluronic acid hydrogels to control release of dexamethasone through aqueous Diels-Alder chemistry for adipose tissue engineering.

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Fan, Ming; Ma, Ye; Zhang, Ziwei; Mao, Jiahui; Tan, Huaping; Hu, Xiaohong

2015-11-01

A robust synthetic strategy of biopolymer-based hydrogels has been developed where hyaluronic acid derivatives reacted through aqueous Diels-Alder chemistry without the involvement of chemical catalysts, allowing for control and sustain release of dexamethasone. To conjugate the hydrogel, furan and maleimide functionalized hyaluronic acid were synthesized, respectively, as well as furan functionalized dexamethasone, for the covalent immobilization. Chemical structure, gelation time, morphologies, swelling kinetics, weight loss, compressive modulus and dexamethasone release of the hydrogel system in PBS at 37°C were studied. The results demonstrated that the aqueous Diels-Alder chemistry provides an extremely selective reaction and proceeds with high efficiency for hydrogel conjugation and covalent immobilization of dexamethasone. Cell culture results showed that the dexamethasone immobilized hydrogel was noncytotoxic and preserved proliferation of entrapped human adipose-derived stem cells. This synthetic approach uniquely allows for the direct fabrication of biologically functionalized gel scaffolds with ideal structures for adipose tissue engineering, which provides a competitive alternative to conventional conjugation techniques such as copper mediated click chemistry. Copyright © 2015. Published by Elsevier B.V.

C2-symmetric bisamidines: Chiral Brønsted bases catalysing the Diels-Alder reaction of anthrones

Directory of Open Access Journals (Sweden)

2008-08-01

Full Text Available C2-symmetric bisamidines 8 have been tested as chiral Brønsted bases in the Diels-Alder reaction of anthrones and N-substituted maleimides. High yields of cycloadducts and significant asymmetric inductions up to 76% ee are accessible. The proposed mechanism involves proton transfer between anthrone and bisamidine, association of the resulting ions and finally a cycloaddition step stereoselectively controlled by the chiral ion pair.

A 11-Steps Total Synthesis of Magellanine through a Gold(I)-Catalyzed Dehydro Diels-Alder Reaction.

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McGee, Philippe; Bétournay, Geneviève; Barabé, Francis; Barriault, Louis

2017-05-22

We have developed an innovative strategy for the formation of angular carbocycles via a gold(I)-catalyzed dehydro Diels-Alder reaction. This transformation provides rapid access to a variety of complex angular cores in excellent diastereoselectivities and high yields. The usefulness of this Au I -catalyzed cycloaddition was further demonstrated by accomplishing a 11-steps total synthesis of (±)-magellanine. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Deeper Insight into the Diels-Alder Reaction through the Activation Strain Model.

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Fernández, Israel; Bickelhaupt, F Matthias

2016-12-06

In this Focus Review, we present the application of the so-called Activation Strain Model of chemical reactivity to the Diels-Alder cycloaddition reaction. To this end, representative recent examples have been selected to illustrate the power of this new computational approach to gain a deeper quantitative understanding of this fundamental process in chemistry. We cover a wide range of issues, such as, the "endo-rule", reactivity trends emerging from systematic variation in the reactants' strain, and cycloaddition reactions involving relevant species in material science, that is, fullerenes, polycyclic aromatic hydrocarbons and nanotubes. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and Computational Studies Demonstrate the Utility of an Intramolecular Styryl Diels-Alder Reaction and Di-t-butylhydroxytoluene Assisted [1,3]-Shift to Construct Anticancer dl-Deoxypodophyllotoxin.

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Saavedra, Diana I; Rencher, Benjamin D; Kwon, Doo-Hyun; Smith, Stacey J; Ess, Daniel H; Andrus, Merritt B

2018-02-16

Deoxypodophyllotoxin is a secondary metabolite lignan possessing potent anticancer activity with potential as a precursor for known anticancer drugs, but its use is limited by scarcity from natural sources. We here report the total synthesis of racemic deoxypodophyllotoxin in seven steps using an intramolecular styryl Diels-Alder reaction strategy uniquely suited to assemble the deoxypodophyllotoxin core. Density functional theory was used to analyze concerted, polar, and singlet-open-shell diradical reaction pathways, which identified a low-energy concerted [4 + 2] Diels-Alder pathway followed by a faster di-t-butylhydroxytoluene assisted [1,3]-formal hydrogen shift.

Extraordinary Mechanism of the Diels-Alder Reaction: Investigation of Stereochemistry, Charge Transfer, Charge Polarization, and Biradicaloid Formation.

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Sexton, Thomas; Kraka, Elfi; Cremer, Dieter

2016-02-25

The Diels-Alder reaction between 1,3-butadiene and ethene is investigated from far-out in the entrance channel to the very last step in the exit channel thus passing two bifurcation points and extending the range of the reaction valley studied with URVA (Unified Reaction Valley Approach) by 300% compared to previous studies. For the first time, the pre- and postchemical steps of the reaction are analyzed at the same level of theory as the actual chemical processes utilizing the path curvature and its decomposition into internal coordinate or curvilinear coordinate components. A first smaller charge transfer to the dienophile facilitates the rotation of gauche butadiene into its cis form. The actual chemical processes are initiated by a second larger charge transfer to the dienophile that facilitates pyramidalization of the reacting carbon centers, bond equalization, and biradicaloid formation of the reactants. The transition state is aromatically stabilized and moved by five path units into the entrance channel in line with the Hammond-Leffler postulate. The pseudorotation of the boat form into the halfchair of cyclohexene is analyzed. Predictions are made for the Diels-Alder reaction based on a 11-phase mechanism obtained by the URVA analysis.

Mono- and polyadducts of C60 with anthracenes by Diels-Alder-reactions

International Nuclear Information System (INIS)

Duarte-Ruiz, A.

2000-09-01

This work describes the synthesis and characterization of seven new mono-adducts of 9-methylanthracene, 9,10-dimethylanthracene, 9-bromoanthracene. 2,3,6,7-tetramethylanthracene, 1-methylanthracene, 2,6-di-tert-butylanthracen, as well as 2-methylanthracene to fullerene C60 in solution at r.t. by means of [4+2] Diels-Alder reactions. It could be shown that the mono-adducts with 9-methylanthracene, 9,10-dimethylanthracene, and 1-methylanthracene form the corresponding antipodal bis-adduct 'trans-1' on heating the solid to 180 o C. Furthermore the functionalization of fullerene C60 anthracene mono-adduct (C60C14H10) with anthracene through [4+2] Diels-Alder reactions was investigated which made it possible to separate and to characterize the five possible bis-adducts ('trans-1', 'trans-2', 'trans-3', 'trans-4', and 'e') that can form when the second anthracene adds either 'trans' to the opposite hemisphere (compared to the first addition of anthracene) or to an equatorial position. An exact identification of the bis-adducts 'trans-2' and 'trans-4' could only be acquired with spectroscopic methods, fortunately the bis-adducts 'trans-4', 'trans-3', and 'e' could also be examined by x-ray, thus all five could be fully characterized. No bis-adducts on the same hemisphere ('cis') were found. UV/VIS-spectra of the bis-adducts opened up the possibility to identify other [4+2] Diels-Alder products in the future. It has been noticed that the eluation sequence of the bis-adducts ('trans-1' before 'trans-2' before 'trans-4' before 'trans-3' before 'e') doesn't strictly correlate with the dipole moments. Furthermore six new tris-adducts ('t4t4t2', 't3t3t3', 't3t3t4', 'et3t2', 'et3t4', and 'eee') and one tetra-adduct ('eeet3') were separated and characterized. The tris-adduct 't3t3t3' was additionally characterized by x-ray which showed that the crystal contains only one enatiomer. All bis- and tris-adducts form the antipodal bis-adduct 'trans-1' on heating to 180 o C for 10 min

Asymmetric Diels-Alder Reaction of α-Substituted and β,β-Disubstituted α,β-Enals via Diarylprolinol Silyl Ether for the Construction of All-Carbon Quaternary Stereocenters.

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Hayashi, Yujiro; Bondzic, Bojan P; Yamazaki, Tatsuya; Gupta, Yogesh; Ogasawara, Shin; Taniguchi, Tohru; Monde, Kenji

2016-10-24

The asymmetric Diels-Alder reaction of α-substituted acrolein proceeds in the presence of the trifluoroacetic acid salt of trifluoromethyl-substituted diarylprolinol silyl ether to afford the exo-isomer with both excellent diastereoselectivity and high enantioselectivity. In the Diels-Alder reaction of a β,β-disubstituted α,β-unsaturated aldehyde, good exo-selectivity and excellent enantioselectivity was obtained when the perchloric acid salt of the bulky triisopropyl silyl ether of trifluoromethyl substituted diarylprolinol was employed as an organocatalyst in the presence of water. In both cases, all-carbon quaternary stereocenters are constructed enantioselectively. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

An intermolecular Diels-Alder cycloaddition under various condition between 1,3-cyclohexadiene and 7-oxabicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylate

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Özgür Yılmaz

2017-10-01

Full Text Available The reaction between 1,3-cyclohexadiene and dimethyl 7-oxabicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylate both without a catalyst and with different catalysts, in both atmospheric and at high pressure, over 20 days were studied. At the end of the reactions, different products (retro Diels-Alder addition product 5 and Diels-Alder addition product 6 were obtained in different yields. When we look at the percentage of the addition product, it is observed that the yield of reaction at high pressure in water is the highest. All structures of these products were characterized by 1H-NMR, 13C-NMR, MS, and IR spectroscopy.

Stable elements and radionuclides in shoreline alder stands at Olkiluoto in 2005

International Nuclear Information System (INIS)

Roivainen, P.

2006-08-01

In Finland, the final disposal of spent nuclear fuel from Finnish nuclear power plants is to take place in a repository, which will be built in Olkiluoto bedrock. According to the current plans, operation of the facility will start in 2020. Before this, a safety case has to be drawn up to substantiate the safety of the final disposal solution. The drawing up of the safety case also involves an assessment of impact on organisms other than human. Several radionuclides have a stable chemical analogue. Chemical analogues often display similar behaviour in the forest ecosystem. For this reason, information about radionuclides can also be obtained by studying stable elements. The purpose of this thesis was to study the migration of elements, radionuclides in particular, in the food webs of the Olkiluoto forest ecosystem. The objective was to produce concentration ratios between the various sub-components of the forest ecosystem. These ratios can be utilised in modelling. Three alder stands on the shores of Olkiluoto were used as monitoring plots. Littoral alder stands are an important biotope in terms of a recipient of the potential radionuclide contamination from the repository. Yet, research on littoral alder stands has so far been quite limited. From all the monitoring plots, a sample was taken of humus, mineral soil, understorey, plant roots and forest litter. Small mammals and earthworms were also to be caught from the monitoring plots, but no earthworms could be caught in any of the areas. All the collected samples were analysed for element concentrations using the ICP-AES method. Soil and plant samples were also analysed with a gamma spectrometer for activity concentrations of gamma active radionuclides. Activity concentrations of Cs-137 and K-40 could be determined in all soil and plant samples. The highest activity concentration of Cs-137 was found in humus, and the lowest in mineral soil. The activity concentration of K-40 was at its highest in mineral soil and

A Tunable and Enantioselective Hetero-Diels-Alder Reaction Provides Access to Distinct Piperidinoyl Spirooxindoles.

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Jayakumar, Samydurai; Louven, Kathrin; Strohmann, Carsten; Kumar, Kamal

2017-12-11

The active complexes of chiral N,N'-dioxide ligands with dysprosium and magnesium salts catalyze the hetero-Diels-Alder reaction between 2-aza-3-silyloxy-butadienes and alkylidene oxindoles to selectively form 3,3'- and 3,4'-piperidinoyl spirooxindoles, respectively, in very high yields and with excellent enantioselectivities. The exo-selective asymmetric cycloaddition successfully regaled the construction of sp 3 -rich and highly substituted natural-product-based spirooxindoles supporting many chiral centers, including contiguous all-carbon quaternary centers. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Studies toward the synthesis of palhinine lycopodium alkaloids: a Morita-Baylis-Hillman/intramolecular Diels-Alder approach.

Science.gov (United States)

Sizemore, Nicholas; Rychnovsky, Scott D

2014-02-07

A synthetic route to the isotwistane core of palhinine lycopodium alkaloids is described. A Morita-Baylis-Hillman/intramolecular Diels-Alder (IMDA) strategy sets the vicinal all-carbon quaternary centers present in this family of natural products. The regioselectivity of the IMDA reaction is dictated by the conditions employed for silyl enol ether formation, with one set of conditions providing the core of cardionine and alternate conditions generating the desired isotwistane core of isopalhinine.

Theoretical Study on Regioselectivity of the Diels-Alder Reaction between 1,8-Dichloroanthracene and Acrolein.

Science.gov (United States)

Sultan, Mujeeb A; Karama, Usama; Almansour, Abdulrahman I; Soliman, Saied M

2016-09-23

A theoretical study of the regioselectivity of the Diels-Alder reaction between 1,8-dichloroanthracene and acrolein is performed using DFT at the B3LYP/6-31G(d,p) level of theory. The FMO analysis, global and local reactivity indices confirmed the reported experimental results. Potential energy surface analysis showed that the cycloadditions (CAs) favor the formation of the anti product. These results are in good agreement with the reported results obtained experimentally where the anti is the major product.

Bicyclic Guanidine Catalyzed Asymmetric Tandem Isomerization Intramolecular-Diels-Alder Reaction: The First Catalytic Enantioselective Total Synthesis of (+)-alpha-Yohimbine.

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Feng, Wei; Jiang, Danfeng; Kee, Choon-Wee; Liu, Hongjun; Tan, Choon-Hong

2016-02-04

Hydroisoquinoline derivatives were prepared in moderate to good enantioselectivities via a bicyclic guanidine-catalyzed tandem isomerization intramolecular-Diels-Alder (IMDA) reaction of alkynes. With this synthetic method, the first enantioselective synthesis of (+)-alpha-yohimbine was completed in 9 steps from the IMDA products. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

No evidence found for Diels-Alder reaction products in soybean oil oxidized at the frying temperature by NMR study

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It has been generally accepted that the Diels-Alder reaction mechanism is one of the major reaction mechanisms to produce dimers and polymers during heating process of vegetable oil. Soybean oil oxidized at 180 °C for 24 hrs with 1.45 surface area-to-volume ratio showed 36.1% polymer peak area in g...

Reactivity of Single-Walled Carbon Nanotubes in the Diels-Alder Cycloaddition Reaction: Distortion-Interaction Analysis along the Reaction Pathway.

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Li, Yingzi; Osuna, Sílvia; Garcia-Borràs, Marc; Qi, Xiaotian; Liu, Song; Houk, Kendall N; Lan, Yu

2016-08-26

Diels-Alder cycloaddition is one of the most powerful tools for the functionalization of single-walled carbon nanotubes (SWCNTs). Density functional theory at the B3-LYP level of theory has been used to investigate the reactivity of different-diameter SWCNTs (4-9,5) in Diels-Alder reactions with 1,3-butadiene; the reactivity was found to decrease with increasing SWCNT diameter. Distortion/interaction analysis along the whole reaction pathway was found to be a better way to explore the reactivity of this type of reaction. The difference in interaction energy along the reaction pathway is larger than that of the corresponding distortion energy. However, the distortion energy plots for these reactions show the same trend. Therefore, the formation of the transition state can be determined from the interaction energy. A lower interaction energy leads to an earlier transition state, which indicates a lower activation energy. The computational results also indicate that the original distortion of the SWCNTs leads to an increase in the reactivity of the SWCNTs. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Highly enantioselective access to cannabinoid-type tricyles by organocatalytic Diels–Alder reactions

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Stefan Bräse

2012-08-01

Full Text Available After prosperous domino reactions towards benzopyrans, the products were used as the starting material in Lewis acid catalyzed and organocatalytic Diels–Alder reactions to build up a tricyclic system. Herein, an asymmetric induction up to 96% enantiomeric excess was obtained by the use of imidazolidinone catalysts. This approach can be utilized to construct the tricyclic system in numerous natural products, in particular the scaffold of tetrahydrocannabinol (THC being the most representative one. Compared with other published methods, condensation with a preexisting cyclohexane moiety in the precursor is needed to gain the heterogenic tricycle systems, whereas we present a novel strategy towards cannabinoid derivatives based on a flexible modular synthesis.

Fast Hetero-Diels-Alder Reactions Using 4-Phenyl-1,2,4-Triazoline-3,5-Dione (PTAD) as the Dienophile

Science.gov (United States)

Celius, Tevye C.

2010-01-01

A hetero-Diels-Alder reaction that proceeds rapidly and only requires a simple filtration to purify the product is presented. The dienophile, 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD), is prepared by the heterogeneous oxidation of 4-phenylurazole by the bromenium ion, Br[superscript +], generated in situ by the oxidation of potassium bromide by…

Petasis/Diels-Alder/Cyclization Cascade Reactions for the Generation of Scaffolds with Multiple Stereogenic Centers and Orthogonal Handles for Library Production

DEFF Research Database (Denmark)

Flagstad, Thomas; Azevedo, Carlos M. G.; Min, Geanna

2018-01-01

A new effective strategy for the synthesis of sp3‐rich small molecules for library production is presented. The key steps to generate complexity highlight Petasis 3‐component reaction followed by an intramolecular Diels‐Alder and cyclization to generate a densely enriched tricyclic or tetracyclic...

Effects of elevated CO2 on litter chemistry and subsequent invertebrate detritivore feeding responses.

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Matthew W Dray

Full Text Available Elevated atmospheric CO2 can change foliar tissue chemistry. This alters leaf litter palatability to macroinvertebrate detritivores with consequences for decomposition, nutrient turnover, and food-web structure. Currently there is no consensus on the link between CO2 enrichment, litter chemistry, and macroinvertebrate-mediated leaf decomposition. To identify any unifying mechanisms, we presented eight invertebrate species from aquatic and terrestrial ecosystems with litter from Alnus glutinosa (common alder or Betula pendula (silver birch trees propagated under ambient (380 ppm or elevated (ambient +200 ppm CO2 concentrations. Alder litter was largely unaffected by CO2 enrichment, but birch litter from leaves grown under elevated CO2 had reduced nitrogen concentrations and greater C/N ratios. Invertebrates were provided individually with either (i two litter discs, one of each CO2 treatment ('choice', or (ii one litter disc of each CO2 treatment alone ('no-choice'. Consumption was recorded. Only Odontocerum albicorne showed a feeding preference in the choice test, consuming more ambient- than elevated-CO2 birch litter. Species' responses to alder were highly idiosyncratic in the no-choice test: Gammarus pulex and O. albicorne consumed more elevated-CO2 than ambient-CO2 litter, indicating compensatory feeding, while Oniscus asellus consumed more of the ambient-CO2 litter. No species responded to CO2 treatment when fed birch litter. Overall, these results show how elevated atmospheric CO2 can alter litter chemistry, affecting invertebrate feeding behaviour in species-specific ways. The data highlight the need for greater species-level information when predicting changes to detrital processing-a key ecosystem function-under atmospheric change.

A Catalyst-Enabled Diastereodivergent Aza-Diels-Alder Reaction: Complementarity of N-Heterocyclic Carbenes and Chiral Amines.

Science.gov (United States)

Rong, Zi-Qiang; Wang, Min; Chow, Chi Hao Eugene; Zhao, Yu

2016-07-04

Highly efficient and diastereodivergent aza-Diels-Alder reactions have been developed to access either diastereomeric series of benzofuran-fused δ-lactams and dihydropyridines in nearly perfect stereoselectivity (d.r. >20:1, >99 % ee for all examples). The complementarity of N-heterocyclic carbene and chiral amine as the catalyst was demonstrated for the first time, together with an excellent level of catalytic efficiency (1 mol % loading). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of stimuli-responsive chitosan-based hydrogels by Diels-Alder cross-linking `click´ reaction as potential carriers for drug administration.

Science.gov (United States)

Guaresti, O; García-Astrain, C; Aguirresarobe, R H; Eceiza, A; Gabilondo, N

2018-03-01

Stimuli-responsive chitosan-based hydrogels for biomedical applications using the Diels-Alder reaction were prepared. Furan modified chitosan (Cs-Fu) was cross-linked with polyetheramine derived bismaleimide at different equivalent ratios in order to determine the effect in the swelling and release properties on the final CsFu:BMI hydrogels. The Diels Alder cross-linking reaction was monitored by UV-vis spectroscopy and rheological measurements. Both the sol-gel transition value and the final storage modulus for the different formulations were similar and close to 40 min and 400 Pa, respectively. On the contrary, the swelling degree was found to be strongly dependent on the amount of bismaleimide, mainly in acidic medium, where the increased cross-linking reduced the swelling value in 25%, but maintaining the sustained drug release in the simulated gastrointestinal environment. Our study suggested that these DA-cross-linked chitosan hydrogels could be potential carriers for targeted drug administration. Copyright © 2017 Elsevier Ltd. All rights reserved.

A theoretical investigation on the regioselectivity of the intramolecular hetero Diels-Alder and 1,3-dipolar cycloaddition of 2-vinyloxybenzaldehyde derivatives

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Hamzehloueian Mahshid

2014-01-01

Full Text Available The present study reports a systematic computational analysis of the two possible pathways, fused and bridged, for an intramolecular hetero Diels-Alder (IMHDA and an intramolecular 1,3-dipolar cycloaddition (IMDCA of 2-vinyloxybenzaldehyde derivatives. The potential energy surface analysis for both reactions is in agreement with experimental observations. The activation energies associated with the two regioisomeric channels in IMHDA reaction show that the bridged product is favored, although in IMDCA, the most stable TS results the fused product. The global electronic properties of fragments within each molecule were studied to discuss the reactivity patterns and charge transfer direction in the intramolecular processes. The asynchronicity of the bond formation and aromaticity of the optimized TSs in the Diels-Alder reaction as well as cycloaddition reaction were evaluated. Finally, 1H NMR chemical shifts of the possible regioisomers have been calculated using the GIAO method which of the most stable products are in agreement with the experimental data in the both reaction.

Theoretical Study on Regioselectivity of the Diels-Alder Reaction between 1,8-Dichloroanthracene and Acrolein

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Mujeeb A. Sultan

2016-09-01

Full Text Available A theoretical study of the regioselectivity of the Diels-Alder reaction between 1,8-dichloroanthracene and acrolein is performed using DFT at the B3LYP/6-31G(d,p level of theory. The FMO analysis, global and local reactivity indices confirmed the reported experimental results. Potential energy surface analysis showed that the cycloadditions (CAs favor the formation of the anti product. These results are in good agreement with the reported results obtained experimentally where the anti is the major product.

Stereo- and regioselectivity of the hetero-Diels-Alder reaction of nitroso derivatives with conjugated dienes.

Science.gov (United States)

Brulíková, Lucie; Harrison, Aidan; Miller, Marvin J; Hlaváč, Jan

2016-01-01

The hetero-Diels-Alder reaction between a nitroso dienophile and a conjugated diene to give the 3,6-dihydro-2 H -1,2-oxazine scaffold is useful for the synthesis of many biologically interesting molecules due to the diverse opportunities created by subsequent transformations of the resulting 1,2-oxazine ring. This review discusses the rationale for the observed regio- and stereoselectivity and the methods developed in recent years used to control and improve the stereo- and regioselectivity for the synthesis of 1,2-oxazine scaffolds.

Spectacular Rate Enhancement of the Diels-Alder Reaction at the Ionic Liquid/n-Hexane Interface.

Science.gov (United States)

Beniwal, Vijay; Manna, Arpan; Kumar, Anil

2016-07-04

The use of the ionic liquid/n-hexane interface as a new class of reaction medium for the Diels-Alder reaction gives large rate enhancements of the order of 10(6) to 10(8) times and high stereoselectivity, as compared to homogeneous media. The rate enhancement is attributed to the H-bonding abilities and polarities of the ionic liquids, whereas the hydrophobicity of ionic liquids was considered to be the factor in controlling stereoselectivity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A computational study of the Diels Alder reactions involving acenes: reactivity and aromaticity

Science.gov (United States)

Cheng, Mei-Fun; Li, Wai-Kee

2003-01-01

Ab initio and DFT methods have been used to study the Diels-Alder reactivity and the aromaticity of four linear acenes, namely, naphthalene, anthracene, tetracene and pentacene. In total, eight additional pathways between ethylene and four acenes have been studied and all of them are concerted and exothermic reactions. It is found that the most reactive sites on the acenes are the center ring's meso-carbons. Also, reactivity decreases along the series pentacene > tetracene > anthracene > naphthalene. In addition, the NICS results indicate that the most reactive rings in the acenes are those with the highest aromaticity. These results are consistent with those of other theoretical studies and experiments.

