Poly(ethylene terephthalate) (PET) was depolymerized to ethylene glycol and terephthalic acid in high-temperature liquid water at temperature higher than 493 K and the depolymerization of PET was enhanced by the addition of terephthalic acid in the reaction system.   

Surface functionalization of poly(ethylene terephthalate) (PET) film or track-etched membrane was performed using the methods of organic synthesis conducted at the solid-liquid interface. Basic hydrolysis in aqueous acetonitrile followed by permanganate oxidation in diluted sulfuric acid created new...

A series of high molecular weight copolymers based on poly(L-lactic acid) (PLLA) as the biodegradable aliphatic segments, poly(butylene terephthalate) (PBT) as the rigid aromatic segments and hydrophilic poly(ethylene glycol) (PEG) as the soft segments were synthesized with the aim of developing novel polymer materials which could combine high physical properties with good biodegradability. Via direct melt polycondensation of terephthalic acid (TPA), 1,4-butanediol (BDO), poly(L-lactic acid) oligomer (OLLA) and PEG, biodegradable aliphatic/aromatic copoly(ester-ether)s, poly(butylene terephthalate-co-lactate-co-ethylene glycol) (PBTLG), were prepared. The effect of the introduction of PEG soft segments on the synthesis, mechanical properties and thermal stabilities as well as the degradati...

Rare-earth coordination polymers or lanthanide-organic frameworks with hitherto unreported crystal structures have been obtained on the basis of the "light" lanthanides Pr, Nd, Sm, and Eu in combination with terephthalic acid and using a slightly altered literature synthesis procedure. Rietveld refinement has shown that powder XRD patterns of such compounds are largely dominated by the positions of the heavy elements, pointing to isostructural networks for all four terephthalate-based materials. An in-depth luminescence study has been performed on the reported MOFs, showing rare praseodymium and samarium emission in the visible spectrum, aside from the strong europium luminescence and the near-infrared emission from both a terephthalate and 2,5-pyridinedicarboxylate based neodymium-MOF. PMID:23078525

The interest in coordination polymers, also known as metal-organic frameworks, has risen drastically over the past 2 decades. In this time, the field has matured and given rise to a diverse range of crystalline structures possessing various functionalities. Coordination polymers are typically formed from the self assembly of metal ions which serve as nodes and organic ligands which act as bridges. By the careful selection of the organic ligand and the metal ion, the overall physical properties of the material may be tuned. In this work, the use of organometallic bridging ligands are explored using facially metalated aryl carboxylates ligands to synthesize metal-organometallic frameworks (MOMFs). Therefore, with the aim of synthesizing [CpM]+-functionalized (M = FeII, RuII; Cp = cyclopentadienyl) coordination polymers and metal organic frameworks, various [CpFe]+and [CpRu] + functionalized aryl carboxylates were synthesized and characterized. In particular, the [CpFe]+-functionalized benzoic, terephthalic and trimesic acids as well as the [CpRu]+-functionalized terephthalic acid were made. Using the [CpFe]+ complexes of the benzoic and terephthalic acid as bridging ligands, a number of 1D and 2D coordination polymers were synthesized. For instance, the reaction of [CpFe]+-functionalized benzoic acid with CdCl2 yielded the 1D chain of [Cd(benzoate)Cl 2]?H2O whilst the reaction of [CpFe]+-functionalized terephthalic acid with Cu(NO3)2?6H2O yielded a 2D square grid sheet. Using the [CpFe]+-functionalized terephthalic acid, a series of polymorphic, 3D metal-organometallic frameworks of the general formula [M3(terephthalate)4(mu-H2O)2(H 2O)2][NO3]2?xsolvent (M = Co II, NiII ; solvent = EtOH, DMF, H2O) were synthesized and fully characterized. The polymorphic nature of these frameworks may be attributed to the different orientations that the [CpFe]+ moiety may adapt within the cavities in the 3D frameworks. The selectivity of the desolvated forms of the polymorphs for various alcohols was also probed. A framework having the same 3D topology but slightly different composition as the polymorphic frameworks of [M3(terephthalate)4(mu-H 2O)2(H2O)2][NO3]2? xsolvent was obtained using MnBr2?4H2O. The solvothermal reaction of [CpFe]+-functionalized terephthalic acid and Co(NO3)2?6H2O afforded the first microporous metal-organometallic phosphate. This 3D framework formed a cubic, 12-connected face centered net featuring a novel dodecanuclear truncated tetrahedral node consisting of [CpFe(terephthalate)]+, CoII, F- and phosphate ions. Lastly, the [CpFe]+-functionalized terephthalic acid was successfully reticulated into the MIL-88 and MIL 53 framework topologies indicating that the metalated ligand may be used to synthesis both known and novel 3D metal organic frameworks.

The conditions of synthesis of statistical poly(ethylene succinate-co-terephthalate) copolymers (2GTS) and high molecular weight poly(ethylene succinate) (PES) with good hydrolytic and optical parameters, designed for the production of biodegradable products and resins, are presented in this article. Copolymers were prepared by melt polycondensation of bis-(b-hydroxyethylene terephthalate) (BHET) and succinic acid (SA) with excess of ethylene glycol (2G) in the presence of a novel titanium/silicate catalyst (C-94) and catalytic grade of germanium dioxide (GeO2) as cocatalyst. The chemical structure and physical properties of those materials were characterized by 1H NMR, FT-IR, dynamical-mechanical thermal analyses (DMTA), differential scanning calorimetry (DSC), solution viscosity and spec...

Polyethylene terephthalate synthesis by polycondensation of its monomer bis-hydroxy ethylene terephthalate was investigated. Two catalysts were studied; a homogenous one based on antimony and a heterogeneous one based on hydrotalcite. Two methods were applied to monitor the reaction progress; thermo...

Core-shell hydrophilic superparamagnetic iron oxide (SPIO) nanoparticles, surface functionalized with either terephthalic acid or 2-amino terephthalic acid, showed large negative MRI contrast ability, validating the advantage of using low molecular weight and ?-conjugated canopies for engineering functional nanostructures with superior performances. PMID:23066527

A novel class of polyimides, N-phenylated wholly aromatic non-cyclic polyimides, was synthesized by the low-temperature solution and two-phase phase-transfer catalyzed polycondensations of new aromatic bis(imidoyl chloride)s, N,N?-diphenylisophthalimidoyl chloride and N,N?-diphenylterephthalimidoyl chloride, with aromatic dicarboxylic acids, isophthalic acid and terephthalic acid. The resulting polyimides were all white in color and had reduced viscosities of 0.11–0.14 dl g?1. Compared with the conventional polyimides having cyclic imide structures, these N-phenylated non-cyclic polyimides exhibited better solubility in various organic solvents, reduced crystallinity and lower glass transition temperatures and thermal stability. The reduced viscosity of a typical polyimide decreased rapidly upon UV light irradiation, indicating the occurrence of photodegradation. Before the polymer synthesis, the effects of reaction medium, organic and inorganic bases and phase-transfer catalyst were studied on the solution and two-phase reactions of N,N?-diphenylisophthalimidoyl chloride with benzoic acid.   

Benzoic acid is found to undergo carboxylation by warming with carbon tetrachloride in aqueous alkali in the presence of copper powder with ?-cyclodextrin as catalyst. The reaction under mild conditions gives terephthalic acid in good yield with high selectivity.   

In this study, a microemulsion electrokinetic chromatography (MEEKC) method was developed to analyze and detect several aromatic acids (benzoic acid (BA), isophthalic acid (IPA), terephthalic acid (TPA), p-toluic acid (p-TA), 4-carboxylbenzaldehyde (4-CBA), trimesic acid (TSA), trimellitic acid (TMA), o-phthalic acid (OPA), and hemimellitic acid (HMA)), which are common organic impurities produced by liquid-phase catalytic oxidation of p-xylene to TPA. The effects of microemulsion composition, column temperature, column length and applied voltage were examined in order to optimize the aromatic acid separations. This work demonstrated that variation in the concentration of surfactant (sodium dodecyl sulfate (SDS)) and oil phase (octane) had a pronounced effect on separation of the nine aromatic acids. It was also found that a decrease in column length had the greatest effect on shortening separation time and improving separation resolution for these aromatic acids when compared to that of an increase in column temperature or applied voltage. However, the nature and concentration of cosurfactants and organic modifiers were found to play only minor roles in the separation mechanism. Thus, a separation with baseline resolution was achieved within 14 min by using a microemulsion solution of pH 2.0 containing 3.7% SDS, 0.975% octane, and 5.0% cyclohexanol; and a 50-cm capillary column (effective length of 40-cm) at 26 degrees C. As a result, the developed MEEKC method successfully determined eight impurities of aromatic acids in the mother liquors produced from the oxidation synthesis of TPA. PMID:19167001

The rheological properties of binary blends of polystyrene (PS) with biodegradable polyesters were investigated. The biodegradable polyesters were: polylactic acid (PLA), polycaprolactone (PCL), poly(tetramethylenemadipate-co-terephthalate (EBU). All blends displayed non-Newtonian behavior, and ze...

Telechelic poly(butylene terephthalate) (PBT) ionomers have been prepared by melt synthesis using a new polycondensation process that involves a pre-reaction of sulfobenzoic acid sodium salt with butanediol. No side reaction occurs and the incorporation of the ionic groups is quantitative. The addition of a buffer agent, such as Na3PO4, to the catalyst reduces the THF formation and improves the polycondensation rate. The comparison of the thermo-mechanical and physical properties between random and telechelic ionomers is also reported. The ionic groups act as chain-extension reversible electrostatic links for telechelic ionomers while act as cross-links in random ionomers. Therefore, random ionomers present a consistently higher melt viscosity compared to telechelic ionomers and to PBT and...

A novel series of 1,4-bis(6-(substituted phenyl)-[1,2,4]-triazolo[3,4-b]-1,3,4-thiadiazoles (5a-b) and 4-bis(substituted phenyl)-4-thiazolidinone derivatives (7a-c) have been synthesized from terephthalic dihydrazide (1) through multistep reaction sequence. 1,4-Bis(5-aryl-1,3,4-oxadiazole-2yl) benzene derivatives (2a-f) and bis-substituted terephthalohydrazide (6a-e) were also synthesized from terephthalic dihydrazide by cyclization with various aromatic acids and aldehydes. Terephthalic dihydrazide (1) was obtained from poly(ethylene terephthalate) waste from reaction with hydrazine hydrate in good yield (86%). All the synthesized compounds were screened for their antibacterial activities against various bacteria and fungi strains. Several of these compounds showed potential antibacterial...

Acoustic cavitation plays an important role in sonochemical processes and the rate of sonochemical reaction is influenced by sonication parameters. There are several methods to evaluate cavitation activity such as chemical dosimetry. In this study, to comparison between iodide dosimetry and terephthalic acid dosimetry, efficacy of sonication parameters in reactive radical production has been considered by iodide and terephthalic acid dosimetries. For this purpose, efficacy of different exposure parameters on cavitations production by 1MHz ultrasound has been studied. The absorbance of KI dosimeter was measured by spectrophotometer and the fluorescence of terephthalic acid dosimeter was measured using spectrofluorometer after sonication. The result of experiments related to sonication time and intensity showed that with increasing time of sonication or intensity, the absorbance is increased. It has been shown that the absorbance for continuous mode is remarkably higher than for pulsing mode (p-valueacoustic cavitation activity in ultrasound field. PMID:22766173

The direct introduction of a carboxylic group into an aromatic carboxylic acid has been considered difficult theoretically. Recently, the regioselective syntheses of terephthalic acid, 4,4prime-biphenyldicarboxylic acid and 2,6-naphthalene-dicarboxylic acid have been achieved by the carboxylation of benzoic acid, 4-biphenylcarboxylic acid and 2-naphthalenecarboxylic acid, respectively, with carbon tetrachloride and copper powder in aqueous alkali, using b-cyclodextrin (b-CyD) as mediator under mild conditions. The one-pot syntheses of terephthalic acid, 4,4prime-biphenyldicarboxylic acid and 2,6-naphthalene-dicarboxylic acid have been attained by the carboxylation of benzene, biphenyl and naphthalene, respectively, with carbon tetrachloride and copper powder in aqueous alkali, using b-CyD ...

Abstract From a screening on agar plates with bis(benzoyloxyethyl) terephthalate (3PET), a Bacillus subtilis p-nitrobenzylesterase (BsEstB) was isolated and demonstrated to hydrolyze polyethyleneterephthalate (PET). PET-hydrolase active strains produced clearing zones and led to the release of the 3PET hydrolysis products terephthalic acid (TA), benzoic acid (BA), 2-hydroxyethyl benzoate (HEB), and mono-(2-hydroxyethyl) terephthalate (MHET) in 3PET supplemented liquid cultures. The 3PET-hydrolase was isolated from non-denaturating polyacrylamide gels using fluorescein diacetate (FDA) and identified as BsEstB by LC-MS/MS analysis. BsEstB was expressed in Escherichia coli with C-terminally fused StrepTag II for purification. The tagged enzyme had a molecular mass of 55.2 kDa and a specific a...

Thermochemolysis–gas chromatography in the presence of tetramethylammonium acetate was applied to the direct determination of terephthalic acid (TPA) contained in solid decomposition products obtained from the hydrothermal recycling process of poly(ethylene terephthalate) (PET). On the chromatograms of the hydrothermal decomposition products of PET, a sharp peak of the TPA component was clearly observed as its corresponding dimethyl ester formed through the thermochemolysis reaction. Based on the peak intensities, the contents of TPA in the decomposition products were determined precisely and rapidly without using any cumbersome sample pretreatments.   

The biotolerant and haemodynamic effects of three types of woven polyethylene terephthalate (Dacron) arterial prostheses were compared. Two of these were unmodified, one low, one high porosity; and the third was the latter type radiation graft copolymerized with 5% acrylic acid. The prostheses were ...

Chemical modification of pore internal surfaces with 0.31 and 0.54 ?m in diameter in poly(ethylene terephthalate) (PET) was examined using the alkylation reaction of the carboxylic acids on the surfaces. The chemical incorporation of the reagent on the surfaces was confirmed by the fluorescence microscope images of the membranes reacting with the alkylation reagent bearing a pyrene fluorophore.   

Totally biodegradable, double-layered antimicrobial composite Sheets were introduced for food packaging. The substrate layers of the sheets were prepared from poly (lactic acid) (PLA) and sugar beet pulp (SBP) or poly (butylene adipate-co-terephthalate (PBAT) and SBP by a twin-screw extruder. The ac...

Polyesters containing aromatic moiety in the main chain have been synthesized by enzymatic polymerization of dicarboxylic acid divinyl esters and glycols under mild reaction conditions. Divinyl esters of isophthalic acid, terephthalic acid, and p-phenylene diacetic acid, were used as new monomer for the enzymatic polymerization. Effects of the polymerization conditions were systematically investigated in the polymerization of divinyl isophthalate and 1,6-hexanediol. Candida antarctica lipase afforded the polymer of the highest molecular weight. Methylene chain length of the glycol affected the polymer yield and molecular weight. Divinyl terephthalate was enzymatically polymerized under the similar reaction conditions, yielding the polymer of lower molecular weight. Enzymatic polymerization of divinyl sebacate and p-xylylene glycol also afforded the aromatic polyester.   

Crystal structure of potassium hydrogen terephthalate was determined by X-ray diffraction. Crystals have monoclinic unit cells with C2/c,?a = 18.776(6), b = 3.761(3), c = 11.150(4) Å, ? = 94.72(3)°, V = 784.6(6) Å3, and Z = 4. Acid anions form a one-dimensional chain linked by short (RO···O = 2.459(3) Å) and symmetric hydrogen bonds. The acidic hydrogen was distributed at two equivalent sites in the hydrogen bond.   

X-ray photoelectron spectroscopy-XPS allows the determination of all elements of the periodical table, except hydrogen and helium, and is a very used technique for the polymers characterization, its spectra constitutes a 'fingerprint' of the material. Two samples of polymers were prepared from glycerol and fumaric acid and glycerol and terephthalic acid, with a molar ratio of 1:1 and 1:1.5. The general spectra show the presence of carbon and oxygen, the main components of the polymer. From the binding energies values of the C1s and O1s high resolution spectra it was possible to determine the carbon functional groups. Their concentration were determined and the presence of the aromatic carbon in the terephthalic polyesters was observed, and also similar proportions of aliphatic carbon and ester groups in the fumaric acid polyesters. For both polyesters, an amount of carboxyl group appears, indicating the terminal non-reacted groups. These results were confirmed qualitatively by FTIR. (author)

In this study, the synthesis of bis-(2-ethylhexyl) terephthalate, via the transesterification reaction of dimethyl terephthalate (DMT) by 2-ethylhexanol in the presence of different heterogeneous catalysts, such as Pb(OAc)23H2O, Cd(OAc)22H2O, Zn(OAc)22H2O, Hg(OAc)2, Ca(OAc)2H2O, Cu(OAc)2H2O, NaOAc, CaCO3, CaO, ZnSO47H2O, and sulfated zirconia, has been investigated. The reactivity of the catalysts in the reaction progress has been studied and compared. It was found that, hydrated cadmium acetate and sulfated zirconia were reactive catalysts to this reaction. The extent of transesterification of methyl ester groups reached up to 93% and 85.6% using these catalysts, respectively.

A detailed chromatographic investigation has been carried out on the influence of triphenyl phosphite addition in molten poly(ethylene terephthalate) or poly(ethylene terephthalate)/poly(butylene terephthalate) blends. The observed molecular weight evolution corresponds to torque and viscosity obser...

Several properties of fibres and monofilaments made from polymers such as polyamide 6 (PA), poly(ethylene terephthalate) (PET), polypropylene (PP), aliphatic polyester of butanediol, succinic and adipic acids (PBSA), aliphatic-aromatic polyester of butanediol, terephthalic and adipic acids (PBTA) have been studied. Wettability of monofilaments has been tested by dynamic contact angle method, so surface free energy of synthetic fibres could be calculated. A tensiometer was used for testing the fibre-to-fibre friction coefficient, Young's modulus and bending modulus. It was found that the surface properties of fibres from synthetic polymers such as surface free energy, moisture absorption, and friction coefficient are related to the physical as well as physical-chemical properties, elasticit...

Abstract A series of poly(ethylene terephthalate-co-4,4--bibenzoate)s (PETBBs) were prepared via direct esterification from the monomers of terephthalic acid (TPA), 4,4--biphenyl dicarboxylic acid (BPDA), and ethylene glycol (EG) with different molar ratios. The chemical compositions of the obtained PETBBs, investigated by H1-NMR, were identical with the feed ratio, and the high molecular weights of PETBBs were confirmed by GPC analysis. The glass transition, crystallization, and melting behavior of them were measured by DSC; the results indicated that, in the range of 5-25 mol% of BPDA addition, the glass transition temperature (Tg) increased almost linearly and the melting temperature (Tm) decreased with increasing content of BPDA unit. As expected, the crystallization of PETBB became di...

Biodegradable aliphatic/aromatic copolyesters, poly(butylene terephthalate-co-lactate) (PBTL) were prepared via direct melt polycondensation of terephthalic acid (TPA), 1,4-butanediol (BDO) and poly(L-lactic acid) oligomer (OLLA). The effects of polymerization time and temperature, as well as aliphatic/aromatic moiety ratio on the physical and thermal properties were investigated. The largest molecular weight of the copolyesters was up to 64100 with molecular weight distribution index of 2.09 when the polycondensation was carried out at 230?C for 6 h. DSC, XRD, DMA and TGA analysis clearly indicated that the degree of crystallinity, glass-transition temperature, melting point, decomposition temperature, tensile strength, elongation and Young?s modulus were influenced by the ratio between T...

Two MOFs were reported based on Zn(II) with 1,2-bis(4-pyridyl)hydrazine (L1); a two-dimensional interpenetrating MOF I of formula [Zn2(L1)2(L2)2]? was formed with terephthalic acid (L2) as an additional linker. A three-dimensional MOF II of formula [Zn2(L1)2(L3)2]?, was formed with the use of a larg...

This patent describes a process for separating a component from an O{sub 2}/N or CO{sub 2}/CH{sub 4} gas mixture containing. It comprises: contracting the gas mixture with one side of a gas separation membrane comprising a thin layer predominantly of a polyester or copolyester derived form the reaction of an aromatic dicarboxylic acid or derivative thereof and greater than 50 mol percent of a tetrabromobisphenol, or divalent cyclododecyl and wherein the aromatic discarboxylic acid or divalent cyclododecyl and wherein the aromatic dicarboxylic acid or derivative thereof comprises 80 mole percent or more of isophthalic acid or its dichloride and/or 4-bromoisophthalic acid or its dichloride and 20 mole percent or less of terephthalic acid or its dichlorid and/or 2-bromoterephthalic acid or its dichloride as the dicarboxylic acid compound, or 30 mole percent or less of isophthaloyl dichloride and/or 4-homoisophthalic acid or its dichloride and 70 mole percent or more of terephthalic acid or its dichloride and/or 2-bromoterepohthalic acid or is dichloride; the membrane having a combination of high selectivity and high permeation rate values, while maintaining a pressure differential across the two sides of the membrane and removing the permeated component from the other side of the membrane.

The effect of various primary and secondary bile acids on the rates of synthesis of all major bile acids was studied in the live rat with an extracorporal bile duct. Bile acid synthesis was determined using HPLC based on mass or by isotope dilution. Derepressed rates of bile acid synthesis (30-54 h)...

Abstract in english Antimony is a common catalyst in the synthesis of polyethylene terephthalate used for food-grade bottles manufacturing. However, antimony residues in final products are transferred to juices, soft drinks or water. The literature reports mentions of toxicity associated to antimony. In this work, a green, fast and direct method to quantify antimony, sulfur, iron and copper, in PET bottles by X-ray fluorescence spectrometry is presented. 2.4 to 11 mg Sb kg-1 were found in 20 (more) samples analyzed. The coupling of the multielemental technique to chemometric treatment provided also the possibility to classify PET samples between bottle-grade PET/recycled PET blends by Fe content.

Complexes [Ca(H2O)2(Dmf@CB[6])(Bdc)] ? DMF ? 4H2O (I) and [Ca(H2O)3(Dmf@CB[6])]Cl2 ? 2H2O (II) are synthesized by the heating (95?C) of a mixture of calcium chloride and cucurbit[6]uril (CB[6]) in a mixture of dimethylformamide (DMF) and water with the addition of terephthalic acid (H2Bdc) in the case of complex I or triethylamine for complex II. The compounds are characterized by X-ray diffraction analysis, IR spectroscopy, and thermogravimetric and elemental analyses. The luminescence spectra are also recorded. According to the X-ray diffraction data, the calcium atom is coordinated by the oxygen atoms of the cucurbit[6]uril molecule, water molecules, and terephthalate anion (for I). The internal cavity of the cavitand is occupied by DMF.

Organic molecular composition of PM10 samples, collected at Chennai in tropical India, was studied using capillary gas chromatography/mass spectrometry. Twelve organic compound classes were detected in the aerosols, including aliphatic lipids, sugar compounds, lignin products, terpenoid biomarkers, sterols, aromatic acids, phthalates, hopanes, and polycyclic aromatic hydrocarbons (PAHs). At daytime, phthalates was found to be the most abundant compound class; while at nighttime, fatty acids was the dominant one. Concentrations of total quantified organics were higher in summer (611-3268 ng m-3, average 1586 ng m-3) than in winter (362-2381 ng m-3, 1136 ng m-3), accounting for 11.5±1.93% and 9.35±1.77% of organic carbon mass in summer and winter, respectively. Di-(2-ethylhexyl) phthalate, C16 fatty acid, and levoglucosan were identified as the most abundant single compounds. The nighttime maxima of most organics in the aerosols indicate a land/sea breeze effect in tropical India, although some other factors such as local emissions and long-range transport may also influence the composition of organic aerosols. The abundances of anhydrosugars (e.g., levoglucosan), lignin and resin products, hopanes and PAHs in the Chennai aerosols suggest that biomass burning and fossil fuel combustion are significant sources of organic aerosols in tropical India. Interestingly, terephthalic acid was maximized at nighttime, which is different from those of phthalic and isophthalic acids. A positive correlation was found between the concentration of 1,3,5-triphenylbenzene (a tracer for plastic burning) and terephthalic acid, suggesting that field burning of municipal solid wastes including plastics is a significant source of terephthalic acid. This study demonstrates that, in addition to biomass burning and fossil fuel combustion, the open-burning of plastics also contributes to the organic aerosols in South Asia.