Asymmetric NHC-catalyzed aza-Diels-Alder reactions: Highly enantioselective route to α-amino acid derivatives and DFT calculations

KAUST Repository

Yang, Limin

2014-08-01

A facile N-heterocyclic carbene catalytic enantioselective aza-Diels-Alder reaction of oxodiazenes with α-chloroaldehydes as dienophile precursors is reported, with excellent enantioselectivity (ee > 99%) and excellent yield (up to 93%). DFT study showed that cis-TSa, formed from a top face approach of oxodiazene to cis-IIa, is the most favorable transition state and is consistent with the experimental observations. © 2014 American Chemical Society.

A hetero retro Diels-Alder reaction in aqueous solution : A dramatic water-induced increase of the equilibrium constant and inhibition of cycloreversion

NARCIS (Netherlands)

Wijnen, J.W; Engberts, J.B.F.N.

The adduct of the Diels-Alder reaction of nitrosobenzene with cyclopentadiene is not stable in solution. The equilibrium constant for the reaction depends strongly on the medium and water induces a spectacular shift to the adduct. Comparison with the bimolecular addition of nitrosobenzene to

Microwave- assisted solvent-free Diels-Alder reaction – a fast and simple route to various 5,6-substituted norbornenes and polychlorinated norbornenes

Czech Academy of Sciences Publication Activity Database

Dejmek, Milan; Hřebabecký, Hubert; Šála, Michal; Dračínský, Martin; Nencka, Radim

-, č. 24 (2011), s. 4077-4083 ISSN 0039-7881 R&D Projects: GA MŠk 1M0508 Institutional research plan: CEZ:AV0Z40550506 Keywords : Diels - Alder reaction * polychlorinated norbornanes * norbornene Subject RIV: CC - Organic Chemistry Impact factor: 2.466, year: 2011

Design and synthesis of polycyclic sulfones via Diels-Alder reaction and ring-rearrangement metathesis as key steps.

Science.gov (United States)

Kotha, Sambasivarao; Gunta, Rama

2015-01-01

Here, we describe a new and simple synthetic strategy to various polycyclic sulfones via Diels-Alder reaction and ring-rearrangement metathesis (RRM) as the key steps. This approach delivers tri- and tetracyclic sulfones with six (n = 1), seven (n = 2) or eight-membered (n = 3) fused-ring systems containing trans-ring junctions unlike the conventional all cis-ring junctions generally obtained during the RRM sequence. Interestingly the starting materials used are simple and commercially available.

Stereo- and regioselectivity of the hetero-Diels–Alder reaction of nitroso derivatives with conjugated dienes

Directory of Open Access Journals (Sweden)

Lucie Brulíková

2016-09-01

Full Text Available The hetero-Diels–Alder reaction between a nitroso dienophile and a conjugated diene to give the 3,6-dihydro-2H-1,2-oxazine scaffold is useful for the synthesis of many biologically interesting molecules due to the diverse opportunities created by subsequent transformations of the resulting 1,2-oxazine ring. This review discusses the rationale for the observed regio- and stereoselectivity and the methods developed in recent years used to control and improve the stereo- and regioselectivity for the synthesis of 1,2-oxazine scaffolds.

Studies on the interactions of 5-R-3-(2-pyridyl)-1,2,4-triazines with arynes: inverse demand aza-Diels-Alder reaction versus aryne-mediated domino process.

Science.gov (United States)

Kopchuk, Dmitry S; Nikonov, Igor L; Khasanov, Albert F; Giri, Kousik; Santra, Sougata; Kovalev, Igor S; Nosova, Emiliya V; Gundala, Sravya; Venkatapuram, Padmavathi; Zyryanov, Grigory V; Majee, Adinath; Chupakhin, Oleg N

2018-05-02

The interactions between substituted 5-R-3-(pyridyl-2)-1,2,4-triazines with in situ generated substituted aryne intermediates have been studied. The reaction afforded either inverse demand (ID) aza-Diels-Alder products or 1,2,4-triazine ring rearrangement (domino) products as major ones depending on the nature of both the substituents at the C5 position of the 1,2,4-triazine core or in the aryne moiety. The structures of the key products were confirmed based on X-ray data. Based on the density functional theoretical (DFT) studies of the Diels-Alder transition state geometries, the influence of the nature of arynes on the direction of the 1,2,4-triazine transformation has been proposed.

Integration of Computational and Preparative Techniques to Demonstrate Physical Organic Concepts in Synthetic Organic Chemistry: An Example Using Diels-Alder Reaction

Science.gov (United States)

Palmer, David R. J.

2004-01-01

The Diels-Alder reaction is used as an example for showing the integration of computational and preparative techniques, which help in demonstrating the physical organic concepts in synthetic organic chemistry. These experiments show that the students should not accept the computational results without questioning them and in many Diels-Alder…

The Synthesis of "N"-Benzyl-2-Azanorbornene via Aqueous Hetero Diels-Alder Reaction: An Undergraduate Project in Organic Synthesis and Structural Analysis

Science.gov (United States)

Sauvage, Xavier; Delaude, Lionel

2008-01-01

The synthesis of "N"-benzyl-2-azanorbornene via aqueous hetero Diels-Alder reaction of cyclopentadiene and benzyliminium chloride formed in situ from benzylamine hydrochloride and formaldehyde is described. Characterization of the product was achieved by IR and NMR spectroscopies. The spectral data acquired are thoroughly discussed. Numerous…

Regioselectivity of Sc2C2@C3v(8)-C82: Role of the Sumanene-Type Hexagon in Diels-Alder Reaction.

Science.gov (United States)

Zhao, Pei; Zhao, Xiang; Ehara, Masahiro

2016-09-16

Recently, several experiments have demonstrated high chemical reactivity of the sumanene-type hexagon in Sc2C2@C82. To further uncover its reactivity, the Diels-Alder reaction to all the nonequivalent C-C bonds of C82 and Sc2C2@C82 has been investigated by density functional theory calculations. For the free fullerene, the [5,6] bond 7 is the thermodynamically most favored, whereas the addition on the [6,6] bond 3 has the lowest activation energy. Diels-Alder reaction has no preference for addition sites in the sumanene-type hexagon. However, in the case of the endohedral fullerene, the [6,6] bond 19 in the special hexagon becomes the most reactive site according to both kinetic and thermodynamic considerations. Further analyses reveal that bond 19 in Sc2C2@C82 exhibits the shortest bond length and third largest π-orbital axis vector. In addition, the LUMOs of bond 19 are also symmetry-allowed to interact with butadiene.

On the Diels-Alder approach to solely biomass-derived polyethylene terephthalate (PET): conversion of 2,5-dimethylfuran and acrolein into p-xylene.

Science.gov (United States)

Shiramizu, Mika; Toste, F Dean

2011-10-24

Polyethylene terephthalate (PET) is a polymeric material with high global demand. Conventionally, PET is produced from fossil-fuel-based materials. Herein, we explored the feasibility of a sustainable method for PET production by using solely bio-renewable resources. Specifically, 2,5-dimethylfuran (derived from lignocellulosic biomass through 5-(hydroxymethyl)furfural) and acrolein (produced from glycerol, a side product of biodiesel production) were converted into the key intermediate p-xylene (a precursor of terephthalic acid). This synthesis consists of a sequential Diels-Alder reaction, oxidation, dehydration, and decarboxylation. In particular, the pivotal first step, the Diels-Alder reaction, was studied in detail to provide useful kinetic and thermodynamic data. Although it was found that this reaction requires low temperature to proceed efficiently, which presents a limitation on economic feasibility on an industrial scale, the concept was realized and bio-derived p-xylene was obtained in 34% overall yield over four steps. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Asymmetric Diels–Alder reaction with >C=P– functionality of the 2-phosphaindolizine-η1-P-aluminium(O-menthoxy dichloride complex: experimental and theoretical results

Directory of Open Access Journals (Sweden)

Rajendra K. Jangid

2013-02-01

Full Text Available The Diels–Alder reaction of the 2-phosphaindolizine-η1-P-aluminium(O-menthoxy dichloride complex with dimethylbutadiene was investigated experimentally and computationally. The >C=P– functionality of the complex reacts with 2,3-dimethylbutadiene with complete diastereoselectivity to afford [2 + 4] cycloadducts. Calculation of the model substrate, 3-methoxycarbonyl-1-methyl-2-phosphaindolizine-P-aluminium(O-menthoxy dichloride (7a, at the DFT (B3LYP/6-31+G* level reveals that the O-menthoxy moiety blocks the Re face of the >C=P– functionality, due to which the activation barrier of the Diels–Alder reaction of 7a with 1,3-butadiene, involving its attack from the Si face, is lower. It is found that in this case, the exo approach of the diene is slightly preferred over the endo approach.

Green Transformational Leadership and Green Performance: The Mediation Effects of Green Mindfulness and Green Self-Efficacy

Directory of Open Access Journals (Sweden)

Yu-Shan Chen

2014-09-01

Full Text Available No prior literature explores the influence of green transformational leadership on green performance, thus, this study develops a novel research framework to fill the research gap. This study investigates the influence of green transformational leadership on green performance and discusses the mediation effects of green mindfulness and green self-efficacy by means of structural equation modeling (SEM. The results indicate that green transformational leadership positively influences green mindfulness, green self-efficacy, and green performance. Moreover, this study demonstrates that the positive relationship between green transformational leadership and green performance is partially mediated by the two mediators: green mindfulness and green self-efficacy. It means that green transformational leadership can not only directly affect green performance positively but also indirectly affect it positively through green mindfulness and green self-efficacy. Therefore, firms need to raise their green transformational leadership, green mindfulness, and green self-efficacy to increase their green performance.

Tandem cross enyne metathesis (CEYM)-intramolecular Diels-Alder reaction (IMDAR). An easy entry to linear bicyclic scaffolds.

Science.gov (United States)

Miró, Javier; Sánchez-Roselló, María; Sanz, Álvaro; Rabasa, Fernando; Del Pozo, Carlos; Fustero, Santos

2015-01-01

A new tandem cross enyne metathesis (CEYM)-intramolecular Diels-Alder reaction (IMDAR) has been carried out. It involves conjugated ketones, esters or amides bearing a remote olefin and aromatic alkynes as the starting materials. The overall process enables the preparation of a small family of linear bicyclic scaffolds in a very simple manner with moderate to good levels of diastereoselectivity. This methodology constitutes one of the few examples that employ olefins differently than ethylene in tandem CEYM-IMDAR protocols.

Assessment of abandoned agricultural land resource for bio-energy production in Estonia

Energy Technology Data Exchange (ETDEWEB)

Kukk, Liia; Astover, Alar; Roostalu, Hugo; Suuster, Elsa; Noormets, Merrit; Sepp, Kalev (Estonian Univ. of Life Sciences, Inst. of Agricultural and Environmental Sciences, Tartu (Estonia)); Muiste, Peeter (Estonian Univ. of Life Sciences, Inst. of Forestry and Rural Engineering, Tartu (Estonia))

2010-03-15

The current study locates and quantifies abandoned agricultural areas using the Geographic Information System (GIS) and evaluates the suitability of abandoned fields for bio-energy production in Tartumaa (Tartu County) in Estonia. Soils of abandoned areas are generally of low quality and thereby limited suitability for crop production; as a result soil-crop suitability analyses could form the basis of knowledge-based bio-energy planning. The study estimated suitable areas for bio-energy production using willow (Salix sp), grey alder [Alnus incana (L.) Moench], hybrid aspen (Populus tremuloides Michx.Populus tremula L.), reed canary grass (Phalaris arundinacea L.), and Caucasian goat's rue (Galega orientalis Lam.) in separate plantations. A combined land-use strategy is also presented as these crops are partially suitable to the same areas. Reed canary grass and grey alder have the highest energy potentials and each would re-use more than 80% of the available abandoned agricultural land. Energy grasses and short-rotation forestry in combined land-use strategy represents the opportunity of covering approximately a quarter of county's annual energy demand. The study estimates only agronomic potential, so further bio-energy analysis should take into account technical and economic limitations. Developed framework supports knowledge-based decision-making processes from field to regional scale to achieve sustainable bio-energy production

Tyrosine-lipid peroxide adducts from radical termination: para coupling and intramolecular Diels-Alder cyclization.

Science.gov (United States)

Shchepin, Roman; Möller, Matias N; Kim, Hye-young H; Hatch, Duane M; Bartesaghi, Silvina; Kalyanaraman, Balaraman; Radi, Rafael; Porter, Ned A

2010-12-15

Free radical co-oxidation of polyunsaturated lipids with tyrosine or phenolic analogues of tyrosine gave rise to lipid peroxide-tyrosine (phenol) adducts in both aqueous micellar and organic solutions. The novel adducts were isolated and characterized by 1D and 2D NMR spectroscopy as well as by mass spectrometry (MS). The spectral data suggest that the polyunsaturated lipid peroxyl radicals give stable peroxide coupling products exclusively at the para position of the tyrosyl (phenoxy) radicals. These adducts have characteristic (13)C chemical shifts at 185 ppm due to the cross-conjugated carbonyl of the phenol-derived cyclohexadienone. The primary peroxide adducts subsequently undergo intramolecular Diels-Alder (IMDA) cyclization, affording a number of diastereomeric tricyclic adducts that have characteristic carbonyl (13)C chemical shifts at ~198 ppm. All of the NMR HMBC and HSQC correlations support the structure assignments of the primary and Diels-Alder adducts, as does MS collision-induced dissociation data. Kinetic rate constants and activation parameters for the IMDA reaction were determined, and the primary adducts were reduced with cuprous ion to give a phenol-derived 4-hydroxycyclohexa-2,5-dienone. No products from adduction of peroxyls at the phenolic ortho position were found in either the primary or cuprous reduction product mixtures. These studies provide a framework for understanding the nature of lipid-protein adducts formed by peroxyl-tyrosyl radical-radical termination processes. Coupling of lipid peroxyl radicals with tyrosyl radicals leads to cyclohexenone and cyclohexadienone adducts, which are of interest in and of themselves since, as electrophiles, they are likely targets for protein nucleophiles. One consequence of lipid peroxyl reactions with tyrosyls may therefore be protein-protein cross-links via interprotein Michael adducts.

Insight into the informational-structure behavior of the Diels-Alder reaction of cyclopentadiene and maleic anhydride.

Science.gov (United States)

Molina-Espíritu, Moyocoyani; Esquivel, Rodolfo O; Kohout, Miroslav; Angulo, Juan Carlos; Dobado, José A; Dehesa, Jesús S; LópezRosa, Sheila; Soriano-Correa, Catalina

2014-08-01

The course of the Diels-Alder reactions of cyclopentadiene and maleic anhydride were studied. Two reaction paths were modelled: endo- and exo-selective paths. All structures within the transient region were characterized and analyzed by means of geometrical descriptors, physicochemical parameters and information-theoretical measures in order to observe the linkage between chemical behavior and the carriage of information. We have shown that the information-theoretical characterization of the chemical course of the reaction is in complete agreement with its phenomenological behavior in passing from reactants to products. In addition, we were able to detect the main differences between the two reaction mechanisms. This type of informational analysis serves to provide tools to help understand the chemical reactivity of the two simplest Diels-Alder reactions, which permits the establishment of a connection between the quantum changes that molecular systems exert along reaction coordinates and standard physicochemical phenomenology. In the present study, we have shown that every reaction stage has a family of subsequent structures that are characterized not solely by their phenomenological behavior but also by informational properties of their electronic density distribution (localizability, order, uniformity). Moreover, we were able to describe the main differences between endo-adduct and exo-adduct pathways. With the advent of new experimental techniques, it is in principle possible to observe the structural changes in the transient regions of chemical reactions. Indeed, through this work we have provided the theoretical concepts needed to unveil the concurrent processes associated with chemical reactions.

Molecular Design of a Chiral Brønsted Acid with Two Different Acidic Sites: Regio-, Diastereo-, and Enantioselective Hetero-Diels-Alder Reaction of Azopyridinecarboxylate with Amidodienes Catalyzed by Chiral Carboxylic Acid-Monophosphoric Acid.

Science.gov (United States)

Momiyama, Norie; Tabuse, Hideaki; Noda, Hirofumi; Yamanaka, Masahiro; Fujinami, Takeshi; Yamanishi, Katsunori; Izumiseki, Atsuto; Funayama, Kosuke; Egawa, Fuyuki; Okada, Shino; Adachi, Hiroaki; Terada, Masahiro

2016-09-07

A chiral Brønsted acid containing two different acidic sites, chiral carboxylic acid-monophosphoric acid 1a, was designed to be a new and effective concept in catalytic asymmetric hetero-Diels-Alder reactions of azopyridinecarboxylate with amidodienes. The multipoint hydrogen-bonding interactions among the carboxylic acid, monophosphoric acid, azopyridinecarboxylate, and amidodiene achieved high catalytic and chiral efficiency, producing substituted 1,2,3,6-tetrahydropyridazines with excellent stereocontrol in a single step. This constitutes the first example of regio-, diastereo-, and enantioselective azo-hetero-Diels-Alder reactions by chiral Brønsted acid catalysis.

Ancient plant remains with special reference to buckthorn, Frangula alnus Mill., pyrenes from Dascyleum, Balıkesir, NW Turkey

Directory of Open Access Journals (Sweden)

Emel Oybak Dönmez

2016-12-01

Full Text Available Carbonized plant remains recovered from the ancient city Dascyleum (Daskyleion in the province of Balıkesir in northwestern Turkey provide an outline of several phases of plant use in archaic, Hellenistic, and medieval times. At the study site, various crop plant remains of Near Eastern agriculture, including cereals (barley, Hordeum vulgare L. and bread/durum/rivet wheat, Triticum aestivum L. / T. durum Desf. / T. turgidum L. and pulses [bitter vetch, Vicia ervilia (L. Willd.; grass pea, Lathyrus sativus L. / L. cicera L.; fava bean, V. faba L.; and chickpea, Cicer arietinum L.] were found. Drupaceous fruits and pyrenes of buckthorn (Frangula alnus Mill. were also found, probably representing dyes and/or medicines used by the inhabitants of the mound. Archaeometrical analyses of the ancient buckthorn pyrenes by high performance liquid chromatography with photodiode array detector (HPLC-PDA provide chemical evidence for traces of ancient mordants remaining until the present day. Some of the pulse seed remains retrieved from the medieval layers at the study site were found to have been infested by bruchid beetles (Bruchidae.

Tandem cross enyne metathesis (CEYM–intramolecular Diels–Alder reaction (IMDAR. An easy entry to linear bicyclic scaffolds

Directory of Open Access Journals (Sweden)

Javier Miró

2015-08-01

Full Text Available A new tandem cross enyne metathesis (CEYM–intramolecular Diels–Alder reaction (IMDAR has been carried out. It involves conjugated ketones, esters or amides bearing a remote olefin and aromatic alkynes as the starting materials. The overall process enables the preparation of a small family of linear bicyclic scaffolds in a very simple manner with moderate to good levels of diastereoselectivity. This methodology constitutes one of the few examples that employ olefins differently than ethylene in tandem CEYM–IMDAR protocols.

An Inverse Electron Demand Azo-Diels-Alder Reaction of o-Quinone Methides and Imino Ethers: Synthesis of Benzocondensed 1,3-Oxazines.

Science.gov (United States)

Osipov, Dmitry V; Osyanin, Vitaly A; Khaysanova, Guzel' D; Masterova, Elvira R; Krasnikov, Pavel E; Klimochkin, Yuri N

2018-04-20

We have studied the reactions of o-quinone methide precursors with imino ethers. The reaction provides a versatile route to substituted 1,3-benzoxazines. The proposed reaction mechanism involves the generation of the o-quinone methide intermediates, imino-Diels-Alder reaction, and elimination. This cascade process is a rare example of the participation of imino ethers as dienophiles.

Permanent vegetation quadrats on Olkiluoto island. Establishment and results from the first inventory

Energy Technology Data Exchange (ETDEWEB)

Huhta, A.P.; Korpela, L. [Finnish Forest Research Institute, Helsinki (Finland)

2006-05-15

This report describes in detail the vegetation quadrats established inside the permanent, follow-up sample plots (Forest Extensive High-level monitoring plots, FEH) on Olkiluoto Island. During summer 2005 a total of 94 sample plots (a 30 m{sup 2}), each containing eight quadrats (a 1m{sup 2}), were investigated. The total number of sampled quadrats was 752. Seventy of the 94 plots represent coniferous stands: 57 Norway spruce-dominated and 13 Scots pine-dominated stands. Ten of the plots represent deciduous, birch-dominated (Betula spp.) stands, 7 plots common alder-dominated (Alnus glutinosa) stands, and seven plots are mires. The majority of the coniferous tree stands were growing on sites representing various succession stages of the Myrtillus, Vaccinium-Myrtillus and Deschampsia-Myrtillus forest site types. The pine-dominated stands growing on exposed bedrock clearly differed from the other coniferous stands: the vegetation was characterised by the Cladina, Calluna-Cladina and Empetrum-Vaccinium vitis-idaea/Vaccinium Myrtillus forest site types. The deciduous stands were characterized by tall grasses, especially Calamagrostis epigejos, C. purpurea and Deschampsia flexuosa. The vegetation of the deciduous stands dominated by common alder represented grove-like sites and seashore groves. Typical species for mires included Calamagrostis purpurea, Calla palustris, Equisetum sylvaticum, and especially white mosses (Sphagnum spp.). A total of 184 vascular plant species were found growing within the quadrats. Due to the high number of quadrats in these forests, the spruce stands had the highest total number of species, but the birch and alder-dominated forests had the highest average number of species per quadrat. This basic inventory of the permanent vegetation quadrats on Olkiluoto Island provides a sound starting point for future vegetation surveys. Guidelines for future inventories and supplementary sampling are given in the discussion part of this report. (orig.)

Permanent vegetation quadrats on Olkiluoto island. Establishment and results from the first inventory

International Nuclear Information System (INIS)

Huhta, A.P.; Korpela, L.

2006-05-01

This report describes in detail the vegetation quadrats established inside the permanent, follow-up sample plots (Forest Extensive High-level monitoring plots, FEH) on Olkiluoto Island. During summer 2005 a total of 94 sample plots (a 30 m 2 ), each containing eight quadrats (a 1m 2 ), were investigated. The total number of sampled quadrats was 752. Seventy of the 94 plots represent coniferous stands: 57 Norway spruce-dominated and 13 Scots pine-dominated stands. Ten of the plots represent deciduous, birch-dominated (Betula spp.) stands, 7 plots common alder-dominated (Alnus glutinosa) stands, and seven plots are mires. The majority of the coniferous tree stands were growing on sites representing various succession stages of the Myrtillus, Vaccinium-Myrtillus and Deschampsia-Myrtillus forest site types. The pine-dominated stands growing on exposed bedrock clearly differed from the other coniferous stands: the vegetation was characterised by the Cladina, Calluna-Cladina and Empetrum-Vaccinium vitis-idaea/Vaccinium Myrtillus forest site types. The deciduous stands were characterized by tall grasses, especially Calamagrostis epigejos, C. purpurea and Deschampsia flexuosa. The vegetation of the deciduous stands dominated by common alder represented grove-like sites and seashore groves. Typical species for mires included Calamagrostis purpurea, Calla palustris, Equisetum sylvaticum, and especially white mosses (Sphagnum spp.). A total of 184 vascular plant species were found growing within the quadrats. Due to the high number of quadrats in these forests, the spruce stands had the highest total number of species, but the birch and alder-dominated forests had the highest average number of species per quadrat. This basic inventory of the permanent vegetation quadrats on Olkiluoto Island provides a sound starting point for future vegetation surveys. Guidelines for future inventories and supplementary sampling are given in the discussion part of this report. (orig.)

Effects of botanical antifeedants on Melolontha melolontha grub feeding on Scots pine roots

Directory of Open Access Journals (Sweden)

Skrzecz Iwona

2014-09-01

Full Text Available The aim of the study was to evaluate the possibility of using botanic antifeedants to reduce the damage caused by Melolontha spp. grubs. To achieve the objective, the experiments were established in semi-field conditions to estimate the antifeedant activity of rutin, quercetin (flavonoids from buckwheat Fagopyrum esculentum and an extract from black alder Alnus glutinosa leaves against Melolontha melolontha grubs. The grubs were placed individually in the pots with a soil in which 2 year old Pinus sylvestris trees were planted. The pots were put in garden pavilions placed in the open area. Then the soil in the pots were watered with the emulsions of rutin, quercetin, an extract from A. glutinosa leaves, and with pure water-comparative variant. After 4 months, the weight and mortality of grubs were compared, as well as the weight of tree roots in all pots.