Six new organotin carboxylates based on 1,3-benzenedicarboxylic acid and 1,4-benzenedicarboxylic acid derivatives, namely (Ph3Sn)2(2,5-L1)(C2H5OH)2 (1) (2,5-H2L1 = 2,5-dibenzoylterephthalic acid), (Ph3Sn)2(2,5-L2)(C2H5OH)2 (2) (2,5-H2L2 = 2,5-bis(4-methylbenzoyl)terephthalic acid), (Ph3Sn)2(2,5-L3)(C2H5OH)2 (3) (2,5-H2L3 = 2,5-bis(4-ethylbenzoyl)terephthalic acid), [(n-Bu2Sn)4(4,6-L1)O2(OH)(OC2H5)]22(C2H5OH) (4) (4,6- H2L1 = 4,6-dibenzoylisophthalic acid), [(n-Bu2Sn)4(4,6-L1)O2(OH)(OC4H9)]22(C4H9OH) (5) and [(n-Bu2Sn)4(4,6-L2)O2(OH)(OC2H5)]22(C2H5OH) (6) (4,6-H2L2 = 4,6-bis(4-methylbenzoyl)isophthalic acid), have been synthesized. All the organotin carboxylates have been characterized by elemental analysis, IR, 1H and 13C NMR spectroscopy and X-ray crystallography diffraction analyses. The...

It is a well known fact that sublimation substances, such as benzoic acid and terephthalic acid, are produced in the thermal decomposition of PET, and this causes problems in plastic recycling plants. However, it is clear that the addition of Ca(OH)2 affects the high selectivity of benzene without producing sublimation substances. The yield of benzene was 35.85 wt % at 700 °C and a 10.0 Ca(OH)2/PET molar ratio. This value means that the selectivity of benzene is 78.8% for liquid products, and 85.1 wt % for aromatic ring in input PET.   

Solubility switching of polymers is very useful in thin layer processing of conjugated polymers, as it allows for multilayer processing and increases the stability of the polymer. Acid catalyzed thermocleavage of ester groups from thiophene polymers carrying primary, secondary, and tertiary substituents have been examined by TGA?MS using different sulphonic acids. A substantial lowering of the cleavage temperature is observed, and the ester cleavage can even be performed in situ on roll?to?roll?coated films on polyethylene terephthalate (PET). © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Abstract Supramolecular polymers from the bolaamphiphilic L-histidine (BolaHis) and benzene dicarboxylic acids (o-phthalic acid, OPA; isophthalic acid, IPA and terephthalic acid, TPA) were found to form hydrogels although neither of the single components could gel water. It was suggested that the hydrogen bond and ionic interactions among different imidazole and carboxylic acid groups are responsible for the formation of the supramolecular polymer as well as the hydrogel formation. Depending on the structures of the dicarboxylic acids, different behaviors of the gels were observed. The hydrogels from OPA/BolaHis and IPA/BolaHis showed thixotropic properties, that is, the hydrogel was destroyed by hand shaking and then slowly gelated again at room temperature. However, the hydrogels of TPA/...

The production of a polyester-degrading hydrolase from the thermophilic actinomycete Thermomonospora fusca was investigated with regard to its potential technical application. Only in the presence of a polyester (random aliphatic-aromatic copolyester from 1,4-butanediol, terephthalic acid, and adipic acid with around 40-50 mol % terephthalic acid in the acid component), the excretion of the extracellular enzyme could be achieved with an optimized synthetic medium using pectin and NH(4)Cl as nitrogen source. Compared to complex media, a significantly higher specific activity at comparable volumetric yields could be obtained, thus reducing the expenditure for purification. The activity profile in the medium is controlled by a complex process involving (1) induction of enzyme excretion, (2) enzyme adsorption on the hydrophobic polyester surface, (3) inhibition of enzyme generation by monomers produced by polyester cleavage, and (4) enzyme denaturation. Diafiltration with cellulose acetate membranes as the sole downstream processing step led to a product of high purity and with sufficient yield (60% of total activity). Scaling-up from shaking flasks to a fermentor scale of 100 L revealed no specific problems. However, the excretion of the hydrolase by the actinomycete turned out to be inhibited by the degradation products (monomers) of the aliphatic-aromatic copolyester used as inductor for the enzyme production. The crude enzyme exhibited generally similar properties (temperature and pH optimum) as the highly purified hydrolase described previously; however, the storage capability and thermal stability is improved when the crude enzyme solution is diafiltrated. PMID:12363342

Abstract in english A new series of copolyamides CoPAs 7a-f were synthesized through the direct polycondensation reaction of 4,4'-azobenzenedicarboxylic acid 1 with 1,5-naphthalenediamine 2, 3,4-diaminobenzophenone 3 in the presence of adipic acid 4, fumaric acid 5 and terephthalic acid 6 as a second diacid in a medium consisting of N-methyl-2-pyrrolidone, triphenyl phosphate (TPP), calcium chloride and pyridine. The obtained polymers were characterized by means of FT-IR spectroscopy, elemen (more) tal analyses and inherent viscosity. These CoPAs were highly soluble in polar aprotic solvents such as N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), W-methyl-2-pyrrolidone (NMP) and other solvents such as sulfuric acid. Thermal properties of the CoPAs 7 c, 7d and 7e were investigated using thermal gravimetric analysis (TGA and DTG).

Pathways and enzymes of fatty acid synthase-mediated, long-even-chain (generally C16-C20) fatty acid synthesis are well studied, and general metabolism involved in short-chain (C4-C7) fatty acid biosynthesis is also understood. In contrast, mechanisms of medium-chain (C8-C14) fatty acid synthesis ar...

A commercial specimen of dimethylester of terephthalic acid (dimethylterephthalate or DMT) was studied on a Berlin wild line of Drosophila melanogaster. DMT was added to the nutrient medium on which the imagos fed or the flies developed from the stage of egg to imago. The genetic activity of the DMT was evaluated on the basis of its capability to cause dominant lethal mutations (DLM). It was found that though DMT is nontoxic for the imago it does have mutagenic effect, significantly increasing the level of DLM in the egg and subsequent stages of development of the Drosophila. 8 references.

Surface modification of high-density-polyethylene (HDPE), polypropylene (PP), and poly(ethylene terephthalate) (PET) films was promoted by potassium permanganate solutions in HCl acidic medium using eight conditions by varying time, temperature, and oxidative solution concentration. This oxidation system introduced different amounts of carbonyl-carboxyl and hydroxyl groups onto the polymer surfaces. Drop water contact angle, FTIR, TGA, and SEM were used to assess oxidation efficiency and the surface changes suffered by the polymer film. The hydrophilicity of films obtained by contact angle was analyzed using a 23 factorial design in Design-Expert program to obtain the main effects, the variance, and the interaction between the effects in action in the oxidation process.

High resolution 1H NMR spectra of terephthalic acid (TPA) ultrafine particles (UFP’s) were obtained by means of motional narrowing caused by Brownian motion of UFP’s in a liquid phase of CCl4. In the case of dispersing condition of UFP’s, highly resolved signals from benzoic protons were obtained at 6.85, 6.95, 7.08, 7.25, 7.50 and 7.65 ppm with respect to tetramethylsilane (TMS), even though only a signal at 8.15 ppm was obtained from moleculary dispersed TPA in acetone. Particle size was obtained to be ca. 15 nm by a dynamic laser scattering method.   

Sludges of various origin were analysed on the basis of microbial counts of anaerobes in order to investigate potential and alternative sources for inoculating anaerobic digestors. Sludges from neutralization and oil and fat separation tanks of a sugar cane factory, and from a stabilisation pond of a purified terephthalic-acid-producing plant were found to be adequate potential inocula. Activated sludges were found to have both hydrogenotrophic and acetoclastic methanogens and obligate hydrogen-producing acetogens (OHPA). In all sludges tested, hydrogenotrophic methanogens were the dominant strict anaerobes. The ratio between most probable number counts of acetoclastic methanogens and OHPA seems to be different between dispersed sludges and granular sludges. (orig.)

The glycolysis of postconsumer polyethylene terephthalate (PET) waste was evaluated with catalysts of zinc acetate, zinc stearate and zinc sulfate, showing that zinc acetate was the most soluble and effective. The chemical recycling by solvolysis of polylactic acid (PLA) and PET waste in either methanol or ethanol was investigated. Zinc acetate as a catalyst was found to be necessary to yield an effective depolymerization of waste PLA giving lactate esters, while with the same reaction conditions PET remains as an unconverted solid. This provides a strategy to selectively recycle mixed plastic waste by converting one plastic to a liquid and recovering the unreacted solid plastic by filtration.

Polyelectrolyte multilayer films were successfully assembled from each of the three charged derivatives of chitosan; N-[(2-hydroxyl-3-trimethylammonium)propyl]chitosan chloride (HTACC), N-succinyl chitosan (SCC) and N-sulfofurfuryl chitosan (SFC), paired with one of the two oppositely charged polyelectrolytes, poly(acrylic acid) (PAA) and poly(allylamine hydrochloride) (PAH) on surface-treated poly(ethylene terephthalate) (treated PET) substrates by alternate layer-by-layer adsorption. Surface coverage and wettability of the multilayer films were determined by AFM and water contact angle measurements, respectively. Analysis by quartz crystal balance with dissipation (QCM-D) has suggested that all multilayer films are relatively rigid and have a high water content associated within their st...

Fecal acidic sterol output has been found to be much lower than bile acid synthesis determined by isotope dilution. Because of this confusing discrepancy, we compared these 2 measurements done simultaneously on 13 occasions in 5 normal volunteers. In contrast to previous findings, bile acid synthesis by the Lindstedt isotope dilution method averaged 16.3% lower than synthesis simultaneously determined by fecal acidic sterol output (95% confidence limit for the difference - 22.2 to -10.4%). When one-sample determinations of bile acid pools were substituted for Lindstedt pools, bile acid synthesis by isotope dilution averaged 5.6% higher than synthesis by fecal acidic sterol output (95% confidence limits -4.9 to 16.1%). These data indicate that the 2 methods yield values in reasonably close agreement with one another. If anything, fecal acidic sterol outputs are slightly higher than synthesis by isotope dilution.

Both oxolinic acid and coumermycin A1, inhibitors of DNA gyrase, block DNA synthesis in Escherichia coli. At low concentrations of oxolinic acid, the rate of bacterial DNA synthesis first declines rapidly but then gradually increases. This gradual increase in synthesis rate depended on the presence ...

The synthesis of hexahydropyridazine-3-phosphonic acid (piperidazine-3-phosphonic acid) was performed via a hetero-Diels–Alder reaction followed by Lewis acid-catalyzed phosphonylation. This two-step procedure was improved to a one-pot reaction.   

The effect of a commercial styrene/butadiene/styrene-based compatibilizer (Styroflex) on the tensile and impact properties of ternary blends of poly(acrylonitrile-co-butadiene-co-styrene) (ABS), high impact poly(styrene) (HIPS) and poly(ethylene terephthalate-cocyclohexanedimethanol terephthalate) (...

...g., Polyethylene Terephthalate Film, Sheet, and Strip from the People's...unchanged in Polyethylene Terephthalate Film, Sheet, and Strip from the People's...55039 (September 24, 2008) (``PET Film''); see also Volume III of...

...terephthalate film, sheet and strip (PET Film) from Taiwan. The period of review...Film, Sheet and Strip from Taiwan (PET film): Nan Ya Plastic Corporation, Ltd...Terephthalate Film, Sheet and Strip (PET Film) from Taiwan: Supplemental...

...antidumping duty order on polyethylene terephthalate film (PET Film) from the United Arab Emirates.\\1\\ This review...pre- treated, or primed polyethylene terephthalate film (PET Film), whether extruded or co-extruded....

AbstractBiopolymer polylactic acid Pang, et al., Biotechnol. J. 2010, 5, 1125 1136 Polylactide (PLA) is a biodegradable, aliphatic polyester derived from lactic acid. It has similar mechanical properties to polyethylene terephthalate, but has a significantly lower maximum continuous use temperature. PLA products can be recycled after use, either by remelting and processing the material a second time or by hydrolyzing to lactic acid, the basic chemical. In this review by scientists from Changchun, China, technologies for polymerization of lactic acid and comparison of physical, thermal, and mechanical properties, biodegradability, and biocompatibility of the PLA and copolymers with other similar polymers are described. Biopolymer 1,3 propanediol Liu et al., Biotechnol. J. 2010, 5, 1137 1148...

The object of the study was to isolate and obtain x-ray diffraction analysis of the insoluble crystals which have been observed in Kevlar 49/H/sub 2/SO/sub 4/ dope. These insoluble crystals had previously been reported to be Kevlar single crystals after analysis by optical microscopy. A more detailed analysis does not support this conclusion. Additional optical microscopy coupled with FTIR and elemental analysis for C, H and N, has shown that these insoluble crystals are in fact terephthalic acid which is a decomposition product of the acid hydrolysis of Kevlar. A model compound study of sulfuric-acid hydrolysis of aromatic amide was carried out in order to better understand the sulfuric-acid-hydrolysis of Kevlar.