Imino Diels-Alder-Based Construction of a Piperidine A-Ring Unit for Total Synthesis of the Marine Hepatotoxin Cylindrospermopsin.

Science.gov (United States)

Heintzelman, Geoffrey R.; Weinreb, Steven M.; Parvez, Masood

1996-07-12

The synthesis of a piperidine A-ring precursor to the alkaloid cylindrospermopsin (1) is described. The initial approach to the A-ring precursor focused on the imino Diels-Alder reaction of diene 8 with ethyl (N-tosylimino)acetate (9) to form the cycloadduct 10 as a single stereoisomer. However, all attempts to convert ester 10 to a requisite diene such as 5 were unsuccessful. An alternative strategy involved the Diels-Alder cycloaddition of N-tosylimine 9 with oxygenated diene 19 under either thermal or Lewis acid-catalyzed conditions to produce a mixture of cis and trans enones 20 and 21. Although the undesired cis-enone 20 was the major product under all reaction conditions, it could be converted to the desired trans enone 21 by acid-catalyzed isomerization. Copper-mediated conjugate addition of vinylmagnesium bromide to cis-enone 20 followed by stereoselective ketone reduction with L-Selectride produced alcohol 23, whose structure was confirmed by X-ray crystallography. Similarly, trans-enone 21 was converted to alcohol 25 whose structure and stereochemistry were also established by X-ray analysis. Alcohol 25 was then protected as the silyl ether 26, which was hydroborated at the terminal olefin to produce primary alcohol ester 28having the stereochemistry and functionality needed for cylindrospermopsin.

Grafting methyl acrylic onto carbon fiber via Diels-Alder reaction for excellent mechanical and tribological properties of phenolic composites

Science.gov (United States)

Fei, Jie; Duan, Xiao; Luo, Lan; Zhang, Chao; Qi, Ying; Li, Hejun; Feng, Yongqiang; Huang, Jianfeng

2018-03-01

Carbon fibers (CFs) were grafted with methyl acrylic via Diels-Alder reaction at the different oil bath temperature effectively creating a carboxyl functionalized surface. The effect of grafting temperature on the surface morphology and functional groups of carbon fibers were investigated by FTIR, Raman spectroscopy, XPS and SEM respectively. The results showed that the optimal grafting temperature was 80 °C, and the relative surface coverage by carboxylic acid groups increased from an initial 5.16% up to 19.30% significantly improved the chemical activity without damaging the skin and core region of the carbon fibers. Mechanical property tests indicated that the shear and tensile strength of the sample with the grafting temperature of 80 °C (CFRP-3) increased obviously by 90.3% and 78.7%, respectively, compared with the pristine carbon fibers reinforced composite. Further, the sample CFRP-3 exhibited higher and more stable friction coefficient and improved wear resistance, while the wear rate decreased 52.7%, from 10.8 × 10-6 to 5.1 × 10-6 mm3/N m. The present work shows that grafting methyl acrylic via Diels-Alder reaction could be a highly efficient and facile method to functionalize carbon fibers for advanced composites.

Green Transformational Leadership and Green Performance: The Mediation Effects of Green Mindfulness and Green Self-Efficacy

OpenAIRE

Yu-Shan Chen; Ching-Hsun Chang; Yu-Hsien Lin

2014-01-01

No prior literature explores the influence of green transformational leadership on green performance, thus, this study develops a novel research framework to fill the research gap. This study investigates the influence of green transformational leadership on green performance and discusses the mediation effects of green mindfulness and green self-efficacy by means of structural equation modeling (SEM). The results indicate that green transformational leadership positively influences green min...

GREEN PACKAGING, GREEN PRODUCT, GREEN ADVERTISING, PERSEPSI, DAN MINAT BELI KONSUMEN

Directory of Open Access Journals (Sweden)

Imam Santoso

2016-12-01

Full Text Available Environmental problems become one of the strategic issues in achieving global competitiveness. One of the issues is products that are made from environmental friendly materials or known as green product. Furthermore, in green products marketing, the company also uses green packaging and green advertising concept. This study aimed to analyze the effect of green packaging, green products, and green advertising on consumer perception and purchasing intention. The study was conducted in Ketawanggede Village, Lowokwaru Sub-district, Malang City. The sampling method used nonprobability accidential sampling techniques. The numbers of respondents were 113 consumers in study site. Data were collected by interview using questionnaires. The method of analysis used Generalized Structured Component Analysis (GSCA. The analysis showed that the green packaging, green products, and green advertising had positive significant influence on consumer perceptions. Meanwhile, green product and consumer perception had positive significant influence on purchasing interest, but the green packaging and green advertising has not found sufficient evidence in influencing purchasing intention.

Syntheses of the hexahydroindene cores of indanomycin and stawamycin by combinations of iridium-catalyzed asymmetric allylic alkylations and intramolecular Diels-Alder reactions.

Science.gov (United States)

Gärtner, Martin; Satyanarayana, Gedu; Förster, Sebastian; Helmchen, Günter

2013-01-02

Short and concise syntheses of the hexahydroindene cores of the antibiotics indanomycin (X-14547 A) and stawamycin are presented. Key methods used are an asymmetric iridium-catalyzed allylic alkylation, a modified Julia olefination, a Suzuki-Miyaura coupling, and an intramolecular Diels-Alder reaction. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of cyclopentadienyl capped polyethylene and subsequent block copolymer formation via hetero Diels-Alder (HDA) chemistry.

Science.gov (United States)

Espinosa, Edgar; Glassner, Mathias; Boisson, Christophe; Barner-Kowollik, Christopher; D'Agosto, Franck

2011-09-15

In the current contribution it is demonstrated - for the first time - that poly(ethylene) (M(n) = 1,400 as well as 2,800 g  ·  mol(-1) , PDI = 1.2) can be readily equipped with highly reactive cyclopentadienyl (Cp) end groups. The Cp terminal poly(ethylene) can subsequently be reacted in an efficient hetero Diels-Alder (HDA) reaction with macromolecules (poly(isobornyl acrylate) (M(n) = 4,600 g  ·  mol(-1) , PDI = 1.10) and poly(styrene) (M(n) = 6,300 g  ·  mol(-1) , PDI = 1.13) featuring strongly electron withdrawing thiocarbonyl thio end groups, prepared via reversible addition fragmentation chain transfer (RAFT) polymerization employing benzylpyridin-2-yldithioformate (BPDF) as transfer agent. The resulting block copolymers have been analyzed via high-temperature size exclusion chromatography (SEC) as well as nuclear magnetic resonance (NMR) spectroscopy. The current system allows for the removal of the excess of the non-poly(ethylene) containing segment via filtration of the poly(ethylene)-containing block copolymer. However, the reaction temperatures need to be judiciously selected. Characterization of the generated block copolymers at elevated temperatures can lead - depending on the block copolymer type - to the occurrence of retro Diels-Alder processes. The present study thus demonstrates that RAFT-HDA ligation can be effectively employed for the generation of block copolymers containing poly(ethylene) segments. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of Pyrrolo[1,2-a]pyrimidine Enantiomers via Domino Ring-Closure followed by Retro Diels-Alder Protocol

Directory of Open Access Journals (Sweden)

Beáta Fekete

2017-04-01

Full Text Available From 2-aminonorbornene hydroxamic acids, a simple and efficient method for the preparation of pyrrolo[1,2-a]pyrimidine enantiomers is reported. The synthesis is based on domino ring-closure followed by microwave-induced retro Diels-Alder (RDA protocols, where the chirality of the desired products is transferred from norbornene derivatives. The stereochemistry of the synthesized compounds was proven by X-ray crystallography. The absolute configuration of the product is determined by the configuration of the starting amino hydroxamic acid.

Cross-conjugated Trienamine Catalysis with α'-Alkylidene 2-Cyclohexenones: Application in β,γ-Regioselective Aza-Diels-Alder Reaction.

Science.gov (United States)

Zhou, Zhi; Wang, Zhou-Xiang; Ouyang, Qin; Xiao, Wei; Du, Wei; Chen, Ying-Chun

2017-02-24

Endo-type cross-conjugated trienamines between highly congested α'-alkylidene 2-cyclohexenones and a chiral primary amine catalyst serve as HOMO-raised dienophiles in inverse-electron-demand aza-Diels-Alder cycloadditions with a number of 1-azadiene substrates. The reactions exhibit exclusive β,γ-regioselectivity, and multifunctional products with high molecular complexity are efficiently constructed in excellent diastereo- and enantioselectivity (>19:1 d.r., up to 99 % ee). © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of Pyrrolo[1,2-a]pyrimidine Enantiomers via Domino Ring-Closure followed by Retro Diels-Alder Protocol.

Science.gov (United States)

Fekete, Beáta; Palkó, Márta; Haukka, Matti; Fülöp, Ferenc

2017-04-13

From 2-aminonorbornene hydroxamic acids, a simple and efficient method for the preparation of pyrrolo[1,2- a ]pyrimidine enantiomers is reported. The synthesis is based on domino ring-closure followed by microwave-induced retro Diels-Alder (RDA) protocols, where the chirality of the desired products is transferred from norbornene derivatives. The stereochemistry of the synthesized compounds was proven by X-ray crystallography. The absolute configuration of the product is determined by the configuration of the starting amino hydroxamic acid.

Nitroso Diels-Alder (NDA) Reaction as an Efficient Tool for the Functionalization of Diene-Containing Natural Products

Science.gov (United States)

Carosso, Serena; Miller, Marvin J.

2014-01-01

This review describes the use of nitroso Diels-Alder reactions for the functionalization of complex diene-containing natural products in order to generate libraries of compounds with potential biological activity. The application of this methodology to the structural modification of a series of natural products (thebaine, steroidal dienes, rapamycin, leucomycin, colchicine, isocolchicine and piperine) is discussed using relevant examples from the literature from 1973 onwards. The biological activity of the resulting compounds is also discussed. Additional comments are provided that evaluate the methodology as a useful tool in organic, bioorganic and medicinal chemistry. PMID:25119424

Ground states of molecules. XLIX. MINDO/3 study of the retro-diels-alder reaction of cyclohexene

International Nuclear Information System (INIS)

Dewar, M.J.S.; Olivella, S.; Rzepa, H.S.

1978-01-01

The retro-Diels-Alder reaction of cyclohexene to form ethylene and butadiene has been studied, using MINDO/3. The transition state is predicted to be very unsymmetric, corresponding to weakening of one of the two breaking CC bonds. The calculated entropy of activation agrees well with experiment and the calculated secondary isotope effects for 4,4-dideuteriocyclohexene and 4,4,5,5-tetradeuteriocyclohexene are similar to those measured for an analogous reaction by Taagepera and Thornton. Discrepancies between the conclusions reached here and those from recent ab-initio calculations are discussed. 4 tables, 3 figures, 53 references

GREEN PACKAGING, GREEN PRODUCT, GREEN ADVERTISING, PERSEPSI, DAN MINAT BELI KONSUMEN

OpenAIRE

Imam Santoso; Rengganis Fitriani

2016-01-01

Environmental problems become one of the strategic issues in achieving global competitiveness. One of the issues is products that are made from environmental friendly materials or known as green product. Furthermore, in green products marketing, the company also uses green packaging and green advertising concept. This study aimed to analyze the effect of green packaging, green products, and green advertising on consumer perception and purchasing intention. The study was conducted in Ketawangg...

High Pressure Diels Alder Reactions of 1-Vinyl-2,2,6-trimethylcyclohexene Catalyzed by Chiral Lewis Acids; An Enantioselective Route to a Drimane Sesquiterpene Precursor.

NARCIS (Netherlands)

Knol, Joop; Meetsma, Auke; Feringa, Bernard

1995-01-01

The Diels Alder reaction of 1-vinyl-2,2,6-trimethylcyclohexene and 3-((E)-3-(methoxycarbonyl)propenoyl)-1,3-oxazolidin-2-one under high pressure, catalyzed by a chiral bis-imine copper(II) complex, yields a drimane sesquiterpene precursor in a highly regio- and diastereoselective manner with

Transpiration of shrub species, Alnus firma under changing atmospheric environments in montane area, Japan

Science.gov (United States)

Miyazawa, Y.; Maruyama, A.; Inoue, A.

2014-12-01

In the large caldera of Mt. Aso in Japan, grasslands have been traditionally managed by the farmers. Due to changes in the social structure of the region, a large area of the grassland has been abandoned and was invaded by the shrubs with different hydrological and ecophysiological traits. Ecophysiological traits and their responses to seasonally changing environments are fundamental to project the transpiration rates under changing air and soil water environments, but less is understood. We measured the tree- and leaf-level ecophysiological traits of a shrub, Alnus firma in montane region where both rainfall and soil water content drastically changes seasonally. Sap flux reached the annual peak in evaporative summer (July-August) both in 2013 and 2014, although the duration was limited within a short period due to the prolonged rainy season before summer (2014) and rapid decrease in the air vapor pressure deficit (D) in late summer. Leaf ecophysiological traits in close relationship with gas exchange showed modest seasonal changes and the values were kept at relatively high levels typical in plants with nitrogen fixation under nutrient-poor environments. Stomatal conductance, which was measured at leaf-level measurements and sap flux measurements, showed responses to D, which coincided with the theoretical response for isohydric leaves. A multilayer model, which estimates stand-level transpiration by scaling up the leaf-level data, successfully captured the temporal trends in sap flux, suggesting that major processes were incorporated. Thus, ecophysiological traits of A. firma were characterized by the absence of responses to seasonally changing environments and the transpiration rate was the function of the interannually variable environmental conditions.

Greens of the European Green Capitals

Science.gov (United States)

Cömertler, Seval

2017-10-01

Well established and maintained green areas have a key role on reaching the high quality of life and sustainability in urban environments. Therefore, green areas must be carefully accounted and evaluated in the urban planning affairs. In this context, the European Green Capitals, which attach a great importance to the green areas, have a great potential to act as a role model for both small and big cities in all around the world. These leading cities (chronologically, Stockholm, Hamburg, Vitoria-Gasteiz, Nantes, Copenhagen, Bristol, Ljubljana, Essen and Nijmegen) are inspiring for the other cities which seek to achieve more sustainable and environmentally friendly places through green areas. From this point of view, the aim of this paper was to investigate the green areas of the European Green Capitals. The paper covered whole European Green Capitals, and the application form of each Green Capital was used as a primary data source. Consequently, the paper put forwarded that the European Green Capitals have considerably large amount and high proportion of green areas. Further, these cities provide an excellent access to the public green areas. As a result of abundant provision and proper distribution, the almost all citizens in most of the Green Capitals live within a distance of 300 meters to a green area. For further researches, the paper suggested that these green capitals should be investigated in terms of their efforts, measures, goals and plans, policies and implications to administer, to protect, to enhance and to expand the green areas.

Blue-Emitting Arylalkynyl Naphthalene Derivatives via a Hexadehydro-Diels-Alder Cascade Reaction.

Science.gov (United States)

Xu, Feng; Hershey, Kyle W; Holmes, Russell J; Hoye, Thomas R

2016-10-05

We describe here three alkynyl substituted naphthalenes that display promising luminescence characteristics. Each compound is easily and efficiently synthesized in three steps by capitalizing on the hexadehydro-Diels-Alder (HDDA) cycloisomerization reaction in which an intermediate benzyne is captured by tetraphenylcyclopentadienone, a classical trap for benzyne itself. These compounds luminesce in the deep blue when stimulated either optically (i.e., photoluminescence in both solution and solid films) or electrically [in a light-emitting diode (LED)]. The photophysical properties are relatively insensitive to the electronic nature of the substituents (H, OMe, CO 2 Me) that define these otherwise identical compounds. Overall, our observations suggest that the twisted nature of the five adjacent aryl groups serves to minimize the intermolecular interaction between core naphthalene units in different sample morphologies. These compounds represent promising leads for the identification of others of value as the emissive component of organic LEDs (OLEDs).

From green architecture to architectural green

DEFF Research Database (Denmark)

Earon, Ofri

2011-01-01

that describes the architectural exclusivity of this particular architecture genre. The adjective green expresses architectural qualities differentiating green architecture from none-green architecture. Currently, adding trees and vegetation to the building’s facade is the main architectural characteristics...... they have overshadowed the architectural potential of green architecture. The paper questions how a green space should perform, look like and function. Two examples are chosen to demonstrate thorough integrations between green and space. The examples are public buildings categorized as pavilions. One......The paper investigates the topic of green architecture from an architectural point of view and not an energy point of view. The purpose of the paper is to establish a debate about the architectural language and spatial characteristics of green architecture. In this light, green becomes an adjective...

High Genetic Diversity and Distinctiveness of Rear-Edge Climate Relicts Maintained by Ancient Tetraploidisation for Alnus glutinosa

Science.gov (United States)

Lepais, Olivier; Muller, Serge D.; Ben Saad-Limam, Samia; Benslama, Mohamed; Rhazi, Laila; Belouahem-Abed, Djamila; Daoud-Bouattour, Amina; Gammar, Amor Mokhtar; Ghrabi-Gammar, Zeineb; Bacles, Cécile Fanny Emilie

2013-01-01

Populations located at the rear-edge of a species’ distribution may have disproportionate ecological and evolutionary importance for biodiversity conservation in a changing global environment. Yet genetic studies of such populations remain rare. This study investigates the evolutionary history of North-African low latitude marginal populations of Alnus glutinosa Gaertn., a European tree species that plays a significant ecological role as a keystone of riparian ecosystems. We genotyped 551 adults from 19 populations located across North Africa at 12 microsatellite loci and applied a coalescent-based simulation approach to reconstruct the demographic and evolutionary history of these populations. Surprisingly, Moroccan trees were tetraploids demonstrating a strong distinctiveness of these populations within a species otherwise known as diploid. Best-fitting models of demographic reconstruction revealed the relict nature of Moroccan populations that were found to have withstood past climate change events and to be much older than Algerian and Tunisian populations. This study highlights the complex demographic history that can be encountered in rear-edge distribution margins that here consist of both old stable climate relict and more recent populations, distinctively diverse genetically both quantitatively and qualitatively. We emphasize the high evolutionary and conservation value of marginal rear-edge populations of a keystone riparian species in the context of on-going climate change in the Mediterranean region. PMID:24098677

Magnetically Separable Iron Oxide Nanoparticles: An Efficient and Reusable Catalyst for Imino Diels-Alder Reaction

Energy Technology Data Exchange (ETDEWEB)

Basavegowda, Nagaraj; Mishra, Kanchan; Lee, Yong Rok; Joh, Young-Gull [Yeungnam University, Gyeongsan (Korea, Republic of)

2016-02-15

Iron oxide nanoparticles were synthesized using Saururus chinensis (S. chinensis) leaf extract as a reducing and stabilizing agent via ultrasonication. The size, morphology, crystallinity, elemental composition, weight loss, surface chemical state, and magnetic properties of the synthesized nanoparticles were investigated. The synthe-sized nanoparticles were used as an efficient and recyclable catalyst for the synthesis of a variety of 2-methyl-4-substituted-1,2,3,4-tetrahydroquinoline derivatives by the imino Diels-Alder reaction. After the reaction, the catalyst was recovered by an external magnetic field. The recovered catalyst was then reused in a subsequent reaction under identical conditions. The recycled iron oxide nanoparticles (IONPs) were reused five times with-out any significant loss of catalytic activity.

Magnetically Separable Iron Oxide Nanoparticles: An Efficient and Reusable Catalyst for Imino Diels-Alder Reaction

International Nuclear Information System (INIS)

Basavegowda, Nagaraj; Mishra, Kanchan; Lee, Yong Rok; Joh, Young-Gull

2016-01-01

Iron oxide nanoparticles were synthesized using Saururus chinensis (S. chinensis) leaf extract as a reducing and stabilizing agent via ultrasonication. The size, morphology, crystallinity, elemental composition, weight loss, surface chemical state, and magnetic properties of the synthesized nanoparticles were investigated. The synthe-sized nanoparticles were used as an efficient and recyclable catalyst for the synthesis of a variety of 2-methyl-4-substituted-1,2,3,4-tetrahydroquinoline derivatives by the imino Diels-Alder reaction. After the reaction, the catalyst was recovered by an external magnetic field. The recovered catalyst was then reused in a subsequent reaction under identical conditions. The recycled iron oxide nanoparticles (IONPs) were reused five times with-out any significant loss of catalytic activity.

Irreversible endo-Selective Diels–Alder Reactions of Substituted Alkoxyfurans: A General Synthesis of endo-Cantharimides

Science.gov (United States)

Foster, Robert W; Benhamou, Laure; Porter, Michael J; Bučar, Dejan-Krešimir; Hailes, Helen C; Tame, Christopher J; Sheppard, Tom D

2015-01-01

The [4+2] cycloaddition of 3-alkoxyfurans with N-substituted maleimides provides the first general route for preparing endo-cantharimides. Unlike the corresponding reaction with 3H furans, the reaction can tolerate a broad range of 2-substitued furans including alkyl, aromatic, and heteroaromatic groups. The cycloaddition products were converted into a range of cantharimide products with promising lead-like properties for medicinal chemistry programs. Furthermore, the electron-rich furans are shown to react with a variety of alternative dienophiles to generate 7-oxabicyclo[2.2.1]heptane derivatives under mild conditions. DFT calculations have been performed to rationalize the activation effect of the 3-alkoxy group on a furan Diels–Alder reaction. PMID:25756502

Comparison of planted soil infiltration systems for treatment of log yard runoff.

Science.gov (United States)

Hedmark, Asa; Scholz, Miklas; Aronsson, Par; Elowson, Torbjorn

2010-07-01

Treatment of log yard runoff is required to avoid contamination of receiving watercourses. The research aim was to assess if infiltration of log yard runoff through planted soil systems is successful and if different plant species affect the treatment performance at a field-scale experimental site in Sweden (2005 to 2007). Contaminated runoff from the log yard of a sawmill was infiltrated through soil planted with Alnus glutinosa (L.) Gärtner (common alder), Salix schwerinii X viminalis (willow variety "Gudrun"), Lolium perenne (L.) (rye grass), and Phalaris arundinacea (L.) (reed canary grass). The study concluded that there were no treatment differences when comparing the four different plants with each other, and there also were no differences between the tree and the grass species. Furthermore, the infiltration treatment was effective in reducing total organic carbon (55%) and total phosphorus (45%) concentrations in the runoff, even when the loads on the infiltration system increased from year to year.

Metabolic activity of tree saps of different origin towards cultured human cells in the light of grade correspondence analysis and multiple regression modeling

Directory of Open Access Journals (Sweden)

Artur Wnorowski

2017-06-01

Full Text Available Tree saps are nourishing biological media commonly used for beverage and syrup production. Although the nutritional aspect of tree saps is widely acknowledged, the exact relationship between the sap composition, origin, and effect on the metabolic rate of human cells is still elusive. Thus, we collected saps from seven different tree species and conducted composition-activity analysis. Saps from trees of Betulaceae, but not from Salicaceae, Sapindaceae, nor Juglandaceae families, were increasing the metabolic rate of HepG2 cells, as measured using tetrazolium-based assay. Content of glucose, fructose, sucrose, chlorides, nitrates, sulphates, fumarates, malates, and succinates in sap samples varied across different tree species. Grade correspondence analysis clustered trees based on the saps’ chemical footprint indicating its usability in chemotaxonomy. Multiple regression modeling showed that glucose and fumarate present in saps from silver birch (Betula pendula Roth., black alder (Alnus glutinosa Gaertn., and European hornbeam (Carpinus betulus L. are positively affecting the metabolic activity of HepG2 cells.

The Influence of Proactive Green Innovation and Reactive Green Innovation on Green Product Development Performance: The Mediation Role of Green Creativity

Directory of Open Access Journals (Sweden)

Yu-Shan Chen

2016-09-01

Full Text Available This study fills the research gap in the exploration of the relationships between both proactive and reactive green innovations and green product development performance, and examines the mediating effect of green creativity. Structural equation modeling (SEM is utilized to test the hypotheses. From the sample of 146 valid respondents, the results show that proactive green innovation positively affects green creativity and green product development performance, and green creativity positively affects green product development performance. In addition, our findings also indicate that the relationship between proactive green innovation and green product development performance is partially mediated by green creativity. Accordingly, green creativity plays a critical role for companies to achieve a great green product development performance. However, reactive green innovation does not significantly influence green creativity and green product development performance. Companies should develop proactive green innovation rather than reactive green innovation in order to enhance their green creativity and increase their product development performance.

Elucidation of Diels-Alder Reaction Network of 2,5-Dimethylfuran and Ethylene on HY Zeolite Catalyst

Energy Technology Data Exchange (ETDEWEB)

Do, Phuong T. M. [Univ. of Delaware, Newark, DE (United States); McAtee, Jesse R. [Univ. of Delaware, Newark, DE (United States); Watson, Donald A. [Univ. of Delaware, Newark, DE (United States); Lobo, Raul F. [Univ. of Delaware, Newark, DE (United States)

2012-12-12

The reaction of 2,5-dimethylfuran and ethylene to produce p-xylene represents a potentially important route for the conversion of biomass to high-value organic chemicals. Current preparation methods suffer from low selectivity and produce a number of byproducts. Using modern separation and analytical techniques, the structures of many of the byproducts produced in this reaction when HY zeolite is employed as a catalyst have been identified. From these data, a detailed reaction network is proposed, demonstrating that hydrolysis and electrophilic alkylation reactions compete with the desired Diels–Alder/dehydration sequence. This information will allow the rational identification of more selective catalysts and more selective reaction conditions.

Inverse-Electron-Demand Diels-Alder Reactions: Principles and Applications.

Science.gov (United States)

Png, Zhuang Mao; Zeng, Huining; Ye, Qun; Xu, Jianwei

2017-09-05

Inverse-electron-demand Diels-Alder (iEDDA) reactions are an intriguing class of cycloaddition reactions that have attracted increasing attention for their application in bioorthogonal chemistry, the total synthesis of natural products, and materials science. In many cases, the application of the iEDDA reaction has been demonstrated as an innovative approach to achieve target structures. The theoretical aspects of this class of reactions are of particular interest for scientists as a means to understand the various factors, such as steric strain and electron density of the attached groups, that govern the reaction and thus to elucidate the reaction mechanism. This review aims to summarize both theoretical investigations and application-driven research work on the iEDDA reaction. First, the historical aspects and the theoretical basis of the reaction, especially recent advances in time-dependent density functional theory (TD-DFT) calculations, as well as catalysis strategies will be highlighted and discussed. Second, the applications of this novel reaction in the context of materials science, bioorthogonal chemistry, and total synthesis of natural products will be elaborated with selected recent examples. The challenges and opportunities of the iEDDA reaction will be highlighted to give more insight into its potential applications in many other research areas. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pengaruh Green Marketing Hotel Terhadap Green Consumer Behavior

OpenAIRE

Yo Fernandez, Eunike Christe; Tjoanda, Evelyn

2017-01-01

Penelitian ini dilakukan untuk mengetahui pengaruh dari green marketing hotel terhadap green consumer behavior. Green marketing memiliki 3 dimensi, yaitu green product, green price, dan green promotion. Penelitian ini melibatkan 272 responden masyarakat Surabaya dan menggunakan metode regresi linear berganda. Hasil penelitian menunjukkan bahwa green product dan green price berpengaruh secara positif dan signifikan sedangkan green promotion berpengaruh namun tidak signifikan terhadap green con...

Bio-orthogonal Fluorescent Labelling of Biopolymers through Inverse-Electron-Demand Diels-Alder Reactions.

Science.gov (United States)

Kozma, Eszter; Demeter, Orsolya; Kele, Péter

2017-03-16

Bio-orthogonal labelling schemes based on inverse-electron-demand Diels-Alder (IEDDA) cycloaddition have attracted much attention in chemical biology recently. The appealing features of this reaction, such as the fast reaction kinetics, fully bio-orthogonal nature and high selectivity, have helped chemical biologists gain deeper understanding of biochemical processes at the molecular level. Listing the components and discussing the possibilities and limitations of these reagents, we provide a recent snapshot of the field of IEDDA-based biomolecular manipulation with special focus on fluorescent modulation approaches through the use of bio-orthogonalized building blocks. At the end, we discuss challenges that need to be addressed for further developments in order to overcome recent limitations and to enable researchers to answer biomolecular questions in more detail. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

A mechanochemical study of the effects of compression on a Diels-Alder reaction

Science.gov (United States)

Jha, Sanjiv K.; Brown, Katie; Todde, Guido; Subramanian, Gopinath

2016-08-01

We examine the effects of compressive external forces on the mechanisms of the parent Diels-Alder (DA) reaction between butadiene and ethylene. Reaction pathways and transition states were calculated using the nudged elastic band method within a mechanochemical framework at the CASSCF(6,6)/6-31G**, as well as the B3LYP/6-311++G** levels of theory. Our results suggest that compressive hydrostatic pressure lowers the energy barrier for the parent DA reaction while suppressing the undesirable side reaction, thereby leading to a direct increase in the yield of cyclohexene. Compressive pressure also increases the exothermicity of the parent DA reaction, which would lead to increased temperatures in a reaction vessel and thereby indirectly increase the yield of cyclohexene. Our estimates indicate that the compression used in our study corresponds to a range of 68 MPa-1410 MPa.

T3P- A Novel Catalyst for Aza-Diels-Alder Reaction: One-Pot Synthesis of Pyrano[3,2-c]quinolines and furano[3,2-c]quinolines

Directory of Open Access Journals (Sweden)

T. S. R. Prasanna

2011-01-01

Full Text Available T3P was found to be an efficient catalyst for the Aza-Diels–Alder reactions of aldimines with dihydropyran or dihydrofuran to afford the corresponding pyrano-and furo [3,2-c]quinolines in high yields with high diastereoselectivity in a short period of time.

Synthesis of a Self-Healing Polymer Based on Reversible Diels-Alder Reaction: An Advanced Undergraduate Laboratory at the Interface of Organic Chemistry and Materials Science

Science.gov (United States)

Weizman, Haim; Nielsen, Christian; Weizman, Or S.; Nemat-Nasser, Sia

2011-01-01

This laboratory experiment exposes students to the chemistry of self-healing polymers based on a Diels-Alder reaction. Students accomplish a multistep synthesis of a monomer building block and then polymerize it to form a cross-linked polymer. The healing capability of the polymer is verified by differential scanning calorimetry (DSC) experiments.…

Contribución al conocimiento de la biología y taxonomía de un hongo del género Phytium aislado del "aliso", Alnus acuminata HBK

Directory of Open Access Journals (Sweden)

Marina Correa de Restrepo

1990-01-01

Full Text Available Some biological aspects of an isolated fungus of Alnus acuminata roots were studied. It bas been found Tbat between OOC and 4°C tbe fungi grows fast. This condition can result in a important factor in the ecophysiology of 'Aliso' populations, that grows in secondary forests at sub-paramo, After a review of the taxonomic literature, we placed it in the Phytium genus, but not in a particular described species. We assume that it is a new species. We modificated the microculture technique that was simpler and safer and them we made direct observations about tbe fungus growtb and development. As for now it is nominated as Phytiun near Mammillatum Meurs. Palabras Claves: Phytium, bongos, A/nus acuminata HBK., "Aliso".

Green(ing) infrastructure

CSIR Research Space (South Africa)

Van Wyk, Llewellyn V

2014-03-01

Full Text Available the generation of electricity from renewable sources such as wind, water and solar. Grey infrastructure – In the context of storm water management, grey infrastructure can be thought of as the hard, engineered systems to capture and convey runoff..., pumps, and treatment plants.  Green infrastructure reduces energy demand by reducing the need to collect and transport storm water to a suitable discharge location. In addition, green infrastructure such as green roofs, street trees and increased...

Novel UTP derivative with diene-containing spacer arm for Diels-Alder reaction: potential tool for radioactive or fluorescent detection upon its incorporation into ribonucleic acid

Czech Academy of Sciences Publication Activity Database

Točík, Zdeněk; Krásný, Libor; Kovačková, Soňa; Rejman, Dominik; Rosenberg, Ivan

2007-01-01

Roč. 6, č. 5 (2007), s. 357 ISSN 1535-3508. [International Conference of the European Society for Molecular Imaging /2./. 14.06.2007-15.06.2007, Naples] Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z50520701 Keywords : UTP derivative * Diels - Alder reaction * diene * spacer arm Subject RIV: CC - Organic Chemistry

ANTIMICROBIAL ACTIVITY OF THE SUBSTANCES RECEIVED FROM RAW MATERIALS OF BIRCH FAMILY PLANTS

Directory of Open Access Journals (Sweden)

Fedchenkova Yu.A

2016-12-01

Full Text Available Introduction. In accordance with the last events in Ukraine (considering military operations in anti-terrorist operation in the Luhansk and Donetsk regions the domestic medicine is in great need in preparations with antimicrobial activity. Our attention as the sources of receiving biologically active substances with antimicrobial activity was drawn with birch Betulaceae family plants – hazel ordinary Corylus avellana L. and black alder Alnus glutinosa (L. Gaertn. It is known that in medicine the leaves of hazel ordinary are used as antiseptic, anti-inflammatory, vesselrestorative drug, and the leaves of black alder reveal the antiinflammatory, astringent, wound healing, spasmolytic and choleretic action. However, the drugs with antimicrobial action received from the leaves of these plants are absent on the market of Ukraine. Therefore the studying of antimicrobial activity of this type of raw materials received from hazel ordinary and black alder, for creation of new medicines, is now one of the main directions in pharmacy. For this purpose we have revealed tinctures, spirit, lipophilic and polysacharid fractions received from the leaves of hazel ordinary and black alder. The purpose of our research is studying of antimicrobial activity of revealed substance received from the leaves of black alder and hazel ordinary. Materials and methods. There were being examined tinctures, lipophilic, spirit and polysacharid fractions received from the leaves of hazel ordinary and black alder. The test of antimicrobial effect of substances was carried out by means of serial dilution concerning the following six reference cultures: Staphylococcus aureus ATCC 6538-P, Candida albicans ATCC 885-653, Escherichia coli ATCC 25922, Bacillus subtilis ATCC 6833, Bacillus cereus ATCC 10702, Pseudomonas aeruginosa ATCC 9027, according to the State Pharmacopoeia of Ukraine, in the Department of Microbiology and Immunology of KMAPE. For the experiment there was prepared

Pre-logging Treatment of Invasive Glossy Buckthorn (Frangula alnus Mill. Promotes Regeneration of Eastern White Pine (Pinus strobus L.

Directory of Open Access Journals (Sweden)

Thomas D. Lee

2016-12-01

Full Text Available Non-native glossy buckthorn (Frangula alnus Mill. is invasive in forests of the northeastern USA but little is known of its effects on tree regeneration. We tested whether killing buckthorn stems before logging reduces its post-logging abundance and increases the density and height of eastern white pine (Pinus strobus L. seedlings. Three 0.4 ha plots were clearcut, three were thinned, and three were left as controls. Each plot had previously been divided into three subplots that received different buckthorn treatments during the two years before logging. Buckthorn treatments were (1 stems cut at base five times; (2 stems cut once then heat killed four times; (3 untreated control. Three years post-logging, buckthorn density and stem height were unaffected by logging but equally reduced by the two buckthorn treatments. Buckthorn reduction increased density and height of pine seedlings, and seedling height also increased with logging. In the fifth year post-logging, pine height growth and biomass were greater in clearcut than in thinned treatments, greater in areas of buckthorn removal and, within treated subplots, greater in areas with low buckthorn density than in thickets of recovering buckthorn. Thus, although buckthorn inhibited regenerating pine, pre-logging destruction of buckthorn stems reduced such competition for at least four years.

Epoxy-Functionalized Porous Organic Polymers via the Diels-Alder Cycloaddition Reaction for Atmospheric Water Capture.

Science.gov (United States)

Byun, Yearin; Coskun, Ali

2018-03-12

The synthesis of highly microporous, epoxy-functionalized porous organic polymers (ep-POPs) by a one-pot, catalyst-free Diels-Alder cycloaddition polymerization is reported. The high oxygen content of ep-POPs offer efficient hydrogen-bonding sites for water molecules, thus leading to high water-uptake capacities up to 39.2-42.4 wt % under a wide temperature range of 5-45 °C, which covers the span of climatic conditions and manufacturing applications in which such materials might be used. Importantly, ep-POPs demonstrated regeneration temperatures as low as 55 °C, as well as excellent water stability, recyclability, and high specific surface areas up to 852 m 2  g -1 . © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrostatic catalysis of a Diels-Alder reaction

Science.gov (United States)

Aragonès, Albert C.; Haworth, Naomi L.; Darwish, Nadim; Ciampi, Simone; Bloomfield, Nathaniel J.; Wallace, Gordon G.; Diez-Perez, Ismael; Coote, Michelle L.

2016-03-01

It is often thought that the ability to control reaction rates with an applied electrical potential gradient is unique to redox systems. However, recent theoretical studies suggest that oriented electric fields could affect the outcomes of a range of chemical reactions, regardless of whether a redox system is involved. This possibility arises because many formally covalent species can be stabilized via minor charge-separated resonance contributors. When an applied electric field is aligned in such a way as to electrostatically stabilize one of these minor forms, the degree of resonance increases, resulting in the overall stabilization of the molecule or transition state. This means that it should be possible to manipulate the kinetics and thermodynamics of non-redox processes using an external electric field, as long as the orientation of the approaching reactants with respect to the field stimulus can be controlled. Here, we provide experimental evidence that the formation of carbon-carbon bonds is accelerated by an electric field. We have designed a surface model system to probe the Diels-Alder reaction, and coupled it with a scanning tunnelling microscopy break-junction approach. This technique, performed at the single-molecule level, is perfectly suited to deliver an electric-field stimulus across approaching reactants. We find a fivefold increase in the frequency of formation of single-molecule junctions, resulting from the reaction that occurs when the electric field is present and aligned so as to favour electron flow from the dienophile to the diene. Our results are qualitatively consistent with those predicted by quantum-chemical calculations in a theoretical model of this system, and herald a new approach to chemical catalysis.

Tandem Reaction of Cationic Copolymerization and Concertedly Induced Hetero-Diels-Alder Reaction Preparing Sequence-Regulated Polymers.

Science.gov (United States)

Matsumoto, Suzuka; Kanazawa, Arihiro; Kanaoka, Shokyoku; Aoshima, Sadahito

2017-06-14

A unique tandem reaction of sequence-controlled cationic copolymerization and site-specific hetero-Diels-Alder (DA) reaction is demonstrated. In the controlled cationic copolymerization of furfural and 2-acetoxyethyl vinyl ether (AcOVE), only the furan ring adjacent to the propagating carbocation underwent the hetero-DA reaction with the aldehyde moiety of another furfural molecule. A further and equally important feature of the copolymerization is that the obtained copolymers had unprecedented 2:(1 + 1)-type alternating structures of repeating sequences of two VE and one furfural units in the main chain and one furfural unit in the side chain. The specific DA reaction is attributed to the delocalization of the positive charge to the side furan ring.

Diels-Alder reactions for the rational design of benzo[b]thiophenes: DFT-based guidelines for synthetic chemists

Science.gov (United States)

Brasca, Romina; Kneeteman, María N.; Mancini, Pedro M. E.; Fabian, Walter M. F.

2012-02-01

In this work we studied the capability of several diene/dienophile pairs to undergo Diels-Alder (DA) reactions leading to benzo[b]thiophenes. A variety of synthetically and commercially available nitrothiophenes were chosen as dienophiles. Methyl 5-nitro-3-thiophenecarboxylate was selected as a potential strong electrophilic candidate based on some DFT-based properties and the substitution pattern of the expected product. The mechanistic details concerning the participation of this dienophile in polar DA reactions were investigated through a theoretical point of view. The results were compared with the experimental outcomes. This methodology should allow synthetic chemists to analyze DA reactions in detail in a stage prior to the synthetic job.

Customers’ Intention to Use Green Products: the Impact of Green Brand Dimensions and Green Perceived Value

Directory of Open Access Journals (Sweden)

Doszhanov Aibek

2015-01-01

Full Text Available This study aimed to identify the relationships between green brand dimension (green brand awareness, green brand image, and green brand trust, green perceived value and customer’s intention to use green products. Data was collected through structured survey questionnaire from 384 customers of three hypermarkets in Kuala-Lumpur. Data was analyzed based on multiple regression analysis. The results indicate that there are significant relationships between green brand awareness, green brand trust, green perceived value, and customer’s intention to use green products. However, green brand image was not found to have significant relationship with customer’s intention to use green products. The discussion presented suggestions for marketers and researchers interested in green branding.

The Influence of Proactive Green Innovation and Reactive Green Innovation on Green Product Development Performance: The Mediation Role of Green Creativity

OpenAIRE

Yu-Shan Chen; Tai-Wei Chang; Chun-Yu Lin; Pi-Yu Lai; Kuan-Hung Wang

2016-01-01

This study fills the research gap in the exploration of the relationships between both proactive and reactive green innovations and green product development performance, and examines the mediating effect of green creativity. Structural equation modeling (SEM) is utilized to test the hypotheses. From the sample of 146 valid respondents, the results show that proactive green innovation positively affects green creativity and green product development performance, and green creativity positivel...

Metaphysical green

DEFF Research Database (Denmark)

Earon, Ofri

2011-01-01

to adapt to urban environment. It explores the potential of Sensation of Green in the city. The paper questions whether the Sensation of Green could introduce a new spectrum of greens, beside the real green. It develops the term of metaphysical green – does green have to be green or can it be only...

The Role of Phytodiversity in Riparian Alder Forests in Supporting the Provision of Ecosystem Services

Directory of Open Access Journals (Sweden)

Mariničová Patrícia

2016-11-01

Full Text Available Nature, ecosystems and biodiversity provide human society with many benefits known as ecosystem services. Functional diversity is an important aspect of biodiversity. In this paper, we applied inductive approach to the identification, mapping and evaluation of ecosystem services of the Aegopodio-Alnetum glutinosae community in Tribeč Mts. The results from 2015 show that the alder floodplain forest represents one of the most productive forest ecosystems with seasonal maximum production of 59.03 g m−2, species diversity of N0 = 40 and functional diversity of FD = 10. The forage potential of this community is medium, the melliferous potential is high and the therapeutic potential was estimated as extremely rich in medicinal plants. From the functional groups for providing ecosystem services, woody plants and hemicryptophytes play the most significant role.

P-chiral 1-phosphanorbornenes: from asymmetric phospha-Diels-Alder reactions towards ligand design and functionalisation.

Science.gov (United States)

Möller, Tobias; Wonneberger, Peter; Sárosi, Menyhárt B; Coburger, Peter; Hey-Hawkins, Evamarie

2016-02-07

The principle of stereotopic face differentiation was successfully applied to 2H-phospholes which undergo a very efficient and highly stereoselective Diels-Alder reaction giving phosphorus-chiral 1-phosphanorbornenes with up to 87% yield. The observed reaction pathway has been supported by theoretical calculations showing that the cycloaddition reaction between 2H-phosphole 3a and the dienophile (5R)-(-)-menthyloxy-2(5H)-furanone (8) is of normal electron demand. Optically pure phosphanes were obtained by separation of the single diastereomers and subsequent desulfurisation of the sulfur-protected phosphorus atom. Finally, divergent ligand synthesis is feasible by reduction of the chiral auxiliary, subsequent stereospecific intramolecular Michael addition, and various functionalisations of the obtained key compound 13a. Furthermore, the unique structural properties of phospanorbornenes are presented and compared to those of phosphanorbornanes.

Computational Investigation of the Competition between the Concerted Diels-Alder Reaction and Formation of Diradicals in Reactions of Acrylonitrile with Non-Polar Dienes

Science.gov (United States)

James, Natalie C.; Um, Joann M.; Padias, Anne B.; Hall, H. K.; Houk, K. N.

2013-01-01

The energetics of the Diels-Alder cycloaddition reactions of several 1,3-dienes with acrylonitrile, and the energetics of formation of diradicals, were investigated with density functional theory (B3LYP and M06-2X) and compared to experimental data. For the reaction of 2,3-dimethyl-1,3-butadiene with acrylonitrile, the concerted reaction is favored over the diradical pathway by 2.5 kcal/mol using B3LYP/6-31G(d); experimentally this reaction gives both cycloadduct and copolymer. The concerted cycloaddition of cyclopentadiene with acrylonitrile is preferred computationally over the stepwise pathway by 5.9 kcal/mol; experimentally, only the Diels-Alder adduct is formed. For the reactions of (E)-1,3-pentadiene and acrylonitrile, both cycloaddition and copolymerization were observed experimentally; these trends were mimicked by the computational results, which showed only a 1.2 kcal/mol preference for the concerted pathway. For the reactions of (Z)-1,3-pentadiene and acrylonitrile, the stepwise pathway is preferred by 3.9 kcal/mol, in agreement with previous experimental findings that only polymerization occurs. M06-2X is known to give more accurate activation and reaction energetics but the energies of diradicals are too high. PMID:23758325

An Inventory of the Vascular Flora of Fort Greely, Interior Alaska

Science.gov (United States)

2001-02-01

Alnus tenuifolia Nutt. [= Alnus incana (L.) Moench ssp. tenuifolia (Nutt.) Breitung] Alnus viridis Vill. ssp. crispa (Ait.) A. Love & D. Love...Festuca rubra L., in part] Festuca saximontana Rydb. *Festuca vivipara (L.) Smith [= “Festuca vivipara”] Fragaria virginiana Duchesne ssp. glauca...tenuifolia (Nutt.) Breitung] Alnus viridis Vill. ssp. crispa (Ait.) A. Love & D. Love [= Alnus crispa (Ait.) Pursh ssp. crispa] Betula glandulosa Michx. Betula

Influence of primitive Biłgoraj horses on the glossy buckthorn (Frangula alnus)-dominated understory in a mixed coniferous forest

Science.gov (United States)

Klich, Daniel

2018-02-01

Changes in the understory dominated by glossy buckthorn Frangula alnus via the influence of primitive horses were analyzed in a 28-year-old enclosure in the village of Szklarnia at the Biłgoraj Horse-Breeding Centre near Janów Lubelski (eastern Poland). The analysis was conducted in 20 circular plots (30 m2) defined in adjacent, similar forest stands (enclosed and control). Disturbance by the horses, mainly through trampling, caused numerous paths to form within the glossy buckthorn-dominated understory and led to a decrease in density of stems of lower height classes (30-80 and 81-130 cm, respectively). An increase in species diversity at the expense of glossy buckthorn density was also observed. The horses' trampling caused an increase in Padus avium density and the encroachment of other woody plant species that were less shade-tolerant and grew well in soils rich in nutrients. An increase in the density of woody plants over 180 cm above ground was observed within the enclosure, which was probably the result of the horses' excretion of feces. The results presented here provide new insight into the ecological role that horses play in forest-meadow landscape mosaics, which, via altering the development of vegetation, may contribute to an increase in biodiversity within forest habitats.

Enantioselective Diels-Alder Reaction Using Chiral Mg Complexes Derived from Chiral 2-[2-[(Alkyl- or 2-[2-[(Arylsulfonyl)amino]phenyl]-4-phenyl-1,3-oxazoline.

Science.gov (United States)

Ichiyanagi, Tsuyoshi; Shimizu, Makoto; Fujisawa, Tamotsu

1997-11-14

Magnesium complexes derived from (R)-2-[2-[(alkyl- or (R)-2-[2-[(arylsulfonyl)amino]phenyl]-4-phenyl-1,3-oxazolines and methylmagnesium iodide were found to be efficient Lewis acid catalysts for the Diels-Alder reaction of 3-alkenoyl-1,3-oxazolidin-2-one with cyclopentadiene. Chiral ligands were easily prepared from readily available D-phenylglycinol in good yields. The reaction of 3-acryloyl-1,3-oxazolidin-2-one with cyclopentadiene catalyzed by a stoichiometric amount of the Lewis acid gave exclusively the endo-cycloaddition product in up to 92% ee. The sulfonamide group on the chiral ligand strongly influenced the enantiofacial selectivity: the use of a toluene-, benzene-, 1- or 2-naphthalene-, or methanesulfonamide group in the chiral ligand gave the endo-(2R)-cycloaddition product, while a trifluoromethanesulfonamide group predominantly gave its enantiomer, the endo-(2S)-cycloaddition product, in 65% ee. The scope and limitations of the catalytic effect of chiral Mg(II) complexes on the enantioselectivity of the Diels-Alder reaction were investigated. The reaction mechanism of the Mg(II)-catalyzed reaction is also discussed on the basis of the experimental results.

The Brønsted Acid-Catalyzed, Enantioselective Aza-Diels-Alder Reaction for the Direct Synthesis of Chiral Piperidones.