The ultrafine composite fibers based on the composites of binary fatty acid eutectics and polyethylene terephthalate (PET) with varied fatty acid eutectics/PET mass ratios (50/100, 70/100, 100/100 and 120/100) were fabricated using the technique of electrospinning as form-stable phase change materials (PCMs). The five binary fatty acid eutectics including LA-MA, LA-PA, MA-PA, MA-SA and PA-SA were prepared according to Schrader equation, and then were selected as an innovative type of solid-liquid PCMs. The results characterized by differential scanning calorimeter (DSC) indicated that the prepared binary fatty acid eutectics with low phase transition temperatures and high heat enthalpies for climatic requirements were more suitable for applications in building energy storage. The structura...

Fluorescent boronic acids are very useful for the design and synthesis of carbohydrate sensors. In an earlier communication, we first described the effort of developing water soluble fluorescent alpha-amidoboronic acids, which change fluorescence upon sugar binding. In this report, we describe a general method of functionalizing such boronic acids and their applications in the preparation of bis-alpha-amidoboronic acids with significantly enhanced binding for oligosaccharides as compared to their monoboronic acid counterparts. The advantages of good water solubility, easy modification to generate diversity, and modularity in synthesis will make alpha-amidoboronic acids very useful building blocks for future synthesis of boronic acid-based fluorescent sensors. PMID:20129789

We document an efficient and cost-effective synthesis of ramipril 1 utilizing (i) an environmentally benign process for the esterification of racemic 2-aza-bicyclo-[3.3.0]-octane-3-carboxylic acid hydrochloride 2 using boric acid as a catalyst and (ii) a robust resolution process for the synthesis of 3a by means of inexpensive and recyclable L-(+)-mandelic acid as key steps.

Sodium terephthalate (TA) produced from a PET pyrolysis product and waste glycerol (WG) from biodiesel manufacture were supplied to Pseudomonas putida GO16 in a fed-batch bioreactor. Six feeding strategies were employed by altering the sequence of TA and WG feeding. P. putida GO16 reached 8.70 g/l cell dry weight (CDW) and 2.61 g/l PHA in 48 h when grown on TA alone. When TA and WG were supplied in combination, biomass productivity (g/l/h) was increased between 1.3- and 1.7-fold and PHA productivity (g/l/h) was increased 1.8- to 2.2-fold compared to TA supplied alone. The monomer composition of the PHA accumulated from TA or WG was predominantly composed of 3-hydroxydecanoic acid. PHA monomers 3-hydroxytetradeeanoic acid and 3-hydroxytetradecenoic acid were not present in PHA accumulate...

The size of silver nanocrystals in polyol synthesis can be simply controlled by tuning the viscosity of the reaction medium such as ethylene glycol, 1,2-propanediol, 1,4-butanediol and 1,5-pentanediol. We found that a higher viscose medium (1,5-pentanediol) led to monodispersed smaller particles thanks to the slow addition of silver atoms into the nuclei. Size-controlled silver nanocrystals of 30 nm were obtained in a viscosity controlled medium of 1,5-pentanediol to synthesize a low refractive index filler by coating with silica and subsequent etching of the silver core. The coated low-reflection layer from the hollow silica nanoparticles on polyethylene terephthalate (PET) film can greatly reduce the reflection of the PET film from 10% to 2% over the entire visible region.

An effective one-pot synthesis of bis(dihydropyrimidinonoe)benzenes using chlorotrimethylsilane (TMSCl) through Biginelli condensation reaction of terephthalic aldehyde, 1,3-dicarbonyl compounds and (thio)urea or guanidine under microwave irradiation conditions is described. Excellent yields of the products and simple work-up are attractive features of this green protocol. Then, the cytotoxic activities of these compounds were evaluated on five different human cancerous cell lines (Raji, HeLa, LS-180, SKOV-3 and MCF7). Their cytotoxic study indicated that they possessed a weak to moderate activity. Furthermore, the higher activity of compound 4b bearing sulfur in C2 position of pyrimidinone ring showed the importance of this site for cytotoxic activity of these compounds. PMID:20102370

We report the synthesis of Ag nanoparticles in polyethylene terephthalate (PET) matrix using atom beam co-sputtering. Metal filling factor was evaluated by Rutherford backscattering spectrometry. Microstructural evolutions of the nanocomposites films were investigated by transmission electron microscopy, which confirmed the formation of irregular shaped Ag nanoparticles. The X-ray photoelectron spectroscopy measurements of the sputter deposited PET film and co-sputtered deposited Ag-PET as well as PET bulk foil (from Goodfellows) were performed to study chemical composition of the nanocomposite films. The optical properties of these nanocomposites were studied by light absorption/transmission, which revealed a narrow transmission of UV light approximately 320 nm and a broad surface plasmon resonance absorption extending up to infrared region (approximately 2400 nm). Swift heavy ion irradiation of Ag-PET nanocomposite resulted in narrowing the full width at half maximum of transmission band. PMID:20355509

Abstract Direct synthesis from an adapted salt coprecipitation of single-crystalline layered double-hydroxide (LDH) platelets can be realized by using polyvinylpyrrolidone (PVP) assisted by an organo-modifying agent, alginate (ALG). The formation of LDH inorganic platelets with a Zn/Al cation composition of 2:1 was demonstrated by TEM observations as well as by a topotactic restacking reaction that used the terephthalate molecule pillaring effect. From the perspective of PVP, LDH platelets can be viewed as hybrid filler. With regards to the inorganic platelets, the dispersive medium supplied by PVP chains in association with the biopolymer is an elegant process for generating single platelets, the whole of which can form an exfoliated polymer nanocomposite structure. The resulting transpar...

A water-activatable adhesive useful for adhering a solar film, polyester (polyethylene terephthalate) film, to glass or to metal substrates. The adhesive comprises the reacted product of (A) gamma-isocyanatopropyltriethoxy silane, containing a free isocyanate (NCO) group, and (B) a thermoplastic polyester formed by reacting (i) a dibasic acid selected from the group consisting of terephthalic acid, isophthalic acid and hexahydrophthalic acid, and mixtures thereof, with (ii) a polymethylene glycol of the formula HO(CH/sub 2/) /SUB x/ OH where x is an integer from 2 to 10, neopentyl glycol and glycerin, and mixtures thereof, and (iii) an aliphatic dibasic acid selected from the group consisting of those having the formula HOOC(CH/sub 2/) /SUB n/ COOH where n is an integer from 1 to 8, and mixtures of such acids, whereby substantially no free NCO remains in the adhesive. Solar film is used for absorbing and/or reflecting solar radiation. Solar film can be a single sheet of polyester dyed sufficiently to absorb the glare of bright sunlight, or it can be a single sheet of polyester, on one side of which a reflective metal (most often aluminum) is deposited in an amount which can be totally reflective or in an amount which still allows visible light transmission and over which a protective coating is deposited, or it can be a laminated structure of the reflective film adhered to a clear or dyed polyester film by which means the reflective metal is sandwiched between two layers of polyester film, or it can be a laminated structure of a reflective film to a polyolefin film.

hydrous chromium oxide, hydrous manganese dioxide, zirconium phos- phate, tin phosphate ... phosphate, titanium phosphate, molybdenyl ferrocyanide, zirconium ferrocyanide, ferric ..... exchange properties in acidic media. ll. Synthesis of ...

L-Amino acid ligase synthesizes various peptides from unprotected L-amino acids in an ATP-dependent manner. Known L-amino acid ligases catalyze only dipeptide synthesis, but recently we found that RizB of Bacillus subtilis NBRC 3134 catalyzes oligopeptide synthesis. In the present study, we searched for new members of the L-amino acid ligase group that catalyze oligopeptide synthesis. Several hypothetical proteins possessing the ATP-grasp motif were selected by in silico analysis. These recombinant proteins were assayed for L-amino acid ligase activity. We obtained five L-amino acid ligases showing oligopeptide synthesis activities. These proteins showed low similarity in amino acid sequence, but commonly used branched-chain amino acids, such as RizB, as substrates. Furthermore, the spr0969 protein of Streptococcus pneumoniae synthesized longer peptides than those synthesized by RizB, and the BAD_1200 protein of Bifidobacterium adolescentis showed higher activity toward aromatic amino acids than toward branched-chain ones. We also examined some of their characteristics.   

The effects of insulin on the synthesis of sterols and fatty acids and on the activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase (EC 1.1.1.34), a rate-limiting enzyme for sterol synthesis, were studied in mammalian cells grown in culture. While in some established cell lines sterol synthesi...

We describe a simple method for enzymatic synthesis of L and D amino acids from alpha-keto acids with Escherichia coli cells which express heterologous genes. L-amino acids were produced with thermostable L-amino acid dehydrogenase and formate dehydrogenase (FDH) from alpha-keto acids and ammonium f...

The simulated results by a computer were shown for the continous direct esterification in the first reactor between terephthalic acid (TPA) and ethylene glycol (EG) under reduced pressures in order to find the operational conditions in oligomer production of poly(ethylene terephthalate) with the lower content of diethylene glycol (DEG). It has been inferred from the results of simulation that the lower reaction pressure brings about the suppression of DEG formation due to the side reactions but it decreases the progress of esterification and polymerization due to main reactions. It has confirmed that the reaction mixtures of AV\\\\fallingdotseq0.6 eq kg?1 becomes a clear liquid without undissolved TPA (this point is the clearing point), independently of reaction conditions and the clearing point predicted from simulation results coincides with the experimental observation. Furthermore, a few cases of simulated results were applied for a commercial production plant in good agreement with the experimental results. The agreement suggests to support the validity of the present model for the precise predictions for a production plant.   

The biosynthesis of cyclopentenyl fatty acids from (2-cyclopentenyl)carboxylic acid (aleprolic acid) via chain-lengthening by C2-units was tested in seeds and leaves of Caloncoba echinata and Hydnocarpus anthelminthica of Flacourtiaceae and in various prepatations of higher plants other than Fla courtiaceae. Only tissues of Flacourtiaceae, where cyclopentenyl fatty acids are found naturally, were able to accept aleprolic acid as a starter molecule for the synthesis of cyclic fatty acids. Labelling patterns of straight chain and cyclic fatty acids, synthesized after incubation of Flacourtiaceae seeds with [1-(14)C[-acetate, indicated de novo synthesis of C16 fatty acids in either case, followed by elongation to higher homologs. PMID:990306

Poly (ethylene terephthalate)(dacron, PET) films were exposed under argon plasma glow discharge with different glows and induced polymerization of acrylic acid(AA) in order to introduce carboxylic acid group onto PET (PET-AA) assisted by ultraviolet radiation(UV). Hirudin-immobilized PET (PET-HRD) films were prepared by the grafting of PET-AA, followed by chemical reaction with hirudin. The surface structure of the treated PET was determined by X-ray photoelectron spectroscopy (XPS). The wettability, surface free energy, and interface free energy of the films were investigated by contact angle measurement. The blood compatibility of the films was assessed by platelet-adhesion test and fibrinogen conformational change measurements to evaluate the viability of the materials in biomedical engineering. Measurement by scanning electron microscopy (SEM) revealed that the amounts of adhered, aggregated and morphologically changed platelets were reduced on the hirudin-immobilized PET films. Enzyme-linked-immunoassay measurements that disclosed fibrinogen conformational changes showed results consistent with the platelets' behavior.

In this study, we fabricated optically transparent and electrically conductive multi-walled carbon nanotube (MWCNT) thin films using a spray-coating technique. The transparency and the electrical resistance of thin film are dependent on the nanotube content deposited on the polyethylene terephthalate (PET) substrate. Poly(acrylic acid) (PAA) and poly(N-vinyl pyrrolidone) (PVP) were used as adhesion promoters to improve MWCNT coating more significantly. The cross-linked polymer resulted in a superior bond between the MWCNTs and the substrates. The surface electrical resistance was significantly lower than the original sheet after nitric acid (HNO3) treatment because of the removed surfactant and the increased interconnecting networks of MWCNT bundles, thus improving the electrical and optic...