Science.gov (United States)

Weilbeer, Claudia; Sickert, Marcel; Naumov, Sergei; Schneider, Christoph

2017-01-12

We disclose herein the first enantioselective aza-Diels-Alder reaction of β-alkyl-substituted vinylketene silyl-O,O-acetals and imines furnishing a broad range of optically highly enriched 4-alkyl-substituted 2-piperidones. As a catalyst for this one-pot reaction we employed a chiral phosphoric acid which effects a vinylogous Mannich reaction directly followed by ring-closure to the lactam. Subsequent fully diastereoselective transformations including hydrogenation, enolate alkylation, and lactam alkylation/reduction processes converted the cycloadducts into various highly substituted piperidines of great utility for the synthesis of natural products and medicinally active compounds. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Classical Example of Total Kinetic and Thermodynamic Control: The Diels-Alder Reaction between DMAD and Bis-furyl Dienes.

Science.gov (United States)

Borisova, Kseniya K; Kvyatkovskaya, Elizaveta A; Nikitina, Eugeniya V; Aysin, Rinat R; Novikov, Roman A; Zubkov, Fedor I

2018-04-20

A rare example of chemospecificity in the tandem Diels-Alder reaction of activated alkynes and bis-dienes has been revealed. The reaction between bis-furyl dienes and DMAD occurs at 25-80 °C and leads to kinetically controlled "pincer" adducts, 4a,8a-disubstituted 1,4:5,8-diepoxynaphthalenes. On the contrary, only thermodynamically controlled "domino" adducts (2,3-disubstituted 1,4:5,8-diepoxynaphthalenes) are formed in the same reaction at 140 °C. The "pincer" adducts can be transformed to the "domino" adducts at heating. The rate constants for reactions of both types were calculated using dynamic 1 H NMR spectroscopy.

The Influence of Environmental Friendliness on Green Trust: The Mediation Effects of Green Satisfaction and Green Perceived Quality

Directory of Open Access Journals (Sweden)

Yu-Shan Chen

2015-07-01

Full Text Available As global green trends became more prevalent, green marketing also developed into an important issue. Although prior literature explored the main factors affecting green trust, it was inconclusive as to how environmental friendliness could affect the green trust in green marketing. This study aims to focus on the positive influence of environmental friendliness on green trust, and explore the mediation effects of green satisfaction and green perceived quality. This study undertakes an empirical study by means of questionnaire survey. The respondents are consumers who have experience purchasing green products. This study applies structural equation modeling (SEM to test the hypotheses. The findings of this study indicate that (1 environmental friendliness has a significant positive impact on green satisfaction, green perceived quality, and green trust; (2 both green satisfaction and green perceived quality positively affect green trust; and (3 green satisfaction and green perceived quality partially mediate the positive relationship between environmental friendliness and green trust.

Defining an adequate sample of earlywood vessels for retrospective injury detection in diffuse-porous species.

Directory of Open Access Journals (Sweden)

Estelle Arbellay

Full Text Available Vessels of broad-leaved trees have been analyzed to study how trees deal with various environmental factors. Cambial injury, in particular, has been reported to induce the formation of narrower conduits. Yet, little or no effort has been devoted to the elaboration of vessel sampling strategies for retrospective injury detection based on vessel lumen size reduction. To fill this methodological gap, four wounded individuals each of grey alder (Alnus incana (L. Moench and downy birch (Betula pubescens Ehrh. were harvested in an avalanche path. Earlywood vessel lumina were measured and compared for each tree between the injury ring built during the growing season following wounding and the control ring laid down the previous year. Measurements were performed along a 10 mm wide radial strip, located directly next to the injury. Specifically, this study aimed at (i investigating the intra-annual duration and local extension of vessel narrowing close to the wound margin and (ii identifying an adequate sample of earlywood vessels (number and intra-ring location of cells attesting to cambial injury. Based on the results of this study, we recommend analyzing at least 30 vessels in each ring. Within the 10 mm wide segment of the injury ring, wound-induced reduction in vessel lumen size did not fade with increasing radial and tangential distances, but we nevertheless advise favoring early earlywood vessels located closest to the injury. These findings, derived from two species widespread across subarctic, mountainous, and temperate regions, will assist retrospective injury detection in Alnus, Betula, and other diffuse-porous species as well as future related research on hydraulic implications after wounding.

1-acetylvinyl acrylates: new captodative olefins bearing an internal probe for the evaluation of the relative reactivity of captodative against electron-deficient double bonds in Diels-Alder and Friedel-Crafts reactions

International Nuclear Information System (INIS)

Herrera, Rafael; Universidad Michoacana de San Nicolas de Hidalgo, Morelia, Mich.; Jimenez-Vazquez, Hugo A.; Delgado, Francisco; Tamariz, Joaquin; Soederberg, Bjoern C.G.

2005-01-01

The captodative olefins 1-acetylvinyl esters of methacrylic and trans-crotonic acids, 3a and 3b, have been prepared. The presence of a second double bond in the molecule, acting as an internal probe, allowed us to compare their relative reactivity in Diels-Alder and Friedel-Crafts reactions. The reactivity was evaluated with cyclopentadiene (6) as diene in Diels-Alder cycloadditions, and with furan (9) and thiophene (10) as heteroaromatic Friedel-Crafts substrates. In both processes, the captodative enone double bond proved to be more reactive than that in the acrylic moiety. FMO theory accounted for this chemo selectivity as a consequence of the major π contribution of the enone to the LUMO of these molecules. The slight exo stereoselectivity observed in the cycloaddition to 6 parallels the higher stability of the corresponding transition state, according to the results of B3LYP/6-311G(d,p) calculations. (author)

Green power certification: environmental and consumer protection benefits of the Green-e programme

Energy Technology Data Exchange (ETDEWEB)

Wingate, M.; Hamrin, J. [Center for Resource Solutions (United States); Rabago, K. [Rocky Mountain Inst. (United States); Wiser, R. [Lawrence Berkeley National Lab. (United States)

2000-06-01

This article gives details of the Green-e environmental certification programme which certifies electricity generated from renewable energy sources in the US. This first non-profit certification programme originally was set up for California, and has now spread to other regions. The objectives of the Green-e programme, the need for the electricity product to meet minimum criteria to qualify, marketer requirements, verification of product claims, administration of the programme, and the second year programme results are discussed. The way in which the Green-e programme fits in with other programmes such as those set up by the state and federal customer protection agencies to help consumers select environmentally superior power is described.

The green building envelope : Vertical greening

NARCIS (Netherlands)

Ottelé, M.

2011-01-01

Planting on roofs and façades is one of the most innovative and fastest developing fields of green technologies with respect to the built environment and horticulture. This thesis is focused on vertical greening of structures and to the multi-scale benefits of vegetation. Vertical green can improve

GREEN MANAGEMENT: THE REALITY OF BEING GREEN IN BUSINESS

OpenAIRE

Tran, Ben

2009-01-01

Green management and going green are not as clear cut and easy as hyped by the general media. While going ecologically green is indeed beneficial and appropriate, the process and procedure of becoming green is anything but easy. Firstly, turning green is largely not a legal requirement, but a voluntary process. Thus, even though LEED (which is by far the more publicly known green certification standard) governs the certification of the green management effort, it is not a compulsory condition...

A Pyrene-Linked Cavity within a β-Barrel Protein Promotes an Asymmetric Diels-Alder Reaction.

Science.gov (United States)

Himiyama, Tomoki; Taniguchi, Naomasa; Kato, Shunsuke; Onoda, Akira; Hayashi, Takashi

2017-10-23

A unique π-expanded reaction cavity tethering a polycyclic moiety which provides a platform for substrate binding was constructed within the robust β-barrel structure of nitrobindin (NB). NB variants with cavities of different sizes and shapes are coupled with N-(1-pyrenyl)maleimide (Pyr) to prepare a series of NB-Pyr conjugates. The orientation of the pyrene moiety is fixed within the cavity by the coupling reaction. The fluorescent quenching analysis of NB-Pyr indicates that azachalcone (aza), which is a dienophile for a Diels-Alder (DA) reaction, is efficiently incorporated within the pyrene-linked reaction cavity by the aromatic interaction. The DA reaction between aza and cyclopentadiene proceeds within the reaction cavity of NB-Pyr in the presence of Cu II ion in high yield and high enantio- and regioselectivity. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

phenylalanine and l-tyrosine as chiral micellar media for the cat

African Journals Online (AJOL)

polar solvents [15-18]. Hence, surfactants offer the possibility for organic reactions to occur in aqueous media, and from the viewpoint of green chemistry, water is safer, harmless and environmentally benign [19]. However, there has been limited work on the use of chiral micellar media to catalyze Diels-. Alder reactions.

Syntheses of the Stemona Alkaloids (±)-Stenine, (±)-Neostenine, and (±)-13-Epineostenine Using a Stereodivergent Diels-Alder/Azido-Schmidt Reaction

Science.gov (United States)

Frankowski, Kevin J.; Golden, Jennifer E.; Zeng, Yibin; Lei, Yao; Aubé, Jeffrey

2009-01-01

A tandem Diels-Alder/azido Schmidt reaction sequence provides rapid access to the core skeleton shared by several Stemona alkaloids including stenine, neostenine, tuberstemonine, and neotubererostemonine. The discovery and evolution of inter- and intramolecular variations of this process and their applications to total syntheses of (±)–stenine and (±)–neostenine is described. The stereochemical outcome of the reaction depends on both substrate type and reaction condition, enabling the preparation of both (±)–stenine and (±)–neostenine from the same diene/dienophile combination. PMID:18396881

Diels-Alder Reactions of 12-Hydroxy-9(10®20-5aH-abeo-abieta-1(10,8(9,12(13-triene-11,14-dione

Directory of Open Access Journals (Sweden)

Shougang Hu

2013-06-01

Full Text Available 12-Hydroxy-9(10®20-5aH-abeo-abieta-1(10,8(9,12(13-triene-11,14-dione (quinone 2 served as the dienophile in numerous intermolecular Diels-Alder reactions. These cycloadditions were conducted either thermally (including microwave heating or with Lewis acid activation. While most dienes reacted with quinone 2 in good chemical yield, others were incompatible under the experimental conditions used.

Sustainable green urban planning: the Green Credit Tool

NARCIS (Netherlands)

Cilliers, E.J.; Diemont, E.; Stobbelaar, D.J.; Timmermans, W.

2010-01-01

Purpose – The Green Credit Tool is evaluated as a method to quantify the value of green-spaces and to determine how these green-space-values can be replaced or compensated for within urban spatial planning projects. Design/methodology/approach – Amersfoort Local Municipality created the Green Credit

Fungal Microbiomes Associated with Green and Non-Green Building Materials.

Science.gov (United States)

Coombs, Kanistha; Vesper, Stephen; Green, Brett J; Yermakov, Mikhail; Reponen, Tiina

2017-01-01

Water-damaged buildings can lead to fungal growth and occupant health problems. Green building materials, derived from renewable sources, are increasingly utilized in construction and renovations. However, the question as to what fungi will grow on these green compared to non-green materials, after they get wet, has not been adequately studied. By determining what fungi grow on each type of material, the potential health risks can be more adequately assessed. In this study, we inoculated green and non-green pieces of ceiling tile, composite board, drywall, and flooring with indoor dust containing a complex mixture of naturally occurring fungi. The materials were saturated with water and incubated for two months in a controlled environment. The resulting fungal microbiomes were evaluated using ITS amplicon sequencing. Overall, the richness and diversity of the mycobiomes on each pair of green and non-green pieces were not significantly different. However, different genera dominated on each type of material. For example, Aspergillus spp. had the highest relative abundance on green and non-green ceiling tiles and green composite boards, but Peniophora spp. dominated the non-green composite board. In contrast, Penicillium spp. dominated green and non-green flooring samples. Green gypsum board was dominated by Phialophora spp. and Stachybotrys spp., but non-green gypsum board by Myrothecium spp. These data suggest that water-damaged green and non-green building materials can result in mycobiomes that are dominated by fungal genera whose member species pose different potentials for health risks.

Determination of the suitability of chips from selected hardwoods for the production of furfural and charcoal. [Birches, beeches, oaks, alders

Energy Technology Data Exchange (ETDEWEB)

Piotrowski, Z

1979-01-01

Debarked, cut beech, birch, alder, and oak residues from forestry and woodworking operations contain 16.56-19.73% pentosans and as such can be used for hydrolysis to furfural (I). The hydrolytic residue (mostly lignocellulose) can be carbonized at 400 degrees to charcoal. The hydrolysis is carried out continuously with steam at 250-300 degrees and 1.18 MPa. The residue chips are first soaked in water at 90 degrees for 4 hours and then fed into the hydrolyzer countercurrently to the steam. The yields of I are 5-6% and the yields of charcoal are approximately 20% on the chip weight.

Artificial Metalloenzymes with the Neocarzinostatin Scaffold: Toward a Biocatalyst for the Diels-Alder Reaction.

Science.gov (United States)

Ghattas, Wadih; Cotchico-Alonso, Lur; Maréchal, Jean-Didier; Urvoas, Agathe; Rousseau, Maëva; Mahy, Jean-Pierre; Ricoux, Rémy

2016-03-02

A copper(II) cofactor coupled to a testosterone anchor, copper(II)-(5-(Piperazin-1-yl)-1,10-phenanthroline)testosterone-17-hemisuccinamide (10) was synthesized and associated with a neocarzinostatin variant, NCS-3.24 (KD =3 μm), thus generating a new artificial metalloenzyme by following a "Trojan horse" strategy. Interestingly, the artificial enzyme was able to efficiently catalyze the Diels-Alder cyclization reaction of cyclopentadiene (1) with 2-azachalcone (2). In comparison with what was observed with cofactor 10 alone, the artificial enzymes favored formation of the exo products (endo/exo ratios of 84:16 and 62:38, respectively, after 12 h). Molecular modeling studies assigned the synergy between the copper complex and the testosterone (KD =13 μm) moieties in the binding of 10 to good van der Waals complementarity. Moreover, by pushing the modeling exercise to its limits, we hypothesize on the molecular grounds that are responsible for the observed selectivity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Substituent effects on an inverse electron demand hetero Diels-Alder reaction in aqueous solution and organic solvents : Cycloaddition of substituted styrenes to di(2-pyridyl)-1,2,4,5-tetrazine

NARCIS (Netherlands)

Wijnen, Jan W.; Zavarise, Silvia; Engberts, Jan B.F.N.; Charton, Marvin

1996-01-01

The kinetics of the Diels-Alder reactions of di(2-pyridyl)-1,2,4,5-tetrazine (1) with substituted styrenes 2 was investigated in aqueous media and in organic solvents. The second-order rate constants ofthis reaction increase dramatically in water-rich media. A decrease in pH accelerates the aqueous

Diet preference of Eurasian Beaver (Castor Fiber L., 1758 in the environment of Oderské vrchy and its influence on the tree species composition of river bank stands

Directory of Open Access Journals (Sweden)

Jan Dvořák

2013-01-01

Full Text Available This paper deals with the dietary behaviour and the tree species preference in the river bank stands in the diet of established population Eurasian Beaver (Castor fiber L., 1758 in the environment of Oderské vrchy; the objective is to assess the suitability of this environment for future development of the Eurasian Beaver and to asses the influence of the beaver’s dietary behaviour on the river bank stands. In the monitored area, the total of 5 tree species with the following preference were recorded: willow (Salix 42.2%, aspen (Populus 28%, dogwood (Comus 15.5%, birch (Betula 7.4% and alder (Alnus 6.9%. The most damaged diameter interval recorded within the all damaged tree species ranges from 2.6 to 6 cm, followed by the interval 6.1–12 cm. Over 61% of the trees felled by the beaver had a bigger diameter. The most sensitive reaction to beaver’s dietary behaviour was shown by aspen (reduction of numbers by 27.6% and by willow (reduction of numbers by 16.6% on the monitored area.

Green Building Pro-Environment Behaviors: Are Green Users Also Green Buyers?

Directory of Open Access Journals (Sweden)

Xiaohuan Xie

2017-09-01

Full Text Available Pro-environment behaviors play a key role in advancing the development of green buildings. This study investigated the link between two green building pro-environment behaviors that require dissimilar resources: energy savings that do not require money in order to be more environmentally friendly and willingness to pay that involves economic resources including spending money in order to be more environmentally friendly. This study points out that the two pro-environment behaviors can be positively linked to each other. People who behave in an environmentally friendly manner at work would also be likely to pay an extra cost for a green building when buying a new home. The consistency of the two pro-environment behaviors can be explained by their common environmental beliefs: limits to growth and eco-crisis. The green building movement should prioritize pro-environmental behaviors and associated environmental beliefs to support green building policies, guidelines, and tools.

C—C bond formation in the intramolecular Diels-Alder reaction of triene amides

Directory of Open Access Journals (Sweden)

Abdelilah Benallou

2018-02-01

Full Text Available The mechanism nature of the intramolecular Diels–Alder reaction has been performed; and thus, the changes of C—C bond forming/breaking along IRC are characterized in this study. Conceptual DFT analyses of the most favorable adduct fused/exo shows that the flux electronic will take place from diene to dienophile moiety. Moreover, ELF topological analysis based on the electron density predicts that C—C bond is formed by the coupling of two pseudoradical centers generated at the most significant atoms of the molecules. However, C2 vs C3, also C1 and C4 interaction comes mainly from the global electron density transfer which takes place along the reaction. Two- stage one-step is the proposed mechanism of this reaction, the first stage aims for the formation of C2—C3 σ bond while the second stage aims for C1—C4 σ bond formation. Interestingly, the observed asynchronicity of this IMDA reaction due principally to the asymmetric reorganization of electron density at the most attractive centers.

C-C bond formation in the intramolecular Diels-Alder reaction of triene amides.

Science.gov (United States)

Benallou, Abdelilah; El Alaoui El Abdallaoui, Habib; Garmes, Hocine

2018-02-01

The mechanism nature of the intramolecular Diels-Alder reaction has been performed; and thus, the changes of C-C bond forming/breaking along IRC are characterized in this study. Conceptual DFT analyses of the most favorable adduct fused/exo shows that the flux electronic will take place from diene to dienophile moiety. Moreover, ELF topological analysis based on the electron density predicts that C-C bond is formed by the coupling of two pseudoradical centers generated at the most significant atoms of the molecules. However, C2 vs C3, also C1 and C4 interaction comes mainly from the global electron density transfer which takes place along the reaction. Two- stage one-step is the proposed mechanism of this reaction, the first stage aims for the formation of C2-C3 σ bond while the second stage aims for C1-C4 σ bond formation. Interestingly, the observed asynchronicity of this IMDA reaction due principally to the asymmetric reorganization of electron density at the most attractive centers.

Green thunderstorms

Science.gov (United States)

Gallagher, Frank Woolsey, III

Many people around the world have observed green light apparently emanating from severe thunderstorms, but until recently there has been no scientific study of the phenomenon. Green thunderstorms have been observed from time to time in association with deep convection or severe weather events. Some skeptics who have not personally observed a green thunderstorm suggest that they are some kind of illusion. The existence of green thunderstorms has been objectively demonstrated by recording spectra of light from thunderstorms using a handheld spectrophotometer. During the spring and summer of 1995 and the spring of 1996 numerous storms were observed and spectra of the light emanating from these storms were recorded. Observations were made both at the ground and aboard research aircraft. Furthermore, time series of spectra were recorded as the observed color of some storms changed from dark blue to a bluish-green. Several hypotheses have been advanced to explain the occurrence of green light in connection with severe storms. Fankhauser gave some observational support to the belief that green light from thunderstorms is possible and believed that the source of the light is from the blue sky penetrating thin regions in the clouds. Fraser believes that light from the setting sun, in combination with the process of scattering by atmospheric molecules, creates the green light associated with severe weather and the thunderstorm acts only as a black backdrop. Unfortunately, no cloud illuminated by the sun is black and the green airlight produced by the Fraser theory is in reality overwhelmed by light reflected by the cloud. Often the unusual coloration has been attributed to hail or to reflection of light from foliage on the ground. The quantitative measurements made during the observation period fail to support these assumptions. We have observed thunderstorms to be green over ground that was not green and we have observed blue thunderstorms over ground that was green

Organic chemistry of graphene: the Diels-Alder reaction.

Science.gov (United States)

Denis, Pablo A

2013-11-11

Herein, by using dispersion-corrected density functional theory, we investigated the Diels-Alder chemistry of pristine and defective graphene. Three dienes were considered, namely 2,3-dimethoxy-1,3-butadiene (DMBD), 9-methylanthracene (9MA), and 9,10-dimethylanthracene (910DMA). The dienophiles that were assayed were tetracyanoethylene (TCNE) and maleic anhydride (MA). When pristine graphene acted as the dienophile, we found that the cycloaddition products were 47-63 kcal mol(-1) less stable than the reactants, thus making the reaction very difficult. The presence of Stone-Wales translocations, 585 double vacancies, or 555-777 reconstructed double vacancies did not significantly improve the reactivity because the cycloaddition products were still located at higher energy than the reactants. However, for the addition of 910DMA to single vacancies, the product showed comparable stability to the separated reactants, whereas for unsaturated armchair edges the reaction was extremely favorable. With regards the reactions with dienophiles, for TCNE, the cycloaddition product was metastable. In the case of MA, we observed a reaction product that was less stable than the reactants by 50 kcal mol(-1) . For the reactions between graphene as a diene and the dienophiles, we found that the most-promising defects were single vacancies and unsaturated armchair edges, because the other three defects were much-less reactive. Thus, we conclude that the reactions with these above-mentioned dienes may proceed on pristine or defective sheets with heating, despite being endergonic. The same statement also applies to the dienophile maleic anhydride. However, for TCNE, the reaction is only likely to occur onto single vacancies or unsaturated armchair edges. We conclude that the dienophile character of graphene is slightly stronger than its behavior as a diene. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Green shipping management

CERN Document Server

Lun, Y H Venus; Wong, Christina W Y; Cheng, T C E

2016-01-01

This book presents theory-driven discussion on the link between implementing green shipping practices (GSP) and shipping firm performance. It examines the shipping industry’s challenge of supporting economic growth while enhancing environmental performance. Consisting of nine chapters, the book covers topics such as the conceptualization of green shipping practices (GSPs), measurement scales for evaluating GSP implementation, greening capability, greening and performance relativity (GPR), green management practice, green shipping network, greening capacity, and greening propensity. In view of the increasing quest for environment protection in the shipping sector, this book provides a good reference for firms to understand and evaluate their capability in carrying out green operations on their shipping activities.

Features of the Diels-Alder reaction between 9,10-diphenylanthracene and 4-phenyl-1,2,4-triazoline-3,5-dione

Science.gov (United States)

Kiselev, V. D.; Kornilov, D. A.; Kashaeva, E. A.; Potapova, L. N.; Krivolapov, D. B.; Litvinov, I. A.; Konovalov, A. I.

2014-12-01

The Diels-Alder reaction between substituted anthracenes 1a-1j and 4-phenyl-1,2,4-triazoline-3,5 ( 2) is studied. In all cases except one, the reaction proceeds on the most active 9,10-atoms of substituted anthracenes. The orthogonality of the two phenyl groups at the 9,10-position of diene 1a is found to shield 9,10-reactive centers. No dienophiles with C=C bonds are shown to participate in the Diels-Alder reaction with 1a; however, the reaction 1a + 2 proceeds with the very active dienophile 2,4-phenyl-1,2,4-triazoline-3,5-dione. It is shown that attachment occurs on the less active but sterically accessible 1,4-reactive center of diene 1a. The structure of adduct 3a is proved by 1H and 13C NMR spectroscopy and X-ray diffraction analysis. The following parameters are obtained for reaction 1a + 2 ⇆ 3a in toluene at 25°C: K eq = 2120 M-1, Δ Hf ≠ = 58.6 kJ/mol, Δ Sf ≠ = -97 J/(mol K), Δ Vf ≠ = -17.2 cm3/mol, Δ Hb ≠ = 108.8 kJ/mol, Δ Sb ≠ = 7.3 J/(mol K), Δ Vb ≠ = -0.8 cm3/mol, Δ H r-n = -50.2 kJ/mol, Δ S r-n = -104.3 J/(mol K), Δ V r-n = -15.6 cm3/mol. It is concluded that the values of equilibrium constants of the reactions 1a-1j + 2 ⇆ 3a-3j vary within 4 × 101-1011 M-1.

Foliar methyl salicylate emissions indicate prolonged aphid infestation on silver birch and black alder.

Science.gov (United States)

Blande, James D; Korjus, Minna; Holopainen, Jarmo K

2010-03-01

It is well documented that when plants are damaged by insects they respond by emitting a range of volatile organic compounds (VOCs). While there have been numerous reports concerning VOCs induced by chewing herbivores, there are relatively few studies detailing the VOCs induced by aphid feeding. The effects of aphid feeding on VOCs emitted by boreal forest trees have been particularly neglected. Herbivore-induced VOCs have relevance to direct and indirect plant defence and atmospheric chemistry. In this study, we analysed the VOCs emitted by Betula pendula (Roth) and Alnus glutinosa (L.) (Gaertn.) infested by specialist aphid species under laboratory conditions. We also complemented this by collecting VOCs from leaf beetle-damaged saplings under field conditions. In addition to induction of some inducible terpenes, we detected substantial aphid-induced emissions of methyl salicylate (MeSA) in both B. pendula and A. glutinosa. MeSA emission intensity depended on the length of aphid infestation. Feeding by beetles induced emission of (E)-DMNT in both tree species and (E)-beta-ocimene in A. glutinosa but had no effect on MeSA emissions. MeSA has been shown to have aphid-repellent qualities and has been shown recently to have impact on formation of secondary organic aerosols in the atmosphere. We discuss our results in relation to these two phenomena.

Green Consumerism : an Eco-Friendly Behaviour Form Through The Green Product Consumption and Green Marketing

Directory of Open Access Journals (Sweden)

Wiwik Handayani

2017-09-01

Full Text Available This research is referred to analyse the influence of consumer attitude of green product towards purchase intention. The consumer attitude of green product is a psychological tendencies that is expressed by evaluating a certain entity with some advantage or disadvantage considerations. The problem of this research is the low of cunsumer awareness to consume green product, because the lack to comprehend the importance of green product usage for health and eco-friendly. The purpose of this research is to test the influence of consumer attitude of green products towards purchase intention. Hypothesis testing using Partial Least Square (PLS. The result of analysis show that there is influence among consumer attitude of green product towards consumer purchase intention significantly.

Unfolding Green Defense

DEFF Research Database (Denmark)

Larsen, Kristian Knus

2015-01-01

In recent years, many states have developed and implemented green solutions for defense. Building on these initiatives NATO formulated the NATO Green Defence Framework in 2014. The framework provides a broad basis for cooperation within the Alliance on green solutions for defense. This report aims...... to inform and support the further development of green solutions by unfolding how green technologies and green strategies have been developed and used to handle current security challenges. The report, initially, focuses on the security challenges that are being linked to green defense, namely fuel...... consumption in military operations, defense expenditure, energy security, and global climate change. The report then proceeds to introduce the NATO Green Defence Framework before exploring specific current uses of green technologies and green strategies for defense. The report concludes that a number...

Metaphysical green

DEFF Research Database (Denmark)

Earon, Ofri

2011-01-01

example is a tiny Danish summer house from 1918 . The second example is ‘House before House’ , in Tokyo. The third example is a prefabricated house ‘CHU’ . The analysis evaluates the characteristics of diverse tones of green – from green image to green sensation. The analysis is based on the original...... of Sensation of Green is created by a physical interaction between the language of space and the language of nature” The notion of Sensation of Green was developed through a previous study ‘Learning from the Summer House’ investigating the unique architectural characteristics of the Danish summer houses...... the Sensation of Green? Three existing examples are agents to this discussion. The first example is a Danish summer house. The other two are international urban examples. While the summer house articulates the original meaning of Sensation of Green, the urban examples illustrate its urban context. The first...

The Influence of Consumers Perception of Green Products on Green Purchase Intention

OpenAIRE

Wilson Kong; Amran Harun; Rini Suryati Sulong; Jaratin Lily

2014-01-01

Green consumerism has increasingly received attention since the increased level of consumer awareness towards green products. Therefore, the aim of this paper had been to examine the influence of consumer perception of green products on green purchase intention. In this study, perception of green products was conceptualized as a multidimensional variable comprised of green corporate perception, eco-label, green advertising, green packaging, and green product value. By using a survey, a total ...

Higher-order human telomeric G-quadruplex DNA metalloenzymes enhance enantioselectivity in the Diels-Alder reaction.

Science.gov (United States)

Li, Yinghao; Jia, Guoqing; Wang, Changhao; Cheng, Mingpan; Li, Can

2015-03-02

Short human telomeric (HT) DNA sequences form single G-quadruplex (G4 ) units and exhibit structure-based stereocontrol for a series of reactions. However, for more biologically relevant higher-order HT G4 -DNAs (beyond a single G4 unit), the catalytic performances are unknown. Here, we found that higher-order HT G4 -DNA copper metalloenzymes (two or three G4 units) afford remarkably higher enantioselectivity (>90 % ee) and a five- to sixfold rate increase, compared to a single G4 unit, for the Diels-Alder reaction. Electron paramagnetic resonance (EPR) and enzymatic kinetic studies revealed that the distinct catalytic function between single and higher-order G4 -DNA copper metalloenzymes can be attributed to different Cu(II) coordination environments and substrate specificity. Our finding suggests that, like protein enzymes and ribozymes, higher-order structural organization is crucial for G4 -DNA-based catalysis. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Caracterización Física, Química y Mineralógica de Suelos con Vocación Forestal Protectora Región Andina Central Colombiana / Physical Chemical and Mineralogical Characterization of Soils with a Protective Forest Vocation, Central Andean Region of Colombia

Directory of Open Access Journals (Sweden)

Leyder Echeverri Tafur

2014-06-01

Full Text Available Resumen. En la Reserva Forestal Protectora Bosques de la CHEC, ubicada sobre la vertiente occidental de la cordillera central colombiana, municipios de Manizales y Villamaría, departamento de Caldas, se hizo la caracterización física, química y mineralógica de dos perfiles de suelos, descritos sobre dos laderas, con un manejo actual correspondiente a una plantación de aliso (Alnus acuminata y un bosque secundario. Los resultados permitieron establecer,desde el punto de vista físico, el dominio de clase textural areno francosa en la plantación de aliso y franco arenoso en el bosque secundario. Químicamente el suelo del perfil plantado con aliso, presentó valores de pH más bajos, mayor saturación de acidez intercambiable y menor saturación de bases en comparación con el perfil del bosque secundario. En ambos perfiles, el análisis óptico con microscopio petrográfico, permitió observar que los feldespatos, del grupo de las plagioclasas y el vidrio volcánico, se destacan como minerales abundantes en la fracción arena; mientras que en la fracción arcilla, el material no cristalino, seconsidera mineral predominante, seguido de la cristobalita y los feldespatos, según la metodología de difracción de rayos X. Se concluye que la vocación de uso forestal protector, bajo el cual se encuentran sometidos ambos suelos, es el más adecuado, teniendo en cuenta que las limitaciones químicas, dificultan el establecimiento de sistemas de producción agropecuaria. / Abstract. The physical, chemical and mineralogical characterization of two soil profiles on two slopes, with a management currently corresponding to an Andean alder plantation (Alnus acuminata and a secondary forest, was carried out at the Protective Forest Reserve of the CHEC. This reserve is located on the western slope of the Central Mountain Range of the Colombian Andes, in the municipalities of Manizales and Villamaria, Caldas Department. The results

Green Tourism

OpenAIRE

Hasan, Ali

2014-01-01

Green tourism is defined as environmentally friendly tourism activities with various focuses and meanings. In a broad term, green tourism is about being an environmentally friendly tourist or providing environmentally friendly tourist services. The green tourism concept would be highly appealing to tourism enterprises and operators owing to increasing governmental pressure to improve environmental performance by adopting effective and tangible environmental management techniques. Green to...

[3+2] Cycloaddition of propargylic alcohols and α-oxo ketene dithioacetals: synthesis of functionalized cyclopentadienes and further application in a Diels-Alder reaction.

Science.gov (United States)

Fang, Zhongxue; Liu, Jianquan; Liu, Qun; Bi, Xihe

2014-07-07

Cyclopentadienes are valuable intermediates in organic synthesis and also ubiquitous as the Cp ligands in organometallic chemistry. As part of ongoing efforts to develop novel organic reactions that employ functionalized alkynes, a [3+2] cycloaddition of propargylic alcohols and ketene dithioacetals has been developed, which leads to fully substituted 2,5-dialkylthio cyclopentadienes in good to excellent yields. In an unusual dethiolating Diels-Alder reaction, the cyclopentadienes were further reacted with maleimides to afford a family of novel fluorescent polycyclic compounds. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Holocene environmental changes in southern Kamchatka, Far Eastern Russia, inferred from a pollen and testate amoebae peat succession record

Science.gov (United States)

Klimaschewski, A.; Barnekow, L.; Bennett, K. D.; Andreev, A. A.; Andrén, E.; Bobrov, A. A.; Hammarlund, D.

2015-11-01

High resolution palaeoenvironmental records in Far-Eastern Russia are rare, and the Kamchatka Peninsula is among the least studied areas of the region. This paper describes a record spanning the last ca. 11,000 yr, obtained from a bog in the southern part of Kamchatka. The radiocarbon dated core was analysed for pollen, testate amoebae, charcoal and loss-on-ignition (LOI). The vegetation during the early Holocene was dominated by grasses (Poaceae), birch (Betula) and heath (Ericaceae p. p.). Around 10,300 cal yr BP there was a substantial change in the vegetation cover to shrub alder (Alnus viridis s.l.) stands with sedges and ferns (Polypodiophyta) as well as herbs such as meadow rue (Thalictrum) in the understory. In the surroundings of Utka peatlands started to form. The variations in the vegetation cover were most probably caused by climatic changes. At the beginning of sediment accumulation, before 10,300 cal yr BP, the composition of the vegetation points to cooler summers and/or decreased annual precipitation. Around 10,300 cal yr BP, changes in vegetation occurred due to rising temperatures and/or changed water regimes. Increased abundancies of dry indicating testate amoebae after 9100 cal yr BP point to intermediate to dry soil conditions. Between 8600 and 7700 cal yr BP tree alder (Alnus incana) was widely spread at the site which probably indicates optimal environmental conditions. The tephra layer at 381-384.5 cm (ca. 8500 cal yr BP) produces a strong impact on the testate amoebae assemblages. At 7700 cal yr BP there was a sudden drop of A. incana in the local vegetation. From this time on, A. incana and also A. viridis decrease continuously whereas Betula gradually increases. The upper part of the sequence (after 6300 cal yr BP) shows higher abundancies of meadowsweet (Filipendula) and sweet gale (Myrica) pollen. After 6300 cal yr BP, changes in testate amoebae demonstrate variable soil moisture conditions at the site. Between 3700 and 1800 cal yr BP

Green roofs and the LEED green building rating system

Energy Technology Data Exchange (ETDEWEB)

Kula, R. [Sustainable Solutions Inc., Wagoner, OK (United States)

2005-07-01

The sustainable building industry is becoming increasingly aware of the host of public and private benefits that green roofs can provide in built environments. In dense urban environments, green roofs function to reduce stormwater runoff, urban heat island effects, and particulate matter (PM) pollution. The emerging green roof industry is now poised to support the efforts of green building networks in North America. This paper discussed the general benefits of green roofs, and their recognition within the Leadership in Energy and Environmental Design (LEED) Green Building Rating System. A case study of Mountain Equipment Co-op's Winnipeg site was presented. The building's green roof was directly responsible for earning 5 credits and contributing to the achievement of an additional 2 credits under the LEEDS certification process. Credits were earned for reduced site disturbance; landscape design to reduce heat islands; and water efficiency. The green roof at the site provided the vast majority of the building's cooling needs through an evaporative cooling trough. A photovoltaic pump was used to feed the building's irrigation system, as well as to pump ground water through cooling valances. It was concluded that the rise of sustainable building practices and the LEED Green Building Rating System will revolutionize the way new buildings are constructed.

Green Consumerism : an Eco-Friendly Behaviour Form Through The Green Product Consumption and Green Marketing

OpenAIRE

Handayani, Wiwik

2017-01-01

This research is referred to analyse the influence of consumer attitude of green product towards purchase intention. The consumer attitude of green product is a psychological tendencies that is expressed by evaluating a certain entity with some advantage or disadvantage considerations. The problem of this research is the low of cunsumer awareness to consume green product, because the lack to comprehend the importance of green product usage for health and eco-friendly. The purpose of this rese...

An MM and QM Study of Biomimetic Catalysis of Diels-Alder Reactions Using Cyclodextrins

Directory of Open Access Journals (Sweden)

Wei Chen

2018-01-01

Full Text Available We performed a computational investigation of the mechanism by which cyclodextrins (CDs catalyze Diels-Alder reactions between 9-anthracenemethanol and N-cyclohexylmaleimide. Hydrogen bonds (Hbonds between N-cyclohexylmaleimide and the hydroxyl groups of cyclodextrins were suggested to play an important role in this catalytic process. However, our free energy calculations and molecular dynamics simulations showed that these Hbonds are not stable, and quantum mechanical calculations suggested that the reaction is not promoted by these Hbonds. The binding of 9-anthracenemethanol and N-cyclohexylmaleimide to cyclodextrins was the key to the catalytic process. Cyclodextrins act as a container to hold the two reactants in the cavity, pre-organize them for the reactions, and thus reduce the entropy penalty to the activation free energy. Dimethyl-β-CD was a better catalyst for this specific reaction than β-CD because of its stronger van der Waals interaction with the pre-organized reactants and its better performance in reducing the activation energy. This computational work sheds light on the mechanism of the catalytic reaction by cyclodextrins and introduces new perspectives of supramolecular catalysis.

Random quaternary ammonium Diels-Alder poly(phenylene) copolymers for improved vanadium redox flow batteries

Science.gov (United States)

Largier, Timothy D.; Cornelius, Chris J.

2017-06-01

This study analyzes the effect of quaternary ammonium homopolymer (AmPP) and ionic and non-ionic random unit copolymerization (AmPP-PP) of Diels-Alder poly(phenylene)s on electrochemical and transport properties, vanadium redox flow battery performance, and material stability. AmPP-PP materials were synthesized with IEC's up to 2.2 meq/g, displaying a carbonate form ion conductivity of 17.3 mS/cm and water uptake of 57.3%. Vanadium ion permeability studies revealed that the random copolymers possess superior charge carrier selectivity. For materials of comparable ion content, at 10 mA/cm2 the random copolymer displayed a 14% increase in coulombic efficiency (CE) corresponding to a 7% increase in energy efficiency. All quaternary ammonium materials displayed ex situ degradation in a 0.5 M V5+ + 5 M H2SO4 solution, with the rate of degradation appearing to increase with IEC. Preliminary studies reveal that the neutralizing counter-ion has a significant effect on VRB performance, proportional to changes in vanadium ion molecular diffusion.

Green power programs in Canada : 2003 : overview of Government green power policies, utility green power implementation initiatives, green power and certificate marketing programs, and their benefits

International Nuclear Information System (INIS)

Whitmore, J.; Bramley, M.; Holmes, R.

2004-09-01

Green power is defined as electricity produced from renewable sources, and whose production has low adverse impacts on the environment, human health and communities. Green power has near-zero greenhouse gas (GHG) emissions and includes sources such as wind, hydro, and solar power. It offers several environmental benefits, as well as the enhancement of energy security, regional development, economic diversification and the creation of skilled jobs. There are four categories of programs related to green power development in Canada: government green power policies, utility green power development programs, green power marketing initiatives, and green power certificate marketing initiatives. Most of the activities in Canada associated with these four categories in 2003 were discussed in this report. However, difficulties with quantification prevented the inclusion of some green power activities such as (1) the generation of green power not certified or identified by the generator as green power, (2) industry or residential self-generation, (3) net metering, and (4) small government programs. Green power generation facilities in 2003 totaled 775 MW of capacity compared to 539 MW in 2002. Hydro capacity represented 41 per cent, followed by wind capacity at 40 per cent and wood waste at 17 per cent. Most of the green power generation facilities in 2003 were located in Alberta, followed by British Columbia, Ontario and Quebec. 230 refs., 8 tabs., 1 fig

Surface confined retro Diels-Alder reaction driven by the swelling of weak polyelectrolytes.

Science.gov (United States)

Lyu, Beier; Cha, Wenli; Mao, Tingting; Wu, Yuanzi; Qian, Hujun; Zhou, Yitian; Chen, Xiuli; Zhang, Shen; Liu, Lanying; Yang, Guang; Lu, Zhongyuan; Zhu, Qiang; Ma, Hongwei

2015-03-25

Recently, the type of reactions driven by mechanical force has increased significantly; however, the number of methods for activating those mechanochemical reactions stays relatively limited. Furthermore, in situ characterization of a reaction is usually hampered by the inherent properties of conventional methods. In this study, we report a new platform that utilizes mechanical force generated by the swelling of surface tethered weak polyelectrolytes. An initiator with Diels-Alder (DA) adduct structure was applied to prepare the polyelectrolyte-carboxylated poly(OEGMA-r-HEMA), so that the force could trigger the retro DA reaction. The reaction was monitored in real time by quartz crystal microbalance and confirmed with atomic force microscopy and X-ray photoelectron spectroscopy. Compared with the conventional heating method, the swelling-induced retro DA reaction proceeded rapidly with high conversion ratio and selectivity. A 23.61 kcal/mol theoretical energy barrier supported the practicability of this retro DA reaction being triggered mechanically at ambient temperature. During swelling, the tensile force was controllable and persistent. This unique feature imparts this mechanochemical platform the potential to "freeze" an intermediate state of a reaction for in situ spectroscopic observations, such as surface-enhanced Raman spectroscopy and frequency generation spectroscopy.

Liquid-Crystalline Ionic Liquids as Ordered Reaction Media for the Diels-Alder Reaction.

Science.gov (United States)

Bruce, Duncan W; Gao, Yanan; Canongia Lopes, José Nuno; Shimizu, Karina; Slattery, John M

2016-11-02

Liquid-crystalline ionic liquids (LCILs) are ordered materials that have untapped potential to be used as reaction media for synthetic chemistry. This paper investigates the potential for the ordered structures of LCILs to influence the stereochemical outcome of the Diels-Alder reaction between cyclopentadiene and methyl acrylate. The ratio of endo- to exo-product from this reaction was monitored for a range of ionic liquids (ILs) and LCILs. Comparison of the endo:exo ratios in these reactions as a function of cation, anion and liquid crystallinity of the reaction media, allowed for the effects of liquid crystallinity to be distinguished from anion effects or cation alkyl chain length effects. These data strongly suggest that the proportion of exo-product increases as the reaction media is changed from an isotropic IL to a LCIL. A detailed molecular dynamics (MD) study suggests that this effect is related to different hydrogen bonding interactions between the reaction media and the exo- and endo-transition states in solvents with layered, smectic ordering compared to those that are isotropic. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Green power programs in Canada : 2002 : Overview of Government green power policies, utility green power development programs, green power and certificate marketing initiatives, and their benefits

International Nuclear Information System (INIS)

Bramley, M.; Boustie, S.; Vadgama, J.; Wieler, C.; Pape-Salmon, A.; Holmes, R.

2003-11-01

Green power is generally defined as electricity produced from renewable sources, and whose production has low adverse impacts on the environment, human health and communities. Green power has near-zero greenhouse gas (GHG) emissions and includes sources such as wind, hydro, and solar power. Green power offers several environmental benefits, as well as the enhancement of energy security, regional development, economic diversification and the creation of skilled jobs. There are four categories of programs related to green power development in Canada: government green power policies, utility green power development programs, green power marketing initiatives, and green power certificate marketing initiatives. Most of the activities associated with these four categories in 2002 were discussed in this report. However, difficulties with quantification prevented the inclusion of some green power activities in the report, such as (1) the generation of green power not certified or identified by the generator as green power, (2) industry or residential self-generation, (3) net metering, and (4) small government programs. Each category was presented in detail. The information included in the report was based on surveys sent to each program proponent. Follow-up communications and other publicly available information was also included. New programs operating in 2003 or currently under development were listed. refs., 8 tabs

The Green Experiment: Cities, Green Stormwater Infrastructure, and Sustainability

Directory of Open Access Journals (Sweden)

Christopher M. Chini

2017-01-01

Full Text Available Green infrastructure is a unique combination of economic, social, and environmental goals and benefits that requires an adaptable framework for planning, implementing, and evaluating. In this study, we propose an experimental framework for policy, implementation, and subsequent evaluation of green stormwater infrastructure within the context of sociotechnical systems and urban experimentation. Sociotechnical systems describe the interaction of complex systems with quantitative and qualitative impacts. Urban experimentation—traditionally referencing climate change programs and their impacts—is a process of evaluating city programs as if in a laboratory setting with hypotheses and evaluated results. We combine these two concepts into a singular framework creating a policy feedback cycle (PFC for green infrastructure to evaluate municipal green infrastructure plans as an experimental process within the context of a sociotechnical system. After proposing and discussing the PFC, we utilize the tool to research and evaluate the green infrastructure programs of 27 municipalities across the United States. Results indicate that green infrastructure plans should incorporate community involvement and communication, evaluation based on project motivation, and an iterative process for knowledge production. We suggest knowledge brokers as a key resource in connecting the evaluation stage of the feedback cycle to the policy phase. We identify three important needs for green infrastructure experimentation: (i a fluid definition of green infrastructure in policy; (ii maintenance and evaluation components of a green infrastructure plan; and (iii communication of the plan to the community.

Metaphysical green

OpenAIRE

Earon, Ofri

2011-01-01

“Sensation of Green is about the mental process like touching, seeing, hearing, or smelling, resulting from the immediate stimulation of landscape forms, plants, trees, wind and water. Sensation of Green triggers a feeling of scale, cheerfulness, calmness and peace. The spatial performance of Sensation of Green is created by a physical interaction between the language of space and the language of nature” The notion of Sensation of Green was developed through a previous study ‘Learning from th...

Green corridors basics

DEFF Research Database (Denmark)

Panagakos, George

2016-01-01

SuperGreen project, which aimed at advancing the green corridor concept through a benchmarking exercise involving Key Performance Indicators (KPIs). The chapter discusses the available definitions of green corridors and identifies the characteristics that distinguish a green corridor from any other...... efficient surface transportation corridor. After providing examples of green corridor projects in Europe, it focuses on the KPIs that have been proposed by various projects for monitoring the performance of a freight corridor. Emphasis is given to the SuperGreen KPIs, covering the economic, technical...

Synthesis of Unsymmetrical Annulated 2,2’-Bipyridine Analogues with Attached Cycloalkene and Piperidine Rings via Sequential Diels-Alder Reaction of 5,5’-bi-1,2,4-triazinesâ€

Directory of Open Access Journals (Sweden)

D. Branowska

2005-12-01

Full Text Available Synthesis of bisfunctionalized unsymmetrical 2,2’-bipyridines 8 or their sulfonyl derivatives 12a,b are described. They were prepared via the Diels-Alder reaction of 1-methyl-4-pyrrolidin-1-yl-1,2,3,6-tetrahydropyridine (6 with 3,3’-bis(methyl- sulfanyl-5,5’-bi-1,2,4-triazine (1. The reaction leads to the single cycloaddition product 7 which undergoes Diels-Alder reaction with cyclic enamines 2a,b to give unsymmetrical 2,2’-bipyridine derivatives 8, consisting of the two different heterocyclic units: cycloalkeno[c]pyridine and 2,6-naphthyridine.

Green Thunderstorms Observed.

Science.gov (United States)

Gallagher, Frank W., III; Beasley, William H.; Bohren, Craig F.

1996-12-01

Green thunderstorms have been observed from time to time in association with deep convection or severe weather events. Often the green coloration has been attributed to hail or to reflections of light from green foliage on the ground. Some skeptics who have not personally observed a green thunderstorm do not believe that green thunderstorms exist. They suggest that the green storms may be fabrications by excited observers. The authors have demonstrated the existence of green thunderstorms objectively using a spectrophotometer. During the spring and summer of 1995 the authors observed numerous storms and recorded hundreds of spectra of the light emanating corn these storms. It was found that the subjective judgment of colors can vary somewhat between observers, but the variation is usually in the shade of green. The authors recorded spectra of green and nongreen thunderstorms and recorded spectral measurements as a storm changed its appearance from dark blue to a bluish green. The change in color is gradual when observed from a stationary position. Also, as the light from a storm becomes greener, the luminance decreases. The authors also observed and recorded the spectrum of a thunderstorm during a period of several hours as they flew in an aircraft close to a supercell that appeared somewhat green. The authors' observations refute the ground reflection hypothesis and raise questions about explanations that require the presence of hail.

Novel Diels-Alder based self-healing epoxies for aerospace composites

Science.gov (United States)

Coope, T. S.; Turkenburg, D. H.; Fischer, H. R.; Luterbacher, R.; van Bracht, H.; Bond, I. P.