The polymerization of styrene was performed using two types of biradical compounds derived from 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO). The biradical compounds are diesters of 4-hydroxy-TEMPO with phthalic acid (o-TEMPO) and with terephthalic acid (p-TEMPO). When the polymerization was carried out by o-TEMPO and benzoyl peroxide (BPO) as an initiator, a polymer obtained had showed bimodal GPC. This suggests that dimerization by coupling of the polymers occurred during the polymerization. GPC demonstrated that the polymerization in the absence of BPO suppressed the dimerization and gave a polymer with narrow polydispersity. The polymerization was found to proceed in accordance with a living mechanism, because the molecular weight was directly proportional to the conversion, and was inversely proportional to the initial concentration of the biradical compound. A polystyrene obtained by the polymerization with the biradical compound initiated the polymerization of tert-butoxystyrene, giving ABA type of triblock copolymer.   

Abstract The 4-[4--(Hydrazinocarbonyl)phenoxy]-2-pentadecylbenzohydrazide was polycondensed with aromatic diacid chlorides viz., terephthalic acid chloride (TPC), isophthalic acid chloride (IPC), and a mixture of TPC : IPC (50 : 50 mol %) to obtain polyhydrazides which on subsequent cyclodehydration reaction in the presence of phosphoryl chloride yielded new poly(1,3,4-oxadiazole)s bearing flexibilizing ether linkages and pentadecyl side chains. Inherent viscosities of polyhydrazides and poly(1,3,4-oxadiazole)s were in the range 0.53-0.66 dL g-1 and 0.49-0.53 dL g-1, respectively, indicating formation of medium to reasonably high molecular weight polymers. The number average molecular weights (Mn) and polydispersities (Mw/Mn) of poly(1,3,4-oxadiazole)s were in the range 14,660-21,370 and 2...

Two Zn(II) and Cd(II) compounds with the in-situ generated ligand of 5-amino-tetrazolate (atz?) were prepared from the hydrothermal reactions of the corresponding Cd or Zn(II) salts with phenylcarboxylate, and characterized by elemental analysis, IR spectroscopy, and TGA. The results of X-ray crystallographic analysis reveal that compound [Zn2(BZA)(atz)2(OH)]n (1) (BZA=benzoic acid) presents a two-dimensional (2D) “hcb” topological network constructed from the ZnN2O2 tetrahedra. In compound [Cd6(atz)6(PTA)3]n (2) (PTA=terephthalic acid), the identical [Cd3(atz)3)]3+n clusters are connected by atz ligands to generate a 2D cationic layer, and the neighboring cationic layers are pillared by PTA giving birth to 3D network. After simplifying, the complicated 3D n...

Mixtures of poly(ethylene terephthalate) and magnesium carbonate at different weight ratios were heated up to 850 Formula Not Shown C in argon atmosphere. During heating, components of the initial mixtures underwent thermal decomposition yielding porous carbon materials loaded with different amounts of magnesium oxide. Structural characteristics of the prepared materials were determined from adsorption/desorption isotherms of nitrogen, measured at 77?K. For reference, portions of the products obtained were acid-washed to obtain MgO-free carbons. Pore structures of the prepared materials were strongly dependent on the quantitative compositions of starting mixtures. As a rule, specific surface areas determined for acid-washed materials were much higher than those for MgO-loaded carbons. The ...

The asymmetric hydrogenation of benzyl acetoacetate afforded benzyl (R)-3-hydroxybutanoate (II). Optically active ester-containing dicarboxylic acid V was newly prepared from II and terephthaloyl chloride, followed by debenzylation. The polycondensation of V with aromatic diamines was carried out in the presence of triphenyl phosphite, pyridine, and calcium chloride in N-methyl-2-pyrrolidone (NMP). The resulting optically active polyester-amides had inherent viscosities of 0.44–0.79 dl g?1, and specific rotations from ?43.6° to ?78.5°. The glass transition temperatures of the polymers were in the range from 129°C to 169°C, and their decomposition started at a temperature from 231°C to 249°C to afford biscrotonamide and terephthalic acid. The glass transition temperature of the optically active polymer derived from 4,4?-oxydianiline was 8°C higher than that of the corresponding inactive analogue.   

Purpose The purpose of this study was to assess the effect of polyethylene terephthalate (PET) on proliferation, differentiation, and attachment of ovine meniscocytes seeded in a hyaluronic acid/polycaprolactone biomaterial (BF-1) Methods BF-1 (30?% hyaluronic acid and 70?% polycaprolactone) cylinders with PET (CO-PET) or without PET, were seeded with 2x106 ovine meniscus cells. The specimens were harvested in triplets at 12 hours, seven, 14, 21 and 28?days. DNA content was measured to test proliferation, histological analysis for cell morphology, and biochemical assessment of glycosaminoglycan content and RT-PCR for type I and II collagen were used to assess differentiation, with immunohistochemistry as post-translational control. Attachment was evaluated by electronic microscopy at 28?da...

Polyfunctional 1-propenyl ether monomers (1a–c) were synthesized by the regioselective addition reaction of 1-propenyl glycidyl ether (PGE) with certain phosphonic dichlorides using quaternary onium salts as catalysts. The reaction of PGE with phenylphosphonic dichloride (PPDC) gave bis[1-(chloromethyl)-2-(propenyloxy)ethyl]phenylphosphonate (1a) in 82% yield. Polycondensation of 1a with terephthalic acid (TPC) was also carried out using 1, 8-diazabicyclo[5.4.0]undecene-7 (DBU) as a base to afford the corresponding polymer containing 1-propenyl ether groups (2a). A multifunctional monomer (3a) containing both 1-propenyl ether groups as Vc and methacrylate groups as Vr was prepared by the reaction of 1a with methacrylic acid (MA) using DBU. Photoinitiated cationic polymerization of these 1-propenyl ether compounds proceeded rapidly using bis[4-(diphenylsulfonio)phenyl]sulfide bis(hexafluorophoshate) (DPSP), as a cationic photoinitiator without solvent upon UV irradiation.   

The volume phase transition (VPT) behavior and the swelling properties of individual thermoresponsive poly(N-isopropylacrylamide) (PNIPAM)-based nanogels are investigated by in situ atomic force microscopy (AFM). Using a template-based synthesis method, cylindrical nanogels are synthesized for different polymerization times within nanopores (80 nm) of poly(ethylene terephthalate) (PET) track-etched membranes. The confinement conditions, characterized by the ratio ? between the average chain length and the pore diameter, are varied between 0.35 and 0.8. After dissolving the membranes, the volume of individual nanogels composed of PNIPAM-g-PET diblock copolymers is numerically extracted from AFM images while varying the water temperature from 28 to 44 °C. From the measured volumes, the swelling of nanogels is investigated as a function of both the water temperature and the confinement conditions imposed during the synthesis. Contrary to the VPT, the maximum swelling of the nanogels is strongly affected by these confinement conditions. The volume of nanogels in the swollen state can reach 1.1 to 2.1 times their volume in the collapsed state for a ratio ? of 0.8 and 0.5, respectively. These results open a new way to tune the swelling of nanogels, simply by adjusting the degree of confinement imposed during their synthesis within nanopores, which is particularly interesting for biomedical applications requiring a high degree of control over swelling properties, such as drug-delivery nanotools. PMID:22678885

Inducible and constitutive ?-galactosidase formation and radioactive amino acid incorporation were measured in cells recovering from various treatments which inhibit protein synthesis in the cell. Undelayed ?-galactosidase formation was found in stringent auxotrophs recovering from amino acid starva...

The reason why K10 is an efficient promoter for porphyrin synthesis is found to be due mainly to the mesoporosity rather than to the acid property of K10, by comparing K10 with progressively acid-treated montmorillonites.   

Solid-phase peptide synthesis in the N-to-C direction, opposite to the classical C-to-N direction of peptide synthesis, provides the synthetically versatile C-terminal carboxyl group for further modification into C-terminally modified peptide mimetics. These are of general interest as potential bioactive agents, particularly as protease inhibitors. Elaboration of peptide mimetics on the solid-phase would facilitate synthesis of peptide mimetic combinatorial libraries. This report describes an effective strategy for solid-phase inverse peptide synthesis based on readily available amino acid tert-butyl esters. The potential of this approach for peptide mimetic synthesis is demonstrated by the solid-phase synthesis of two peptide trifluoromethylketones.   

A new post-functionalization method for metal-organic frameworks (MOFs) has been developed to introduce acidity for catalysis. Upon treatment with a mixture of triflic anhydride and sulfuric acid, chemically stable MOF structures MIL-101(Cr) and MIL-53(Al) can be sulfated, resulting in a Broensted sulfoxy acid group attached to up to 50% of the aromatic terephthalate linkers of the structure. The sulfated samples have been extensively characterized by solid-state NMR, XANES, and FTIR spectroscopy. The functionalized acidic frameworks show catalytic activity similar to that of acidic polymers like Nafion{reg_sign} display in the esterification of n-butanol with acetic acid (TOF {approx} 1 min{sup -1} {at} 343 K). Water adsorbs strongly up to 4 molecules per sulfoxy acid group, and an additional 2 molecules are taken up at lower temperatures in the 1-D pore channels of S-MIL-53(Al). The high water content and Broensted acidity provide the structure S-MIL-53(Al) a high proton conductivity up to moderate temperatures.

In this perspective, an overview of our experiences on the application of samarium diiodide in organic synthesis for the preparation of amino acid and peptide analogues is presented. Three different carbon-carbon bond forming reactions are discussed, including side chain introductions, gamma-amino acid synthesis and acyl-like radical additions for the construction of C-C mimics of the peptidic bonds.

In this study, we investigated the roles of very long-chain fatty acid (VLCFA) synthesis by fatty acid elongase 3 (ELO3) in the regulation of telomere length and life span in the yeast Saccharomyces cerevisiae. Loss of VLCFA synthesis via deletion of ELO3 reduced telomere length, and reconstitut...

Skeletal muscle protein synthesis is elevated in neonates in part due to an enhanced response to the rise in insulin and amino acids after eating. In vitro studies suggest that glucose plays a role in protein synthesis regulation. To determine whether glucose, independently of insulin and amino acid...

Described is a short-step synthesis of optically active yamataimine, a 12-membered pyrrolizidine alkaloid of retronecine type. Methyl (1S,5R)-5-methyl-2-oxocyclopentanecarboxylate derived from (R)-(+)-pulegone was converted into the necic acid component required for the synthesis of yamataimine, in a nine-step sequence. Regioselective coupling of (+)-retronecine with the necic acid component via tin-mediated regioselective acylation followed by macrolactonization led to the first synthesis of (+)-yamataimine.   

Analysis of the fatty acid content of T.rubrum showed that the organism is capable of synthesizing a variety of saturated and unsaturated long-chain fatty acids (KOSTIW, VICHER & Lyon, 1966). The present study was undertaken to determine the mechanism of synthesis of these fatty acids. Experimental data point to the presence of two mechanisms of fatty acid synthesis in T. rubrum de novo synthesis and chain elongation. The presence of both mechanisms is suggested by the nature of the enzyme preparation, by the cofactor requirements for either pathway, and by the reaction products.

Plants provide aphids with unbalanced and low concentrations of amino acids. Likely, intracellular symbionts improve the aphid nutrition by participating to the synthesis of essential amino acids. To compare the aphid amino acid uptakes from the host plant and the aphids amino acid excretion into th...

Docosahexaenoic acid [22:6 omega 3; 22:6-(4,7,10,13,16,19)] is the major polyunsaturated fatty acid in the photoreceptor membranes of the retina and in cerebral gray matter. It must be obtained either from the diet or by synthesis from other omega 3 fatty acids, chiefly alpha-linolenic acid (18:3 om...

Small intestinal mucosal weight and nutrient absorption are significantly diminished early after cutaneous thermal injuries. Because these intestinal properties are highly dependent on rates of nucleic acid and protein synthesis, in vivo incorporation of thymidine, uridine, and leucine into small intestinal deoxyribonucleic acid, ribonucleic acid, and proteins were measured. Deoxyribonucleic acid synthesis was markedly decreased with the lowest thymidine incorporation in the jejunum (p less than 0.01); these findings were confirmed by autoradiographic identification of radiolabeled nuclei in the intestinal crypts. Protein synthesis was decreased by 6 h postinjury (p less than 0.01) but had returned to normal by 48 h. Consistent with a decreased rate of protein synthesis, ribonucleic acid synthesis was also decreased 18 h postinjury (p less than 0.01). These decreased deoxyribonucleic acid, ribonucleic acid, and protein synthesis rates are not likely a result of ischemia because in other studies of this injury model, intestinal blood flow was not significantly changed by the burn injury. Potentially, factors initiating the acute inflammatory reaction may directly inhibit nucleic acid and protein synthesis and lead to alterations in nutrient absorption and intestinal barrier function after injury.