2016-08-01

Epoxy resins containing Diels-Alder (DA) furan and maleimide moieties are presented with the capability to self-heal after exposure to an external heat source. A conventional epoxy amine system has been combined with furfuryl and maleimide functional groups in a two-step process, to avoid major side-reactions, and the concentration of a thermo-reversibly binding cross-linker was considered to balance thermoset and thermoplastic behaviours, and the subsequent self-healing performance. In the context of self-repair technologies an inbuilt ‘intrinsic’ self-healing system is deemed favourable as the healing agent can be placed in known ‘hot spot’ regions (i.e. skin-stringer run outs, ply drops and around drilled holes) where operational damage predominately occurs in load bearing aerospace structures. In this study, the mechanical and self-healing performance of furan functionalised epoxy resins containing varying amounts (10, 20, 30 or 40 pph) of bismaleimide were investigated using a bulk epoxy polymer tapered double cantilever beam test specimen geometry. Two forms, a thin film and a bulk material, were evaluated to account for future integration methods into fibre reinforced polymer (FRP) composites. The highest healing efficiency, with respect to the obtained initial load value, was observed from the 20 pph bulk material derivative. The polymers were successful in achieving consistent multiple (three) healing cycles when heated at 150 °C for 5 min. This novel investigated DA material exhibits favourable processing characteristics for FRP composites as preliminary studies have shown successful coextrution with reinforcing fibres to form free standing films and dry fibre impregnation.

The Influence of Green Marketing on Green Satisfaction Mediated By Perceived Quality and Its Impact to Green Trust in Injection Motorcycle

Directory of Open Access Journals (Sweden)

Shelvy Kurniawan

2014-09-01

Full Text Available Currently, motorcycle manufacturers are increasingly motivated to replace their motorcycle into fuel injection products. The growing concern from the consumers to the environment and the regulations of emission standards, that is Euro 3, for motorcycle industry is being finalized in the Ministry of Environment in order to be implemented in Indonesia. Through this research, the writer will examine the effect of green marketing on perceived quality, green satisfaction, and green trust, the effect of perceived quality on green satisfaction, and the effect of green satisfaction on green trust. Those effects needs to be investigated in order to know how far the effects of green marketing and to ensure whether green marketing is well accepted or not by the market in motorcycle industry. Scope of this research is also limited to the user of fuel injection motorcycle in Jakarta for Honda and Yamaha who involved as decision maker when the motorcycle is purchased. Sampling technique used in this research is quota sampling and the analysis method is structural equation modeling (SEM. The findings of this research are: green marketing has a significant direct effect on perceived quality, perceived quality has a significant direct effect on green satisfaction, green satisfaction has a significant direct effect on green trust, green marketing has a significant direct and indirect effect on green satisfaction, and green marketing has a significant direct and indirect effect on green trust. All of those effects are found to be positive effects.

Purchasing green to become greener: Factors influence consumers’ green purchasing behavior

Directory of Open Access Journals (Sweden)

Hosein Vazifehdoust

2013-09-01

Full Text Available This study proposes an integrated model that combines the Theory of Reasoned Action (TRA and two categories of variables, personal and marketing, to investigate the attitudinal and behavioral decision factors to purchase green products. The model derived and tested via structural equation modeling on a sample of 374 consumers from the Guilan province in Iran. The results show that attitude is explained by consumers’ environmental concern, quality of green products, green advertising and green labeling. The results of the structural equation analysis indicate that attitude positively influences intention to purchase green products. Green purchasing intention also influences on green purchasing behavior. This paper also discusses the implications of the results for marketers and researchers.

Flash-flood impacts cause changes in wood anatomy of Alnus glutinosa, Fraxinus angustifolia and Quercus pyrenaica.

Science.gov (United States)

Ballesteros, J A; Stoffel, M; Bollschweiler, M; Bodoque, J M; Díez-Herrero, A

2010-06-01

Flash floods may influence the development of trees growing on channel bars and floodplains. In this study, we analyze and quantify anatomical reactions to wounding in diffuse-porous (Alnus glutinosa L.) and ring-porous (Fraxinus angustifolia Vahl. and Quercus pyrenaica Willd.) trees in a Mediterranean environment. A total of 54 cross-sections and wedges were collected from trees that had been injured by past flash floods. From each of the samples, micro-sections were prepared at a tangential distance of 1.5 cm from the injury to determine wounding-related changes in radial width, tangential width and lumen of earlywood vessels, and fibers and parenchyma cells (FPC). In diffuse-porous A. glutinosa, the lumen area of vessels shows a significant (non-parametric test, P-value <0.05) decrease by almost 39% after wounding. For ring-porous F. angustifolia and Q. pyrenaica, significant decreases in vessel lumen area are observed as well by 59 and 42%, respectively. Radial width of vessels was generally more sensitive to the decrease than tangential width, but statistically significant values were only observed in F. angustifolia. Changes in the dimensions of earlywood FPC largely differed between species. While in ring-porous F. angustifolia and Q. pyrenaica the lumen of FPC dropped by 22 and 34% after wounding, we observed an increase in FPC lumen area in diffuse-porous A. glutinosa of approximately 35%. Our data clearly show that A. glutinosa represents a valuable species for flash-flood research in vulnerable Mediterranean environments. For this species, it will be possible in the future to gather information on past flash floods with non-destructive sampling based on increment cores. In ring-porous F. angustifolia and Q. pyrenaica, flash floods leave less drastic, yet still recognizable, signatures of flash-flood activity through significant changes in vessel lumen area. In contrast, the use of changes in FPC dimensions appears less feasible for the determination of

Is 'green finance' actually green? 'Make The Planet Great Again' or 'Green-washing', we must choose. Report on green bonds and climate bonds

International Nuclear Information System (INIS)

Combes, Maxime; Plihon, Dominique; Zippert, Jean-Sebastien; Chaussalet, Alexis; Planche, Jeanne; Poulain, Melanie

2017-12-01

As Paris dreams of becoming the capital of green finance, the author proposes a discussion of the emerging market of green bonds, and formulates a set of recommendations for this new financial instrument not to be polluted by green-washing operations. He first describes what a green bond is, and then comments what the green bond market represents, discusses development perspectives for this market, comments the Paris dream of becoming the world capital of a green and sustainable finance. He explains why this green bond market appears to be so interesting, and what guarantees that a green bond will finance green projects. He discusses the role of rating agencies, whether the emitter of a green bond must be green, and the impact of green bonds on climate, on the environment and on populations. He discusses the possible evolution towards a constraining regulation, and examines whether this system can be an operational financing source for energy transition. Recommendations concern the market regulation by public authorities, the creation of a new rating agency for green finance, how to make the world bond market climate-compatible, and the creation of other financing channels for actors who have no access to the bond market

Green industrial policy

OpenAIRE

Dani Rodrik

2014-01-01

Green growth requires green technologies: production techniques that economize on exhaustible resources and emit fewer greenhouse gases. The availability of green technologies both lowers social costs in the transition to a green growth path and helps achieve a satisfactory rate of material progress under that path. The theoretical case in favour of using industrial policy to facilitate green growth is quite strong. Economists’ traditional scepticism on industrial policy is grounded instead o...

Thermodynamic and molecular origin of interfacial rate enhancements and endo-selectivities of a Diels-Alder reaction.

Science.gov (United States)

Beniwal, Vijay; Kumar, Anil

2017-02-08

Organic reactions in general display large rate accelerations when performed under interfacial conditions, such as on water or at ionic liquid interfaces. However, a clear picture of the physicochemical factors responsible for this large rate enhancements is not available. To gain an understanding of the thermodynamic and molecular origin of these large rate enhancements, we performed a Diels-Alder reaction between cyclopentadiene and methyl acrylate at ionic liquid/n-hexane interfaces. This study describes, for the first time, a methodology for the calculation of the activation parameters of an interfacial reaction. It has been seen that the energy of activation for an interfacial reaction is much smaller than that of the corresponding homogeneous reaction, resulting into the large rate acceleration for the interfacial reaction. Furthermore, the study describes the effects of the alkyl chain length of ionic liquid cations, the extent of heterogeneity, and the polarity of ionic liquids on the rate constants and stereoselectivity of the reaction.

Effects of elevated carbon dioxide concentration on growth and nitrogen fixation in Alnus glutinosa in a long-term field experiment

Energy Technology Data Exchange (ETDEWEB)

Temperton, V. M.; Jackson, G.; Barton, C. V. M.; Jarvis, P. G. [Edinburgh Univ., Inst. of Ecology and Resource Management, Edinburgh (United Kingdom); Grayston, S. J. [Macaulay Land Use Research Inst., Plant-Soil Interaction Group, Aberdeen (United Kingdom)

2003-10-01

Total biomass, relative growth rate, net assimilation rate, leaf area and net photosynthetic rate of nitrogen-fixing were measured in common alder trees, grown for three years in open-top chambers in the presence of either ambient or elevated atmospheric carbon dioxide, and in two soil nitrogen regimes: i.e. full nutrient solution or no fertilizer. The objective was to clarify the relationship between elevated carbon dioxide and the rate of nitrogen fixation of nodulated trees growing under field conditions. Results showed that growth in elevated carbon dioxide stimulated net photosynthesis and total biomass accumulation. However, relative growth rate was not significantly affected by elevated carbon dioxide. Leaf area and leaf phosphorus concentration were also unaffected. Nodule mass on roots of unfertilized trees exposed to elevated carbon dioxide increased, compared with fertilized trees exposed to ambient carbon dioxide levels. Since neither in the fertilized, nor the unfertilized trees was there any evidence of effects on growth, biomass and photosynthesis that could be attributed to the interaction of fertilizer and elevated carbon dioxide interaction, it was concluded that both types exhibit similar carbon dioxide-induced growth and photosynthetic enhancements. 40 refs., 5 tabs., 3 figs.

Effects of elevated carbon dioxide concentration on growth and nitrogen fixation in Alnus glutinosa in a long-term field experiment

International Nuclear Information System (INIS)

Temperton, V. M.; Jackson, G.; Barton, C. V. M.; Jarvis, P. G.; Grayston, S. J.

2003-01-01

Total biomass, relative growth rate, net assimilation rate, leaf area and net photosynthetic rate of nitrogen-fixing were measured in common alder trees, grown for three years in open-top chambers in the presence of either ambient or elevated atmospheric carbon dioxide, and in two soil nitrogen regimes: i.e. full nutrient solution or no fertilizer. The objective was to clarify the relationship between elevated carbon dioxide and the rate of nitrogen fixation of nodulated trees growing under field conditions. Results showed that growth in elevated carbon dioxide stimulated net photosynthesis and total biomass accumulation. However, relative growth rate was not significantly affected by elevated carbon dioxide. Leaf area and leaf phosphorus concentration were also unaffected. Nodule mass on roots of unfertilized trees exposed to elevated carbon dioxide increased, compared with fertilized trees exposed to ambient carbon dioxide levels. Since neither in the fertilized, nor the unfertilized trees was there any evidence of effects on growth, biomass and photosynthesis that could be attributed to the interaction of fertilizer and elevated carbon dioxide interaction, it was concluded that both types exhibit similar carbon dioxide-induced growth and photosynthetic enhancements. 40 refs., 5 tabs., 3 figs

Green consumerism

DEFF Research Database (Denmark)

de Groot, Judith I.M.; Schuitema, Geertje; Garson, Carrie Lee

and biospheric values influence the importance of such ‘green’ product characteristics on purchasing intentions. In two within-subjects full-factorial experimental studies (N = 100 and N = 107), we found that purchase intentions of products were only steered by green characteristics if prices were low...... and the brand was familiar. Green product characteristics did not influence purchase intentions at all when these proself product characteristics were not fulfilled (i.e., high prices and unfamiliar brands). The importance of proself and green product characteristics on purchasing intentions was also......Our presentation will focus on the influence of product characteristics and values on green consumerism. Although generally a majority of consumers support the idea of purchasing green products, we argue, based on social dilemma theory, that proself product characteristics and egoistic...

Soil aggregation and slope stability related to soil density, root length, and mycorrhiza

Science.gov (United States)

Graf, Frank; Frei, Martin

2013-04-01

Eco-engineering measures combine the use of living plants and inert mechanical constructions to protect slopes against erosion and shallow mass movement. Whereas in geotechnical engineering several performance standards and guidelines for structural safety and serviceability of construction exist, there is a lack of comparable tools in the field of ecological restoration. Various indicators have been proposed, including the fractal dimension of soil particle size distribution, microbiological parameters, and soil aggregate stability. We present results of an soil aggregate stability investigation and compare them with literature data of the angle of internal friction ?' which is conventionally used in slope stability analysis and soil failure calculation. Aggregate stability tests were performed with samples of differently treated moraine, including soil at low (~15.5 kN/m³) and high (~19.0 kN/m³) dry unit weight, soil planted with Alnus incana (White Alder) as well as the combination of soil planted with alder and inoculated with the mycorrhizal fungus Melanogaster variegatus s.l. After a 20 weeks growth period in a greenhouse, a total of 100 samples was tested and evaluated. Positive correlations were found between the soil aggregate stability and the three variables dry unit weight, root length per soil volume, and degree of mycorrhization. Based on robust statistics it turned out that dry unit weight and mycorrhization degree were strongest correlated with soil aggregate stability. Compared to the non-inoculated control plants, mycorrhized White Alder produced significantly more roots and higher soil aggregate stability. Furthermore, the combined biological effect of plant roots and mycorrhizal mycelia on aggregate stability on soil with low density (~15.5 kN/m³) was comparable to the compaction effect of the pure soil from 15.5 to ~19.0 kN/m³. Literature data on the effect of vegetation on the angle of internal friction ?' of the same moraine showed

Linear-dendritic supramolecular complexes as nanoscale reaction vessels for "green" chemistry. Diels-Alder reactions between fullerene C60 and polycyclic aromatic hydrocarbons in aqueous medium.

Science.gov (United States)

Simonyan, Arsen; Gitsov, Ivan

2008-10-21

This study describes the first Diels-Alder (DA) reaction performed in aqueous medium with highly hydrophobic compounds-fullerene (C 60) as the dienophile and anthracene (An) or tetracene (Tet) as the dienes, respectively. The reactions are performed in nanocontainers, constructed by self-assembly of linear-dendritic amphiphilic copolymers with poly(ethylene glycol), PEG or poly(ethylene oxide), PEO as the hydrophilic blocks and poly(benzyl ether) monodendrons as the hydrophobic fragments: G3PEO13k, dG3 and dG2. Comparative studies under identical conditions are carried out with an amphiphilic linear-linear copolymer, poly(styrene)1800- block-PEO2100, PSt-PEO, and the nonionic surfactant Igepal CO-720, IP720. The binding affinity of supermolecules built of these amphiphiles toward the DA reagents decreases in the following order: G3PEO13k > dG3 > PSt-PEO > dG2 > IP720. The kinetic constant of binding is evaluated for tetracene and decreases in a similar fashion: 5 x 10 (-7) M/min (G3PEO13k), through 4 x 10 (-7) M/min (PSt-PEO) down to 1.5 x 10 (-7) M/min for IP720. The mobility of substrates encapsulated in the micellar core, estimated by pyrene fluorescence decay, is 95-121 ns for the micelles of the linear-dendritic copolymers and notably higher for PSt-PEO (152 ns), revealing the much denser interior of the linear analogue. The apparent kinetic constant for the DA reaction of C 60 and Tet within the G3PEO13k supermolecule in aqueous medium is markedly higher than in organic solvent (toluene), 208 vs 1.82 M /min. With G3PEO13k the conversions reach 49% for the DA reaction between C 60 and An, and 55% for C 60 and Tet. Besides the monoadduct (26.5% yield) the reaction with An produces exclusively increasing amounts of D 2 h -symmetric antipodal bis-adduct, whose yield reaches up to 22.5% after 48 h. In addition to the environmentally friendly conditions notable advantages of the synthetic strategy described are the extended stability of the linear

Green Power Partnership 100 Green Power Users

Science.gov (United States)

EPA's Green Power Partnership is a voluntary program designed to reduce the environmental impact of electricity generation by promoting renewable energy. Partners on this list use green power to meet 100 of their U.S. organization-wide electricity use.

Temperature-controlled cross-linking of silver nanoparticles with diels-alder reaction and its application on antibacterial property

Science.gov (United States)

Liu, Lian; Yang, Pengfei; Li, Junying; Zhang, Zhiliang; Yu, Xi; Lu, Ling

2017-05-01

Sliver nanoparticles (AgNPs) were synthesized and functionalized with furan group on their surface, followed by the reverse Diels-Alder (DA) reaction with bismaleimide to vary the particle size, so as to give different antibacterial activities. These nanoparticles were characterized using Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), Ultraviolet-Visible (UV-vis), Nanoparticle Size Analyzer and X-Ray Photoelectron Spectroscopy (XPS). It was found that the cross-linking reaction with bismaleimide had a great effect on the size of AgNPs. The size of the AgNPs could be controlled by the temperature of DA/r-DA equilibrium. The antibacterial activity was assessed using the inhibition zone diameter by introducing the particles into a media containing Escherichia coli, Listeria monocytogenes, and Staphylococcus aureus, respectively. It was found that these particles were effective bactericides. Furthermore, the antibacterial activity of the nanoparticles decreased orderly as the particle size enlarged.

Green Roofs: Standardization and Quality Control of Processes in Green Construction

Directory of Open Access Journals (Sweden)

Korol Elena

2017-01-01

Full Text Available The article considers the problems of standardization and quality control of processes in the construction, improvement of integrated safety of buildings and the implementation of innovative green building technologies, the use of national standards as well as international rating systems for green buildings evaluation. This is one of the priority directions in development of the modern construction. The aim of this study is the analysis of the green roof systems and international standards, which were carried out in the green building industry. The authors have studied traditional and innovative solutions of rational using natural resources and energy, the green roof system with integration of supported solar and wind energy collecting and converting devices and of irrigation system. Some studies provide evidence for the benefits of the modular green roof system in urban green space with microclimate differences. This article presents a new research which advances our knowledge of the economic and environmental services provided by the green roof system. Research reported here also considers the analysis of the Russian and international legislation of the quality control of processes in green construction.

The synergy in green persuasion: Green celebrity endorsers in green advertising: A study of brand-endorser congruence effects in green advertising

OpenAIRE

Blasche, J.; Ketelaar, P.E.

2015-01-01

This study examines celebrity endorser-brand congruence effects in green advertising on the ads' effectiveness. In an experimental survey, Dutch participants (197) saw ads with a congruent or incongruent celebrity endorser. Extending the match-up hypothesis to a novel match-up factor, greenness, the results show that pro-environmental celebrity endorsers yield more favourable attitudes towards the ad, the brand, and purchase intentions compared to non-green celebrity endorsers. Practitioners ...

Green lights

DEFF Research Database (Denmark)

Fisker, Peter Kielberg

This study investigates the effect of drought on economic activity globally using remote sensing data. In particular, predicted variation in greenness is correlated with changes in the density of artificial light observed at night on a grid of 0.25 degree latitude-longitude pixels. I define drought...... as greenness estimated by lagged variation in monthly rainfall and temperature. This definition of drought performs well in identifying self-reported drought events since 2000 compared with measures of drought that do not take greenness into account, and the subsequent analysis indicates that predicted...... variation in greenness is positively associated with year-on-year changes in luminosity: If a unit of observation experiences a predicted variation in greenness that lies 1 standard deviation below the global mean, on average 1.5 - 2.5 light pixels out of 900 are extinguished that year. Finally, an attempt...

Green Chemistry Metrics with Special Reference to Green Analytical Chemistry

Directory of Open Access Journals (Sweden)

Marek Tobiszewski

2015-06-01

Full Text Available The concept of green chemistry is widely recognized in chemical laboratories. To properly measure an environmental impact of chemical processes, dedicated assessment tools are required. This paper summarizes the current state of knowledge in the field of development of green chemistry and green analytical chemistry metrics. The diverse methods used for evaluation of the greenness of organic synthesis, such as eco-footprint, E-Factor, EATOS, and Eco-Scale are described. Both the well-established and recently developed green analytical chemistry metrics, including NEMI labeling and analytical Eco-scale, are presented. Additionally, this paper focuses on the possibility of the use of multivariate statistics in evaluation of environmental impact of analytical procedures. All the above metrics are compared and discussed in terms of their advantages and disadvantages. The current needs and future perspectives in green chemistry metrics are also discussed.

Green Chemistry Metrics with Special Reference to Green Analytical Chemistry.

Science.gov (United States)

Tobiszewski, Marek; Marć, Mariusz; Gałuszka, Agnieszka; Namieśnik, Jacek

2015-06-12

The concept of green chemistry is widely recognized in chemical laboratories. To properly measure an environmental impact of chemical processes, dedicated assessment tools are required. This paper summarizes the current state of knowledge in the field of development of green chemistry and green analytical chemistry metrics. The diverse methods used for evaluation of the greenness of organic synthesis, such as eco-footprint, E-Factor, EATOS, and Eco-Scale are described. Both the well-established and recently developed green analytical chemistry metrics, including NEMI labeling and analytical Eco-scale, are presented. Additionally, this paper focuses on the possibility of the use of multivariate statistics in evaluation of environmental impact of analytical procedures. All the above metrics are compared and discussed in terms of their advantages and disadvantages. The current needs and future perspectives in green chemistry metrics are also discussed.

Green Chemistry Metrics with Special Reference to Green Analytical Chemistry

OpenAIRE

Marek Tobiszewski; Mariusz Marć; Agnieszka Gałuszka; Jacek Namieśnik

2015-01-01

The concept of green chemistry is widely recognized in chemical laboratories. To properly measure an environmental impact of chemical processes, dedicated assessment tools are required. This paper summarizes the current state of knowledge in the field of development of green chemistry and green analytical chemistry metrics. The diverse methods used for evaluation of the greenness of organic synthesis, such as eco-footprint, E-Factor, EATOS, and Eco-Scale are described. Both the well-establis...

Insights into the Diels-Alder Reaction between 3-Vinylindoles and Methyleneindolinone without and with the Assistance of Hydrogen-Bonding Catalyst Bisthiourea: Mechanism, Origin of Stereoselectivity, and Role of Catalyst.

Science.gov (United States)

Yan, Chao-Xian; Yang, Fan; Yang, Xing; Zhou, Da-Gang; Zhou, Pan-Pan

2017-03-17

The Diels-Alder reaction between 3-vinylindoles and methyleneindolinone can proceed both under catalyst-free conditions and with bisthiourea as the catalyst. The reaction with bisthiourea is much faster and results in higher stereoselectivity of the product. The reaction mechanism, origin of stereoselectivity, and role of the catalyst were elaborated based on quantum mechanical calculations and theoretical methods of reactivity indices, NCI, QTAIM, and distortion/interaction models. In the uncatalyzed reaction, the two C-C bonds that are formed undergo conversion from noncovalent to covalent bonding via a concerted asynchronous mechanism. The weak intermolecular interactions formed in the transition state play important roles. The difference between the interaction and distortion energies is responsible for the stereoselectivity. In the catalyzed reaction, bisthiourea induces both the diene and dienophile to approach it via weak intermolecular interactions, which greatly lowers the energy barrier of the reaction and leads to the product with excellent stereoselectivity. The possible pathways of this reaction were explored, which suggested that the formation of the two C-C bonds goes through either a stepwise or concerted asynchronous mechanism. These results detail the reaction mechanism and shed light on both the significant role of the bisthiourea catalyst and the origin of stereoselectivity for this type of Diels-Alder reaction and related ones.

Buying and selling green: deregulation and green power marketing

International Nuclear Information System (INIS)

Evans, Andrew

2000-01-01

This article discusses the increasing trend towards deregulation of electricity markets, and the driving forces for liberalisation in the EU and North America. The use of green tariffs offered by utilities to differentiate themselves from competitors and to gain and keep customers is reported, and the situation with regard to green energy within the deregulated electricity markets in Australia, the EU, Denmark, Finland, Germany, the Netherlands, Portugal, Sweden, the UK, Canada and the USA is outlined. Customers switching as a result of green tariffs, the growing role of renewables, and opportunities for the promotion of green tariffs are discussed. (UK)

Gold-catalyzed tandem hydroamination/formal aza-Diels-Alder reaction of homopropargyl amino esters: a combined computational and experimental mechanistic study.

Science.gov (United States)

Miró, Javier; Sánchez-Roselló, María; González, Javier; del Pozo, Carlos; Fustero, Santos

2015-03-27

A tandem gold-catalyzed hydroamination/formal aza-Diels-Alder reaction is described. This process, which employs quaternary homopropargyl amino ester substrates, leads to the formation of an intrincate tetracyclic framework and involves the generation of four bonds and five stereocenters in a highly diastereoselective manner. Theoretical calculations have allowed us to propose a suitable mechanistic rationalization for the tandem protocol. Additionally, by studying the influence of the ligands on the rate of the gold-catalyzed reactions, it was possible to establish optimum conditions in which to perform the process with a variety of substituents on the amino ester substrates. Notably, the asymmetric version of the tandem reaction was also evaluated. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Analytical Methods for Malachite Green : Completion Report : Malachite Green Analysis in Water.

Energy Technology Data Exchange (ETDEWEB)

Allen, John L.; Gofus, Jane E.; Meinertz, Jeffery R.

1991-06-01

Malachite green is a known teratogen and therefore its use is limited to nonfood fish under an Investigational New Animal Drug permit (INAD), number 2573. Although a charcoal adsorption column was developed to remove malachite green from hatchery water, INAD compliance requires that the malachite green residue concentrations in any effluent from hatcheries using the chemical be quantified. Therefore, we developed a method for the analysis of malachite green residues in water. Enrichment of the residues of malachite green in water on a diol column followed by High Performance Liquid Chromatographic (HPLC) analysis gives a minimum sensitivity of less than 10 ppb for the chemical. When combined with post-column oxidation using a lead oxide post-column reactor, the procedure can be used for the simultaneous analysis of malachite green in its leuco form, a decomposition product of the dye, as well as its chromatic form. Recovery of the leuco form is pH dependent and water samples should be adjusted to pH 6 to optimize recovery of this form. Water samples spiked with malachite green were concentrated on a diol column followed by elution with 0.05 M p-toluene sulfonic acid in methanol. The methanol elutes were analyzed by HPLC. Pond water samples spiked with malachite green and leuco malachite green yielded average recoveries of 95.4% for malachite green and 57.3% for leuco malachite green. Tap water samples spiked with the carbinol form of malachite green gave average recoveries of 98.6%. The method is very sensitive and is capable of detecting malachite green residues in water at less than 10 ppb. Fish culturists, who cannot find an effective replacement for malachite green, can utilize the method to ensure that their effluents comply with INAD regulations. 13 refs., 2 figs., 7 tabs.

THE MEDIATION EFFECTS OF GREEN PERCEIVED CONSUMER SKEPTICISM AND GREEN PERCEIVED RISK IN THE RELATIONSHIP BETWEEN GREENWASHING AND GREEN TRUST

OpenAIRE

LEBLEBİCİ KOÇER, Leyla; DELİCE, Tuğba

2017-01-01

This study was carried out on the consumers in Kayseri and explores the influenceof greenwashing on green trust and discusses the mediation roles of green perceivedskepticism and green perceived risk. 430 consumers were participate in the research.Structural equation modelling was applied to test the research hypothesis. Thisstudy found that greenwashing has a negative association with green trust. In addition,it found that greenwashing is positively associated with green perceived consumersk...

Linking Forests and Fish: The Relationship Between Productivities of Salmonids and Forest Stands in Northern California

Science.gov (United States)

Wilzbach, P.; Frazey, S.

2005-05-01

Productivities of resident salmonid populations, upland, and riparian areas in 25 small watersheds of coastal northern California were estimated and compared to determine if: 1) upland site productivity predicted riparian site productivity; 2) either upland or riparian site productivity predicted salmonid productivity; and 3) other parameters explained more of the variance in salmonid productivity than upland or riparian site productivity. Salmonid productivity was indexed by total salmonid biomass, length of age 1 fish, and percent habitat saturation. Upland and riparian site productivities were estimated using site indices for redwood (Sequoia sempervirens) and red alder (Alnus rubra), respectively. Upland and riparian site indices were correlated, but neither factor contributed to the best approximating models of salmonid biomass or fish length at age one. Salmonid biomass was best described by a positive relationship with drainage area, and length at age was best described by a positive relationship with percent of riparian hardwoods. Percent habitat saturation was not well described by any of the models constructed. Lack of a relationship between upland conifer and salmonid productivity suggests that management of land for timber productivity and component streams for salmonid production in these sites will require separate, albeit integrated, strategies.

The skin prick test – European standards

Directory of Open Access Journals (Sweden)

Heinzerling Lucie

2013-02-01

Full Text Available Abstract Skin prick testing is an essential test procedure to confirm sensitization in IgE-mediated allergic disease in subjects with rhinoconjunctivitis, asthma, urticaria, anapylaxis, atopic eczema and food and drug allergy. This manuscript reviews the available evidence including Medline and Embase searches, abstracts of international allergy meetings and position papers from the world allergy literature. The recommended method of prick testing includes the appropriate use of specific allergen extracts, positive and negative controls, interpretation of the tests after 15 – 20 minutes of application, with a positive result defined as a wheal ≥3 mm diameter. A standard prick test panel for Europe for inhalants is proposed and includes hazel (Corylus avellana, alder (Alnus incana, birch (Betula alba, plane (Platanus vulgaris, cypress (Cupressus sempervirens, grass mix (Poa pratensis, Dactilis glomerata, Lolium perenne, Phleum pratense, Festuca pratensis, Helictotrichon pretense, Olive (Olea europaea, mugwort (Artemisia vulgaris, ragweed (Ambrosia artemisiifolia, Alternaria alternata (tenuis, Cladosporium herbarum, Aspergillus fumigatus, Parietaria, cat, dog, Dermatophagoides pteronyssinus, Dermatophagoides farinae, and cockroach (Blatella germanica. Standardization of the skin test procedures and standard panels for different geographic locations are encouraged worldwide to permit better comparisons for diagnostic, clinical and research purposes.

Structure and Composition of Old-Growth and Unmanaged Second-Growth Riparian Forests at Redwood National Park, USA

Directory of Open Access Journals (Sweden)

Christopher R. Keyes

2014-02-01

Full Text Available Restoration of second-growth riparian stands has become an important issue for managers of redwood (Sequoia sempervirens [D. Don] Endl. forest reserves. Identifying differences between old-growth and second-growth forest vegetation is a necessary step in evaluating restoration needs and targets. The objective of this study was to characterize and contrast vegetation structure and composition in old-growth and unmanaged second-growth riparian forests in adjacent, geomorphologically similar watersheds at Redwood National Park. In the old-growth, redwood was the dominant overstory species in terms of stem density, basal area, and importance values. Second-growth was dominated by red alder (Alnus rubra Bong., Douglas-fir (Pseudotsuga menziesii [Mirbel] Franco, and redwood. Understory species were similar in both forests, with several key differences: Oxalis oregana Nutt. and Trillium ovatum Pursh had greater importance values in the old-growth, and Vaccinium parvifolium Sm., Dryopteris spp. and sedges Carex spp. had greater importance values in the second-growth. Notable differences in structure and composition suggest that restoration practices such as thinning could expedite the acquisition of old-growth characteristics in second-growth riparian forests.

Green Chemistry

Energy Technology Data Exchange (ETDEWEB)

Collison, Melanie

2011-05-15

Green chemistry is the science of chemistry used in a way that will not use or create hazardous substances. Dr. Rui Resendes is working in this field at GreenCentre Canada, an offshoot of PARTEQ Innovations in Kingston, Ontario. GreenCentre's preliminary findings suggest their licensed product {sup S}witchable Solutions{sup ,} featuring 3 classes of solvents and a surfactant, may be useful in bitumen oil sands extraction.

Green Vehicle Guide

Science.gov (United States)

... label Buy green. Save green. Learn about MPG math Discover fuel-saving tips Promote green ... U.S. consumers who have already purchased new vehicles under the fuel economy & greenhouse gas standard! More about the standards » Check ...

Prediction of the chemo- and regioselectivity of Diels-Alder reactions of o-benzoquinone derivatives with thiophenes by means of DFT-based reactivity indices

Science.gov (United States)

Ghomri, Amina; Mekelleche, Sidi Mohamed

2014-03-01

Global and local reactivity indices derived from density functional theory were used to elucidate the regio- and chemoselectivity of Diels-Alder reactions of masked o-benzoquinones with thiophenes acting as dienophiles. The polarity of the studied reactions is evaluated in terms of the difference of electrophilicity powers between the diene and dienophile partners. Preferential cyclisation modes of these cycloadditions are predicted using Domingo's polar model based on the local electrophilicity index, ωk, of the electrophile and the local nucleophilicity index, Nuk, of the nucleophile. The theoretical calculations, carried out at the B3LYP/6-311G(d,p) level of theory, are in good agreement with experimental findings.

On the Reaction of 1,3-Diphenylisobenzofuran and (2-Iodoethynyl(phenyliodonium Triflate. A Unique Case of Oxygen Transfer from the Diels-Alder Adduct to the Diene

Directory of Open Access Journals (Sweden)

Mercè Font-Bardia

2012-07-01

Full Text Available Reaction of 1,3-diphenylisobenzofuran (DPIBF with 2-(iodoethynyl(phenyl-iodonium triflate at room temperature gave the expected Diels-Alder adduct, but using an excess of DFIBF (2 equiv. and performing the reaction at 55 °C or heating at this temperature during the concentration stage, the initial orange solution or product mixture became dark brown and the products 1,2-phenylene-1,2-bis(phenylmethanone and 2-(3-iodo-1,4-diphenylnaphthyl(phenyliodonium triflate were obtained, which suggests an oxygen transfer between DPIBF and the initial adduct.

Direct and Indirect Determinations of Elementary Rate Constants H + O2: Chain Branching; the Dehydration of tertiary-Butanol; the Retro Diels-Alder Reaction of Cyclohexene; the Dehydration of Isopropanol

Science.gov (United States)

Heyne, Joshua S.

Due to growing environmental concern over the continued use of fossil fuels, methods to limit emissions and partially replace fossil fuel use with renewable biofuels are of considerable interest. Developing chemical kinetic models for the chemistry that affects combustion properties is important to understanding how new fuels affect combustion energy conversion processes in transportation devices. This thesis reports the experimental study of several important reactions (the H + O2 branching reaction, the key decomposition reactions of tertiary-butanol, the dehydration reaction of isopropanol, and the retro Diels-Alder reaction of cyclohexene) and develops robust analysis methods to estimate the absolute uncertainties of specific elementary rate constants derived from the experimental data. In the study of the above reactions, both a direct and indirect rate constant determination technique with associated uncertainty estimation methodologies are developed. In the study of the decomposition reactions, a direct determination technique is applied to experimental data gathered in preparation of this thesis. In the case of the dehydration reaction of tertiary-butanol and the retro Diels-Alder reaction of cyclohexene, both of which are used as internal standards for relative rate studies (Herzler et al. 1997) and chemical thermometry (Rosado-Reyes et al. 2013) , analysis showed an ˜20 K difference in the reaction rate between the reported results and the previous recommendations. In light of these discrepancies, an uncertainty estimation of previous recommendations illuminated an uncertainty of at least 20 K for the dehydration reaction of tertiary-butanol and the retro Diels-Alder reaction of cyclohexene, thus resolving the discrepancies. The determination of the H + O2 branching reaction and decomposition reactions of isopropanol used an indirect determination technique. The uncertainty of the H + O2 branching reaction rate is shown to be underestimated by previous

The green agenda

CERN Document Server

Calder, Alan

2009-01-01

This business guide to Green IT was written to introduce, to a business audience, the opposing groups and the key climate change concepts, to provide an overview of a Green IT strategy and to set out a straightforward, bottom line-orientated Green IT action plan.

Sustainable house construction and green financing. Explanation for 'green mortgages'

International Nuclear Information System (INIS)

1997-05-01

The Dutch government finances the sustainable construction of new houses by means of so-called 'green loans'. Extra costs for the construction of a sustainable house are compensated by a lower interest rate for a green loan. In this brochure it is explained when green financing of house construction is possible and how to apply for such loans

Synthesis and characterization of a novel double cross-linked hydrogel based on Diels-Alder click reaction and coordination bonding.

Science.gov (United States)

Li, Shubin; Wang, Lu; Yu, Xuemei; Wang, Chengli; Wang, Zhenyu

2018-01-01

Hydrogels, promising biological materials, need to have both strong mechanical properties and also inherent self-healing properties. In this work a double cross-linked network (DN) hydrogel was designed and prepared by combining a Diels-Alder click reaction and coordination effects. This DN hydrogel had good thermodynamic properties, anti-EDTA performance and self-healing properties. In addition, the mechanical properties, swelling properties and surface morphology of DN hydrogels can be controlled by adjusting the ratio of Fe 3+ -catechol. The adjustment of pH value can change the color, crosslinking mode and mechanical properties of the DN hydrogel. This smart hydrogel created from DA click chemistry and coordination effects has significance for guiding the design of new hydrogels with good mechanical properties, self-healing properties and controlled cross-link density. Copyright © 2017. Published by Elsevier B.V.

Green roofs

CSIR Research Space (South Africa)

Van Wyk, Llewellyn V

2010-04-01

Full Text Available , beetles and spiders); and the number of birds that nest in vegetated roofs (including kestrels, swallows, and wagtails). Objective The primary objective of a green roof is to create a living habitat in an otherwise barren environment, hence the use... the negative environmental impacts including plant and insect specie loss. Thus at a philosophical level green roofs support the notion “replace what you displace”. Key ecological issues that can be addressed through green roofs include: Negative effects...

Green energy in Europe: selling green energy with green certificates

International Nuclear Information System (INIS)

Ouillet, L.

2002-01-01

Sales of green power products are booming in Europe: 50,000 customers in the United Kingdom, 775,000 in the Netherlands and 300,000 in Germany. Laws of physics are however formal: the way in which electricity flows within the grid does not allow suppliers to assure customers that they are directly receiving electricity produced exclusively from renewable energy sources. What are marketers selling their customers then? Laetitia Ouillet, Greenprices, takes a closer look and focuses on the potential of selling green energy in the forms of renewable energy certificates. (Author)

Green Roofs: A Part of Green Infrastructure Strategy for Urban Areas

Science.gov (United States)

This is a presentation on the basics of green roof technology. The presentation highlights some of the recent ORD research projects on green roofs and provides insight for the end user as to the benefits for green roof technology. It provides links to currently available EPA rep...

Green electricity buyer's guide

International Nuclear Information System (INIS)

Kelly, B.; Klein, S.; Olivastri, B.

2002-06-01

The electricity produced in whole or in large part from renewable energy sources like wind, small hydro electricity and solar energy, is generally referred to as green electricity. The authors designed this buyer's guide to assist customers in their understanding of green electricity, as the customers can now choose their electricity supplier. The considerations and steps involved in the purchasse of green electricity are identified, and advice is provided on ways to maximize the benefits from the purchase of green electricity. In Alberta and Ontario, customers have access to a competitive electricity market. The emphasis when developing this guide was placed firmly on the large buyers, as they can have enormous positive influence on the new market for green electricity. The first chapter of the document provides general information on green electricity. In chapter two, the authors explore the opportunity for environmental leadership. Chapter three reviews the basics of green electricity, which provides the link to chapter four dealing with the creation of a policy. Purchasing green electricity is dealt with in Chapter five, and maximizing the benefits of green electricity are examined in Chapter Six. 24 refs., 3 tabs

The synergy in green persuasion: Green celebrity endorsers in green advertising: A study of brand-endorser congruence effects in green advertising

NARCIS (Netherlands)

Blasche, J.; Ketelaar, P.E.

2015-01-01

This study examines celebrity endorser-brand congruence effects in green advertising on the ads' effectiveness. In an experimental survey, Dutch participants (197) saw ads with a congruent or incongruent celebrity endorser. Extending the match-up hypothesis to a novel match-up factor, greenness, the

Reduction of malachite green to leucomalachite green by intestinal bacteria.

OpenAIRE

Henderson, A L; Schmitt, T C; Heinze, T M; Cerniglia, C E

1997-01-01

Intestinal microfloras from human, rat, mouse, and monkey fecal samples and 14 pure cultures of anaerobic bacteria representative of those found in the human gastrointestinal tract metabolized the triphenylmethane dye malachite green to leucomalachite green. The reduction of malachite green to the leuco derivative suggests that intestinal microflora could play an important role in the metabolic activation of the triphenylmethane dye to a potential carcinogen.

Mild and modular surface modification of cellulose via hetero Diels-Alder (HDA) cycloaddition.

Science.gov (United States)

Goldmann, Anja S; Tischer, Thomas; Barner, Leonie; Bruns, Michael; Barner-Kowollik, Christopher

2011-04-11

A combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and hetero Diels-Alder (HDA) cycloaddition was used to effect, under mild (T ≈ 20 °C), fast, and modular conditions, the grafting of poly(isobornyl acrylate) (M(n) = 9800 g mol(-1), PDI = 1.19) onto a solid cellulose substrate. The active hydroxyl groups expressed on the cellulose fibers were converted to tosylate leaving groups, which were subsequently substituted by a highly reactive cyclopentadienyl functionality (Cp). By employing the reactive Cp-functionality as a diene, thiocarbonyl thio-capped poly(isobornyl acrylate) synthesized via RAFT polymerization (mediated by benzyl pyridine-2-yldithioformiate (BPDF)) was attached to the surface under ambient conditions by an HDA cycloaddition (reaction time: 15 h). The surface-modified cellulose samples were analyzed in-depth by X-ray photoelectron spectroscopy, scanning electron microscopy, elemental analysis, Fourier transform infrared (FT-IR) spectroscopy as well as Fourier transform infrared microscopy employing a focal plane array detector for imaging purposes. The analytical results provide strong evidence that the reaction of suitable dienophiles with Cp-functional cellulose proceeds under mild reaction conditions (T ≈ 20 °C) in an efficient fashion. In particular, the visualization of individual modified cellulose fibers via high-resolution FT-IR microscopy corroborates the homogeneous distribution of the polymer film on the cellulose fibers.

Biomimetic Aerobic C-H Olefination of Cyclic Enaminones at Room Temperature: Development toward the Synthesis of 1,3,5-Trisubstituted Benzenes.

Science.gov (United States)

Yu, Yi-Yun; Georg, Gunda I

2014-04-14

A green and mild protocol for the dehydrogenative olefination of cyclic enaminones was devised via palladium catalysis at room temperature using oxygen as the terminal oxidant. The synthetic utility of the olefinated cyclic enaminones afforded a series of unique 1,3,5-trisubstituted benzenes via an unanticipated Diels-Alder tandem reaction. The broad substrate scope and good yields achieved with this new protocol provide an alternative pathway for arene functionalization.

Copper(I)-Catalyzed Asymmetric Desymmetrization through Inverse-Electron-Demand aza-Diels-Alder Reaction: Efficient Access to Tetrahydropyridazines Bearing a Unique α-Chiral Silane Moiety.

Science.gov (United States)

Wei, Liang; Zhou, Yu; Song, Zhi-Min; Tao, Hai-Yan; Lin, Zhenyang; Wang, Chun-Jiang

2017-04-11

An unprecedented copper(I)-catalyzed asymmetric desymmetrization of 5-silylcyclopentadienes with in situ formed azoalkene was realized through an inverse-electron-demand aza-Diels-Alder reaction (IEDDA) pathway, in which 5-silylcyclopentadienes served as efficient enophiles. This new protocol provides a facile access to the biologically important heterocyclic tetrahydropyridazines containing a unique α-chiral silane motif and three adjoining stereogenic centers in generally good yield (up to 92 %) with exclusive regioselectivity, high diastereoselectivity (>20:1 diastereomeric ratio), and excellent enantioselectivity (up to 98 % enantiomeric excess). DFT calculations and control experiments further confirmed the proposed reaction mechanism. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Influences of Thermo-Vacuum Treatment on Colors and Chemical Compositions of Alder Birch Wood

Directory of Open Access Journals (Sweden)

Yan Yang

2015-10-01

Full Text Available With high temperature-heat treatment, the dimensional stability and durability of wood is improved and wood color is darkened as well. In this paper, alder birch wood (Betula alnoides was treated by the Thermo-Vacuum Treatment (TVT. The changes of wood color parameters and the chemical composition were determined by the CIE1976 L*a*b* method and the chemical analysis method, respectively. The results were revealed as follows: (1 A lower value of lightness, L*, and a higher value of total color difference, △E*, were obtained at the higher heat-treatment temperatures and longer treatment time. (2 The higher the heat-treatment temperatures and the longer the heat-treatment times were, the lower the contents of hemicellulose and cellulose were and the higher the content of lignin was. Moreover, Fourier Transform infrared spectroscopy (FTIR analysis demonstrated that the characteristic absorption peaks of cellulose, hemicellulose, and lignin diminished. The acetylation reaction of hemicellulose and the degradation reaction of groups of lignin side chain occurred during TVT. (3 TVT degraded the chemical composition of cell walls, which resulted in further changes of the wood color. A significant correlation existed between the differences of color indices and the differences of the chemical composition after TVT.

Greening Steel Work: Varieties of Capitalism and the "Greening" of Skills

Science.gov (United States)

Evans, Claire; Stroud, Dean

2016-01-01

An important driver of change in work, employment and skills is European Union policy aims of sustainable economic growth and the cultivation of a green economy. Part of the latter--which is supported by increasing environmental regulation--focuses on the development of a "green skills agenda," which involves the "greening" of…

In the Green

Science.gov (United States)

Kennedy, Mike

2011-01-01

Education officials used to debate whether they could afford to pursue green design and construction. Now the green movement has gained a foothold not just in education, but in society at large, and the prevailing attitude seems to have shifted. Can schools afford "not" to go green? As budgets are slashed repeatedly, education administrators must…

Determination of ergocalciferol in human plasma after Diels-Alder derivatization by LC–MS/MS and its application to a bioequivalence study

Directory of Open Access Journals (Sweden)

Pritesh Contractor

2017-12-01

Full Text Available An accurate, sensitive and selective method is developed for determination of ergocalciferol (vitamin D2 in human plasma using LC–MS/MS. After liquid-liquid extraction with n-hexane, ergocalciferol was derivatized by reacting with 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD, a strong dienophile based on Diels-Alder reaction. Ergocalciferol and its deuterated internal standard, ergocalciferol-d6, were analyzed on X Select CSH C18 (100 mm×4.6 mm, 2.5 µm column using acetonitrile and 0.1% (v/v formic acid in water containing 0.14% methylamine within 6.0 min under gradient elution mode. Tandem mass spectrometry in positive ionization mode was used to quantify ergocalciferol by multiple reaction monitoring (MRM. Entire data processing was done using Watson LIMS™ software which provided excellent data integrity and high throughput with improved operational efficiency. The major advantage of this method includes higher sensitivity (0.10 ng/mL, superior extraction efficiency (≥83% and small sample volume (100 µL for processing. The method was linear in the concentration range of 0.10–100 ng/mL for ergocalciferol. The intra-batch and inter-batch accuracy and precision (% CV values varied from 97.3% to 109.0% and 1.01% to 5.16%, respectively. The method was successfully applied to support a bioequivalence study of 1.25 mg ergocalciferol capsules in 12 healthy subjects. Keywords: Ergocalciferol, Diels-Alder reaction, 4-phenyl-1,2,4-triazoline-3,5-dione, LC–MS/MS, Human plasma

The green dilemma: Reflections of a Generation Y consumer cohort on green purchase behaviour

Directory of Open Access Journals (Sweden)

A. Muposhi

2015-12-01

Full Text Available Green consumerism has garnered much scholarly interest in recent years. However, research on the influence of the Social Dilemma Theory (SDT on green purchase behaviour has been scarce. Using data generated from sixteen in-depth-interviews, the present study identified perceived efficacy, perceived cost, in-group and self-identity, trust and peer influence as the main antecedents of SDT that influence green purchase behaviour. The findings of the study imply that to promote and institutionalise green purchase behaviour, marketers need to enhance perceived efficacy, trust in green products, reduce perceived cost, align green products with the consumers’ sought image and utilise peer networks when structuring green marketing messages.

Is green economy achievable through championing green growth? A local government experience from Zambia

Directory of Open Access Journals (Sweden)

Phiri Rodgers

2016-03-01

Full Text Available The need to enhance environmental sustainability, sustainable development and growth that takes into account the well-being of the people and nature because of the increased production and consumption of goods and services is the major driver to the introduction of green economy in Zambia and countries in southern Africa. This article examines the extent to which local government in Zambia has embraced green growth and green economy and critically analyses the concept of green economy and green growth. This study is based on a review of planning and policy documents, a household questionnaire survey and interviews with various institutions, planners and rural development organisations. A number of policies implemented at the local government level were analysed and reflected upon irrespective of whether they contain the components of green growth and green economy and the extent to which they contribute to attaining green economy. The article argues that the need for economic diversification is important as far as green economy is concerned. The article recommends the need to invest in research and development in order to find more carbon-free economic activities. The conclusion is that local government is key to achieving green growth and green economy, because it is involved at all levels, from policy formulation to implementation.

Green roof Malta

OpenAIRE

Gatt, Antoine

2015-01-01

In Malta, buildings cover one third of the Island, leaving greenery in the dirt track. Green roofs are one way to bring plants back to urban areas with loads of benefits. Antoine Gatt, who manages the LifeMedGreenRoof project at the University of Malta, tells us more. http://www.um.edu.mt/think/green-roof-malta/