The present study investigated the effect of active packaging, nitrogen flushing, container oxygen barrier and storage conditions on quality retention of raw whole unpeeled almonds. Almond kernels were packaged in: a) polyethylene terephthalate//low-density polyethylene (PET//LDPE), and b) low-density polyethylene/ethylene vinyl alcohol/low-density polyethylene (LDPE/EVOH/LDPE) pouches under N2, with or without an oxygen absorber, heat-sealed and stored for a period of 12 months. Quality parameters monitored were: peroxide value (PV), hexanal content, color, fatty acid composition and volatile compounds. PV ranged between 0.17 for fresh almonds and 9.22meqO2/kg oil for almonds packaged in PET//LDPE pouches under N2 exposed to light at 20degreeC after 12 months of storage. Respective values...

Ag2Mo4O13 photocatalyst was prepared by the hydrothermal method using AgNO3 and (NH4)2MoO4 as raw materials in one step. The Ag2Mo4O13 photocatalyst was characterized by X-ray powder diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) analysis, N2 adsorption measurements, and terephthalic acid photoluminescence (TA-PL) probing technique. The photocatalytic activity of the photocatalyst was evaluated by photocatalytic oxidation of methyl orange and photocatalytic reduction of nitrobenzene. The results showed that, the optimum catalyst concentration is 3g/L, and the optimum optical thickness is 49.4. When the reaction solution was illuminated for 60min and 10h, and the amount of photocatalyst was 2.0g/L, the methy...

The adsorption of terephthalic acid [C{sub 6}H{sub 4}(COOH){sub 2}, TPA] on a Pd(111) surface has been investigated by means of scanning tunneling microscopy (STM), x-ray photoelectron spectroscopy, and near-edge x-ray absorption fine structure spectroscopy under ultrahigh vacuum conditions at room temperature. We find the coexistence of one- (1D) and two-dimensional (2D) molecular ordering. Our analysis indicates that the 1D phase consists of intact TPA chains stabilized by a dimerization of the self-complementary carboxyl groups, whereas in the 2D phase, consisting of deprotonated entities, the molecules form lateral ionic hydrogen bonds. The supramolecular growth dynamics and the resulting structures are explained by a self-limiting deprotonation process mediated by the catalytic activity of the Pd surface. Our models for the molecular ordering are supported by molecular mechanics calculations and a simulation of high resolution STM images.

Abstract Summary: Vegetable fibers are being widely used as reinforcement in polymer composites. These composites can be applied in several fields, such as automotive, packaging and even construction. The polymer matrix used was synthesized from glycerol with phthalic and terephthalic acids in order to open future perspectives in the use of glycerin generated from the production of purified biodiesel. Composites with 2, 5, 10-wt% untreated and treated piassava fiber were obtained. Thermal, morphological and mechanical properties were evaluated. The tensile stress-strain curve of the polyester synthesized and composites was typical of a ductile material. SEM of the surface of fracture showed that the adhesion between fiber and matrix was enhanced after chemical treatment. However, the fiber...

Terephthalic acid disodium salt (TADS), C6H4(COONa)2, pyrolyzes in a solid phase at above 600°C. That pyrolysis produces a composite of carbon nanofibrils and fine sodium carbonate crystals. The carbon nanofibrils are amorphous and have 10-200 nm diameter. Forms of the carbon nanofibrils depend on experimental conditions. The carbon fibrils formed at 600°C are slightly entangled and bunched into bundles. Moreover, those bundles are aligned roughly in the direction parallel to the b-axis of the pristine TADS crystals. Wide-angle x-ray diffraction images of a pyrolytic product from a TADS crystal showed those arcs attributable to monoclinic sodium carbonate, indicating the rough alignment of the sodium carbonate crystals. Carbon nanofibrils are inferred to form as a result of exclusion by roughly aligned sodium carbonate crystals. [DOI: 10.1380/ejssnt.2005.484]   

The study was carried out to investigate the effect of different modified atmosphere packaging (MAP) techniques for extending the shelf-life of fresh-cut jackfruit (Artocarpus heterophyllus L.) bulbs kept under low temperature conditions. MAP carried out consisted of 3kPa O2+5kPa CO2 (with balance of N2) gas mixture flushed polyethylene (PE) bags, polyethylene terephthalate (PET) jars with silicon membrane window on lid and PE bag with air. Fresh-cut jackfruit bulbs were given a post-cutting phytosanitation wash followed by a dip pretreatment with calcium chloride, ascorbic acid and sodium benzoate under mild acidified conditions prior to MAP. Non-dipped samples packaged in same type of MAP conditions were used as control. Dip pretreatment along with different MAP was found effective in es...

Abstract Low-pressure plasma-polymerized ethylene film coatings rich in bonded oxygen groups (L-PPE:O) were deposited on poly(ethylene terephthalate; PET) in order to act as hosts for antimicrobial drugs. Increasing O2 content in the ethylene (C2H4)/Ar-diluted oxygen (O2) gas mixture reduced the deposition rate, but increased the concentration of bonded oxygen, [O], including that of carboxylic acid groups, [COOH], as determined by X-ray photoelectron- (XPS) and Fourier transform infrared (FTIR) spectroscopies, and by toluidine blue O (TBO) assays. L-PPE:O coatings took up and sustained the release of ciprofloxacin for several hours. Steric hindrance impeded vancomycin penetration into the cross-linked L-PPE:O coatings. Ciprofloxacin-loaded L-PPE:O coatings inhibited in vitro the growth of...

The purpose of this study was to solve some of the solid waste problems posed by plastics and concrete demolition. To this end, we evaluated the mechanical properties of polymer concrete, in particular, polymer concrete made of unsaturated polyester resins from recycled polyethylene terephthalate (PET) plastic waste and recycled concrete aggregates. The strength and the resistances to acid and alkali compounds of the polymer concrete were measured by varying the coarse and fine aggregate ratio and resin content. Three main observations followed the results. First, we found that the strength of polymer concrete made with a resin based on recycled PET and recycled aggregate increases with increasing resin content; however, beyond a certain resin content, the strength does not change apprecia...

A series of new fluorine-containing polyamides were prepared directly by polycondensation of 2-(4-trifluoromethylphenoxy)terephthalic acid with four trifluoromethyl-substituted aromatic bis(ether amine)s in N-methyl-2-pyrrolidone (NMP) solution containing dissolved calcium chloride using triphenyl phosphite and pyridine as condensing agents. All the polymers showed excellent solubility in solvents such as NMP, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, pyridine, tetrahydrofuran, and acetone at room temperature. These polymers had inherent viscosities between 0.67 and 1.09 dL/g, and their weight-average molecular weights and number-average molecular weights were in the range of 48,200?68,000 and 29,500?39,400, respectively. The resulting polymers showed glass-transiti...

Poly(ethylene terephthalate) (PET) is one of the most used commodity polymers, especially for food and beverage applications, and its recycling is of great importance because of the possible use in the textile and construction industries. On the other hand, the interest in biodegradable polymers has led, in recent years, to the use of materials such as poly(lactic acid) (PLA) also in the food and beverage industry. The presence of small amounts of PLA in the PET waste can significantly affect the post-consumer recycling process. In this work, the effect of the presence of small amounts of PLA on the recycling of PET bottles is investigated by rheological, mechanical, morphological and thermogravimetric analysis. The results indicate that this presence can significantly affect the rheologic...

Chitosan/poly (vinyl pyrollidone) (CHI/PVP) coatings were prepared to improve the antibacterial properties of poly (ethylene terephthalate) (PET) by a simple dip-coating method. The binding capability of CHI/PVP coatings was enhanced by successively pretreatment of PET by polyetherimide and polyacrylic acid and crosslinking. Measurements of water contact angle and atomic force microscope revealed that the coatings created a highly hydrophilic surface with low roughness. Adherences of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) on PET with CHI/PVP coating were significantly reduced. Bactericidal activity of CHI/PVP coatings was good against E. coli and S. aureus and the adding of PVP obviously increased its antiadhesion property. In vitro cytotoxicity tests, cell morphology and activity evaluation of human umbilical vein endothelial cells showed that CHI/PVP coatings had good biocompatibility.

Conformation change occurring during the formation of the liquid crystalline phase was investigated by using the in situ Fourier transform infrared spectroscopy. An isotropic glass of a random liquid crystalline copolyester consisting of 60 mol% p-hydroxybenzoic acid/40 mol% ethylene terephthalate was prepared with the cast from a solution and was heated from the room temperature up to 300°C. The onset of the transformation from the gauche conformers to the trans conformers of the ethylene glycol group was observed at ca. 60°C. The change in packing was indicated by the change in the intensity of the bands assignable to the aromatic rings around 150°C. Liquid crystalline phase formation observed with the optical method started to occur at ca. 200°C in association with the loss of the packing.   

PET/BPA copolymer of terephthalic acid, bisphenol-A and ethylene glycol was melt-pressed and quenched in ice water. This copolymer film was drawn by capillary rheometer. Shrinkage, crystallinity, morphology, thermal, dynamic mechanical, and mechanical properties of these copolymer films were investigated. The PET/BPA copolymer film exhibited T{sub m} lower than that of PET film. The crystallinity and density of these drawn copolymer films increased with draw ratio and draw rate but decreased with draw temperature. The tensile strength and tensile modulus of the copolymer films increased with draw ratio but decreased with draw temperature. Shrinkage of the drawn copolymer film decreased with draw ratio and draw rate. (author). 32 refs., 17 figs.

Ultraviolet (UV)-induced graft copolymerization of allyl acetate (AA) monomer onto poly(ethylene terephthalate) (PET) films and the subsequent sulfonation on the monomer units in the grafting chain using chlorosulfonic acid (ClSO3H) were carried out to prepare proton exchange membranes (PEMs) for fuel cells. A maximum grafting value of 12.8% was found for 35 vol% allyl acetate after 3 h radiation time. Optimum concentration of ClSO3H was selected for the sulfonation reaction to be 0.05 mol/L based on the degree of sulfonation and the tensile strength studies of the membrane. The degree of sulfonation increased as the sulfonation reaction temperature and sulfonation time were increasing. The radiation grafting and the sulfonation have been confirmed by titrimetric and gravimetric analyses a...

Polymers are largely studied for use in PEM-type fuel cell (Proton Exchange membrane, PEMFC). These fuel cells are based on polymer membranes as electrolyte, also called protons conductor. This work developed co-polyesters made electrical conductors by doping with sodium dodecyl sulfate. The copolymers were synthesized from the copolymerization of terephthalic and adipic acids with glycerol. The material was processed in a reactor and shaped by hot pressing, yielding homogeneous and flexible plates, with excellent surface finish. The co-polyesters were analyzed by SEM, FTIR, TG, DSC, and XRD. The thermal analysis showed that the composites were thermally stable up to about 250 deg C. The micrographics revealed the MDS homogeneously dispersed in the polymeric matrix. These copolymers showed electrical conductivity between 10-7 to 10-1 S/cm, suggesting strong potential use in PEM fuel cells. (author)

A natural Citrus extract with potential antioxidant activity was evaluated as an ingredient for the production of active food packaging. The extract, in methanol, was sprayed onto the surface of polyethylene terephthalate (PET) trays. For comparison, a second set of trays were prepared using @a-tocopherol as the coating. The effectiveness of the two types of packaging in delaying lipid oxidation in cooked turkey meat slices, stored at 4^oC over 4 days, was compared using 2-thiobarbituric acid-reactive substances (TBARS) and hexanal assays. TBARS and hexanal values, for meat stored on the Citrus extract coated trays, were significantly lower (P<0.01) than those of meat stored on uncoated (control) trays while @a-tocopherol coated trays exhibited no significant effect compared to control tra...

Abstract A novel polymeric flame retardant (FR) with phosphorous-nitrogen pendent groups (PVP-P-DCA) was synthesized by polyvinyl alcohol (PVA), phosphoric acid, and dicyandiamide (DCA). Its structure was characterized by FTIR, 1H, 13C, 31P NMR, elemental analysis and TG. Poly(ethylene terephthalate) (PET)/cotton blends (T/C) was treated via pad-dry-cure process with PVP-P-DCA. The surface of FR-T/C was characterized by FTIR and SEM. The fabric performance was examined by whiteness and tensile property. The fire behavior was performed by limited oxygen index (LOI), vertical burning test, cone calorimetry test. The durability effect, thermal stability, and flame retardancy mechanism of the treated T/C were investigated by TGA, FTIR, and SEM. The results show that PVP-P-DCA is not only an ef...

2-Pyrone-4,6-dicarboxylic acid (PDC), a chemically stable metabolic intermediate of lignin, its bis(hydroxyethyl) derivative (BHPDC) and bis(hydroxyethyl) terephthalate (BHT) were polymerized to prepare the corresponding polyesters carrying the oxyethyleneoxycarbonyl(2-pyrone-4,6-diyl)carbonyl and oxyethyleneoxy-terephthaloyl units [x and y units, resp., x+y=1] by polycondensation eliminating water and/or 1,2-ethanediol molecules. The polyesters were mostly stable up to 210 °C, after that the degradation of pyrone ring commenced. These polyesters exhibited strong adhering properties against metal, glass and surfaces with increasing the x unit content to 0.4–0.6, such as about 50–60 MPa for SUS/polyester/SUS or Al/polyester/Al samples, by the JIS K 6849:1994 testing method of tensile strength. As the fracturing plane was the midst of the polyester layer and at the interface, the polyester was tenaciously adhering to the metal surface.   

Supramolecular polymers from the bolaamphiphilic L-histidine (BolaHis) and benzene dicarboxylic acids (o-phthalic acid, OPA; isophthalic acid, IPA and terephthalic acid, TPA) were found to form hydrogels although neither of the single components could gel water. It was suggested that the hydrogen bond and ionic interactions among different imidazole and carboxylic acid groups are responsible for the formation of the supramolecular polymer as well as the hydrogel formation. Depending on the structures of the dicarboxylic acids, different behaviors of the gels were observed. The hydrogels from OPA/BolaHis and IPA/BolaHis showed thixotropic properties, that is, the hydrogel was destroyed by hand shaking and then slowly gelated again at room temperature. However, the hydrogels of TPA/BolaHis could not. Interestingly, when Eu(III) was doped into IPA/BolaHis supramolecular polymers, very strong luminescence enhancement was observed. FT-IR spectroscopies and XRD analysis revealed that the strong luminescence enhancement could be attributed to the matched supramolecular nanostructures, which render the correct binding and a good dispersion of Eu(III) ions. The work offers a new approach for fabricating functional hydrogels through the supramolecular polymers. PMID:23097314

Two new naphthalene ring-containing diamino-diesters, 2,7-bis(4-aminobenzoyloxy)naphthalene (p-2) and 2,7-bis(3-aminobenzoyloxy)naphthalene (m-2), were synthesized from the condensation of 2,7-dihydroxynaphthalene with 4-nitrobenzoyl chloride and 3-nitrobenzoyl chloride, respectively, followed by catalytic hydrogenation. Two series of naphthalene-containing poly(ester amide)s with inherent viscosities of 0.49–0.97 and 0.36–0.73 dL g-1 were prepared by the phosphorylation polyamidation of p-2 and m-2, respectively, with various aromatic dicarboxylic acids. Most of the poly(ester amide)s had excellent solubilities in polar aprotic solvents such as N-methyl-2-pyrrolidone and N,N-dimethylacetamide, especially for the m-series polymers. Some of the poly(ester amide)s could be cast into transparent, flexible, and tough films from DMAc solutions. The poly(ester amide)s derived from rigid dicarboxylic acids such as terephthalic acid, 4,4’-biphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid and 4,4’-sulfonyldibenzoic acid were semicrystalline and showed less solubility. Except for three examples, most of the poly(ester amide)s displayed discernible glass transitions between 187 and 237 °C in the DSC traces. These poly(ester amide)s showed insignificant decomposition below 400 °C in nitrogen or air. The investigation of the thermal decomposition of the poly(ester amide)s using infrared spectroscopy and pyrolysis-gas chromatography/mass spectrometry (pyrolysis-GC/MS) indicated that the primary breakage of the ester linkages started at around 400 °C, which initiated the polymer chain scission.   

...A-570-929: Polyethylene Terephthalate (``PET'') Film from the People's Republic of China. Requestor...Company (``CFC''); CFC's Amorphous PET (``APET''), Glycol-modified PET (``PETG''), and coextruded APET and...

Methods for the synthesis of 1-aminocyclopropane-1,2-dicarboxylic acid derivatives including carbo- and heterocyclic compounds and peptides are analysed. Special attention is given to methods for the synthesis of individual stereoisomers of 1-aminocyclopropane-1,2-dicarboxylic acid derivatives based on the use of diastereoselective processes or enantiomerically pure starting compounds. The transformations of 1-aminocyclopropane-1,2-dicarboxylic acid derivatives which yield compounds with potential biological activities are considered.

The efficacy of various supported heteropoly acids in synthesis of mandelates from mandelic acid and alcohols is investigated. Dodecatungestophosphoric acid (PW) supported on silica gives the best yield in short reaction times. The present procedure represents a clean, practical, simple, mild, time-saving, and eco-friendly method for synthesis of mandelates in short reaction times and excellent yields with 100% selectivity. The catalyst is found to be stable, highly efficient, reusable, and inexpensive during all runs.

Di(2-ethylhexyl) terephthalate (DEHT), the 2-ethylhexyl diester of terephthalic acid (1,4-benzenedicarboxylic acid) was administered in the diet to groups of 20 male and female Sprague-Dawley rats for 90 days at 1.0, 0.5, 0.1 or 0.0% by weight. No major organ or systemic toxicity resulted from consumption of the diets in any group of animals. Changes that were observed included slight effects on some haematology parameters including haemoglobin, haematocrit, mean corpuscular volume and mean corpuscular haemoglobin at the 1.0% dose; and slight increases in relative liver weights (11.2% in the males, 8.9% in the females), also at the 1.0% dose level. Marginal changes of less than 3% in some red blood cell indices were observed at the 0.5% dietary dose level; however no anaemia or changes in relative liver weights were observed at this dose level. Thus, no significant adverse effects attributable to the test material were identified in animals consuming the two lower doses. In a morphometric study of liver sections, DEHT was found not to induce hepatic peroxisomes at the 1.0% dose level. The positive control material (2-ethylhexanol at 1000 mg/kg, 5 days/wk for 3 wk), produced a 30% increase in liver-to-body weight ratio, and increases in peroxisome cell fraction, and in peroxisome density. The no-effect levels of DEHT in rats consuming the material for 90 days in the diet were 277 and 309 mg/kg/day in males and females, respectively. These results are contrasted with those reported for di(2-ethylhexyl) phthalate (DEHP) in similar feeding studies. While DEHP at 1% in the diet is reported to produce significant effects on the liver, testes, kidney, brain, stomach and adrenal weights, DEHT has been shown in this study to have only a minor effect on liver weight in 90 days at 1.0% in the diet. PMID:7590545

This review outlines information about the Gram-negative, aerobic bacterium Variovorax paradoxus. The genomes of these species have G+C contents of 66.5-69.4 mol%, and the cells form yellow colonies. Some strains of V. paradoxus are facultative lithoautotrophic, others are chemoorganotrophic. Many of them are associated with important catabolic processes including the degradation of toxic and/or complex chemical compounds. The degradation pathways or other skills related to the following compounds, respectively, are described in this review: sulfolane, 3-sulfolene, 2-mercaptosuccinic acid, 3,3'-thiodipropionic acid, aromatic sulfonates, alkanesulfonates, amino acids and other sulfur sources, polychlorinated biphenyls, dimethyl terephthalate, linuron, 2,4-dinitrotoluene, homovanillate, veratraldehyde, 2,4-dichlorophenoxyacetic acid, anthracene, poly(3-hydroxybutyrate), chitin, cellulose, humic acids, metal-EDTA complexes, yttrium, rare earth elements, As(III), trichloroethylene, capsaicin, 3-nitrotyrosine, acyl-homoserine lactones, 1-aminocyclopropane-1-carboxylate, methyl tert-butyl ether, geosmin, and 2-methylisoborneol. Strains of V. paradoxus are also engaged in mutually beneficial interactions with other plant and bacterial species in various ecosystems. This species comprises probably promising strains for bioremediation and other biotechnical applications. Lately, the complete genomes of strains S110 and EPS have been sequenced for further investigations. PMID:23192768

Regulation of exocellular enzyme acid phosphatase 2 synthesis is studied. 21 mutants with consitutive synthesis of this enzyme are obtained by UV-irradiation. All mutants were recessive and were distributed among 3 complementation groups ACP80, ACP81, ACP82. Two groups, ACP80 and ACP81 corresponded to two different genes, which showed no linkage with ACP1, ACP2 and PHO1 genes. The type of synthesis of acid phosphatase 2 in strains acp1 acp80, acp1 acp81, acp2 acp80, acp2 acp81 is determined, and a conclusion is made about the participation of ACP2 gene in the regulation of acid phosphatase 2 synthesis. It is shown that some mutations in PHO1 gene, which block the activity of acid phosphatase 1, influence the activity and regulation of acid phosphatase 2. PMID:765203

The synthesis of glucose oxidase and catalase by Aspergillus niger was investigated using a resting cell culture system without growth being established. Calcium carbonate induced the synthesis of both enzymes and calcium chloride inhibited it. The optimal pH for the biosynthesis of glucose oxidase and catalase was 6.0 and 5.7, respectively. The effects of other bivalent cations, reductive compounds and metabolic products on enzyme synthesis were also tested. The biosynthesis of glucose oxidase and catalase was promoted by MnCO3, thioglycolic acid, pyroracemic acid and gluconic acid. PMID:10701992

As part of a research program on nucleotide metabolism in potato tubers (Solanum tuberosum L.), profiles of pyridine (nicotinamide) metabolism were examined based on the in situ metabolic fate of radio-labelled precursors and the in vitro activities of enzymes. In potato tubers, [(3)H]quinolinic acid, which is an intermediate of de novo pyridine nucleotide synthesis, and [(14)C]nicotinamide, a catabolite of NAD, were utilised for pyridine nucleotide synthesis. The in situ tracer experiments and in vitro enzyme assays suggest the operation of multiple pyridine nucleotide cycles. In addition to the previously proposed cycle consisting of seven metabolites, we found a new cycle that includes newly discovered nicotinamide riboside deaminase which is also functional in potato tubers. This cycle bypasses nicotinamide and nicotinic acid; it is NAD --> nicotinamide mononucleotide --> nicotinamide riboside --> nicotinic acid riboside --> nicotinic acid mononucleotide --> nicotinic acid adenine dinucleotide --> NAD. Degradation of the pyridine ring was extremely low in potato tubers. Nicotinic acid glucoside is formed from nicotinic acid in potato tubers. Comparative studies of [carboxyl-(14)C]nicotinic acid metabolism indicate that nicotinic acid is converted to nicotinic acid glucoside in all organs of potato plants. Trigonelline synthesis from [carboxyl-(14)C]nicotinic acid was also found. Conversion was greater in green parts of plants, such as leaves and stem, than in underground parts of potato plants. Nicotinic acid utilised for the biosynthesis of these conjugates seems to be derived not only from the pyridine nucleotide cycle, but also from the de novo synthesis of nicotinic acid mononucleotide. PMID:19820966

A method of synthesis of pseudo-?-aminobutanoyl peptides and other phosphinic analogs of ?-aminobutyric acid from hypophosphites is suggested. Silyl phosphonites formed by in situ addition of bis-(trimethylsilyl) hypophosphite to the corresponding ?-substituted acrylates, styrene, or vinyl phosphonate used as unsaturated components in the synthesis react in situ with N-(?-bromoalkyl)phthalimides by an Arbuzov reaction scheme, affording ?-(phthalimido)alkylphosphinic acids possessing ?-substituted ?-(alkoxycarbonyl)ethyl, ?-phenylethyl, or ?-(diethoxyphosphinoyl)ethyl substituents. Acid hydrolysis of these reaction products gives the target aminophosphinic acids: phosphinic analogs of ?-aminobutyric acid.

The research has involved the characterization of catalyst acidity, {sup 2}D NMR studies of Bronsted acid sites, and kinetic, calorimetric, and spectroscopic studies of methylamine synthesis and related reactions over acid catalysts. Approach of this work was to explore quantitative correlations between factors that control the generation, type, strength, and catalytic properties of acid sites on zeolite catalysts. Microcalorimetry, thermogravimetric analysis, IR spectroscopy, and NMR spectroscopy have provided information about the nature and strength of acid sites in zeolites. This was vital in understanding the catalytic cycles involved in methylamine synthesis and related reactions over zeolite catalysts.

Recent advances in nucleic acid sequencing, structural, and computational technologies have resulted in dramatic progress in our understanding of nucleic acid structure and function in the cell. This knowledge, together with the predictable base-pairing of nucleic acids and powerful synthesis and expression capabilities now offers the unique ability to program nucleic acids to form precise 3D architectures with diverse applications in synthetic and cell biology. The unique modularity of structural motifs that include aptamers, DNAzymes, and ribozymes, together with their well-defined construction rules, enables the synthesis of functional higher-order nucleic acid complexes from these subcomponents. As we illustrate here, these highly programmable, smart complexes are increasingly enabling...

Abstract Nucleic acid-encoded libraries are emerging as an attractive and highly miniaturized format for the rapid identification of protein ligands. An important criterion in the synthesis of nucleic acid encoded libraries is the scope of reactions that can be used to introduce molecular diversity and devise divergent pathways for diversity-oriented synthesis (DOS). To date, the protecting group strategies that have been used in peptide nucleic acid (PNA) encoded synthesis (PES) have limited the choice of reactions used in the library synthesis to just a few prototypes. Herein, we describe the preparation of PNA monomers with a protecting group combination (Mtt/Boc) that is orthogonal to Fmoc-based synthesis and compatible with a large palette of reactions that have been productively used...

We present here a new, general, solid phase strategy for the synthesis of sequence independent peptidyl-fluoromethyl ketones using standard Fmoc peptide chemistry. Our method is based on the synthesis of bifunctional linkers which allows the incorporation of amino acid fluoromethyl ketone unit at the C-terminal end of peptide sequences. Application of this approach for the synthesis of activity based probes for SENPs is also described. PMID:22543859

The efficient synthesis of 3-O-thia-cPAs (4a-d), sulfur analogues of cyclic phosphatidic acid (cPA), has been achieved. The key step of the synthesis is an intramolecular Arbuzov reaction to construct the cyclic thiophosphate moiety. The present synthetic route enables the synthesis of 4a-d in only four steps from the commercially available glycidol. Preliminary biological experiments showed that 4a-d exhibited a similar inhibitory effect on autotaxin (ATX) as original cPA.

A facile one-pot synthesis of polysubstituted quinoline derivatives has been demonstrated by using sulfamic acid as a reusable catalyst under solvent-free conditions. The synthetic method provides the basis and advantages of a simple experimental procedure and easy recovery and reuse of catalyst, which makes it a highly practical and environmentally benign pathway for the synthesis of polysubstituted quinolines. Interestingly, this one-pot synthesis could produce the products regioselectively in the presence of dis-symmetrical arylamines. Graphical abstract

Our previous research concerning anti-rice blast fungus substances from the rice plants has led to the isolation of various types of oxygenated fatty acids as exemplified by 9,12,13-trihydroxy C-18 fatty acid. The fatty acids play an important role in the defense of the rice plants against this fungus. For evaluation of biological activity, we needed the isomeric trihydroxy fatty acids. This paper describes the synthesis of four stereoisomers of 9,10,13-trihydroxy fatty acid.   

The synthesis of 2,5-dihydroxy(carboxy-/sup 14/C)benzoic acid (gentisic acid) is described. The procedure utilized (carboxy-/sup 14/C)salicylic acid as a starting material. Salicylic acid was converted to gentisic acid using potassium persulfate hydroxylation. The mixture of hydroxylation products in this reaction was easily separated by UV-visualized quartz column chromatography to obtain the desired isomer in high purity (overall yield of 38%). This procedure may be used for micro and semimicro preparation of the title compound.

Acid brings the oxygen: A general method for palladium catalyzed C?H oxygenation has been developed for the facile synthesis of a wide range of functionalized phenols with readily available aryl ketones, benzoates, benzamides, acetanilides, and sulfonamides. A trifluoroacetic acid/trifluoroacetic acid anhydride solvent system serves as the oxygen source and is the critical factor for C?H activation. PMID:23161485

The effects of low extracellular pH and intracellular accumulation of weak organic acids were compared with respect to fatty acid synthesis by whole cells of Mycobacterium tuberculosis and Mycobacterium smegmatis. The profile of fatty acids synthesized during exposure to benzoic, nicotinic, or pyraz...

Activation of carboxylic acids with N,N'-carbonyldiimidazole followed by the reaction with anhydrous or aqueous hydroxylamine hydrochloride was demonstrated to be an operationally simple method for the synthesis of hydroxamic acids in good yield and high purity after aqueous workup. The potential by-product, N,O-diacylhydroxylamine, is cleanly transformed to hydroxamic acid in these reaction conditions.

An amino acid type poly(ethylene glycol) is a useful tool for preparation of a bi- or multivalent poly(ethylene glycol) hybrid of bioactive peptides, but synthesis is problematic. The amino acid type poly(ethylene glycol) was prepared from poly(oxyethylene)diglycolic acid followed by introduction of a fluorenylmethyloxycarbonyl group. The resulting product could be purified easily by LH-20 column chromatography and HPLC.   

An efficient synthesis of selenothiophosphinic acid salts is achieved by reacting selenothiophosphinic acid S-(2-trimethylsilyl)ethyl esters with ammonium or alkali metal fluorides. The X-ray structure analysis of the potassium 18-crown-6 selenothiophosphinic acid salt shows that the salt is monomeric. Alkylation of the salts proceeds at the selenium atom whereas acylation occurs at the sulfur atom.   

Copper-catalyzed synthesis of N-aryl anthranilic acid derivatives using effective amination of 2-chloro and 2-bromobenzoic acid under microwave irradiation is reported. Some of the advantages of this method are high chemoselectivity, short reaction times, ease of work up procedure and elimination of the need for acid protection.

The self-metathesis of readily available monounsaturated fatty acids has the potential of being an important pathway for the synthesis of symmetrical long-chain unsaturated-alpha, omega-dicarboxylic acids (C18-C26). Previous studies on the self-metathesis of monounsaturated fatty acid esters using ...

[15-13C2H3]-Dihydroartemisinic acid (3a) and [15-13CH3]-dihydro-epi-deoxyarteannuin B (7b), intended for evaluation in vivo as biosynthetic precursors to artemisinin, have been obtained from a reconstructive synthesis. The decalenone acid 8 from acid degradation of artemisinin (1) serves as a common...

A number of bridged nucleic acids with conformationally locked sugar moiety were synthesized from the readily accessible sugar derivatives. The conformations of the sugar moiety of the bridged nucleic acids (BNAs) are locked to either N-type or S-type sugar puckering. This article summarizes the synthesis of these nucleic acid analogues.     Fullsize Image

The highly efficient synthesis of ?-aminophosphoryl compounds with one and two ethylphosphoryl groups was performed by the addition of amines to the vinylphosphoryl compounds in water as a solvent. The acid-base properties and membrane-transport abilities of the target compounds towards carboxylic acids were studied. Selectivity towards acetic acid was revealed.

The structures of the 1:1 proton-transfer compounds of isonipecotamide (piperidine-4-carboxamide) with 4-nitrophthalic acid [4-carbamoylpiperidinium 2-carboxy-4-nitrobenzoate, C6H13N2O8+C8H4O6-, (I)], 4,5-dichlorophthalic acid [4-carbamoylpiperidinium 2-carboxy-4,5-dichlorobenzoate, C6H13N2O8+C8H3Cl2O4-, (II)] and 5-nitroisophthalic acid [4-carbamoylpiperidinium 3-carboxy-5-nitrobenzoate, C6H13N2O8+C8H4O6-, (III)], as well as the 2:1 compound with terephthalic acid [bis(4-carbamoylpiperidinium) benzene-1,2-dicarboxylate dihydrate, 2C6H13N2O8+C8H4O42-2H2O, (IV)], have been determined at 200-K. All salts form hydrogen-bonded structures, viz. one-dimensional in (II) and three-dimensional in (I), (III) and (IV). In (I) and (III), the centrosymmetric R22(8) cyclic amide-amide association is fou...

In man bile acid synthesis has a distinct circadian rhythm but the relationship of this rhythm to feedback inhibition by bile acid is unknown. We measured bile acid synthesis as release of 14CO2 from (26-14C)cholesterol every 2 hr in three normal volunteers during five separate 24-hr periods. Data were fitted by computer to a cosine curve to estimate amplitude and acrophase of the circadian rhythm. In an additional six volunteers, we measured synthesis every 2 hr from 8:00 a.m. to 4:00 p.m. only. During the control period, amplitude (expressed as percentage of mean synthesis) averaged 52% and acrophase averaged 6:49 a.m. During administration of ursodeoxycholic acid (15 mg per kg per day), synthesis averaged 126% of baseline (p less than 0.1), amplitude averaged 43% and acrophase averaged 6:20 a.m. During administration of chenodeoxycholic acid (15 mg per kg per day), synthesis averaged 43% of baseline (p less than 0.001), amplitude averaged 53% and acrophase averaged 9:04 a.m. Addition of prednisone to this regimen of chenodeoxycholic acid to eliminate release of 14CO2 from corticosteroid hormone synthesis resulted in a mean amplitude of 62% and a mean acrophase of 6:50 a.m., values very similar to those in the baseline period. Administration of prednisone alone also did not significantly alter the baseline amplitude (40%) or acrophase (6:28 a.m.). We conclude that neither chenodeoxycholic acid nor ursodeoxycholic acid significantly alters the circadian rhythm of bile acid synthesis in man.

The total chemical synthesis of a protein provides atomic-level control over its covalent structure, however polypeptides prepared by solid phase peptide synthesis are limited to approximately fifty amino acid residues. This limitation has been overcome by 'Native Chemical Ligation‘, which involves ...

Two ways for the synthesis of binaphthyl were examined based on a chiral ligand-mediated asymmetric conjugate addition of 1-naphthyllithium to naththalene-2-carboxylic acid 2,6-di-t-butyl-4-methoxyphenyl esters. The one pot method by conjugate addition-elimination gave a relatively higher enantioselectivity than the two step synthesis based on addition and subsequent oxidative aromatization.   

This paper describes the synthesis and characterization of a novel mesostructured solid electrolyte composite material, denoted meso-SiO2-C12EO10OH-CF3SO3H. A lyotropic non-ionic surfactant-triflic acid-silicate liquid crystal is used as a supramolecular template for a one-pot synthesis of the mater...

A first asymmetric total synthesis of (-)-isoschizogamine has been accomplished. Our synthesis features the facile construction of the carbon framework of the natural product through a Wagner-Meerwein rearrangement, a tandem metathesis, a stereoselective rhodium-mediated 1,4-addition of an arylboronic acid, and a ring-closing metathesis via a hemiaminal ether. PMID:22779733

Infusing leucine for 1 hr increases skeletal muscle protein synthesis in neonatal pigs, but this is not sustained for 2 h unless the leucine-induced fall in amino acids is prevented. We aimed to determine whether continuous leucine infusion can stimulate protein synthesis for a prolonged period whe...

An efficient total synthesis of flavans from the reactions of salicylaldehyde and acetophenone derivatives is reported. The synthesis involves preparation of chalcones through an aldol reaction followed by reduction of both the double bond and the ketone using NaBH4 and an acetic acid mediated cyclization. Methoxy groups on the aromatic rings did not affect significantly the yields of the procedure.

Recombinant acetyl xylan esterase (rAXE) of Aspergillus ficcum catalyzed the synthesis of peracetic acid (PAA) from ethyl acetate and hydrogen peroxide. Ten micrograms of rAXE catalyzed the synthesis of 1.34mM of PAA, which can be used for the pretreatment of cellulosic biomass in situ.

A review of recent developments in the synthesis and characterization of lubrication fluids and surfactants from methyl oleate. The synthesis of materials made using an epoxidation route is the focus. This versatile method of chemical modification of fatty acid methyl esters improves their oxidati...

Skeletal muscle grows at a very rapid rate in the neonatal pig, due in part to an enhanced sensitivity of protein synthesis to the postprandial rise in amino acids. An increase in leucine alone stimulates protein synthesis in skeletal muscle of the neonatal pig; however, the effect of isoleucine and...

Synthesis of the potent immunosuppressive agent, mycophenolate mofetil labelled with carbon-14 is described. Methoxyethoxymethyl (MEM) protected mycophenolate norbromide was prepared from unlabelled mycophenolic acid using a modified Hunsdiecker reaction. A three step synthesis furnished the title compound, having a specific activity of 53.8 mCi/mmol, in 49.5% overall yield from K{sup 14}CN. (author).

Abstract in english An experiment for the synthesis of isobutylene from tert-butanol dehydratation using oxalic acid as catalyst, followed by preparations of tert-butyl benzoate and tert-butyl cinnamate is described. The synthesis are simple, requiring two periods of 4 hours and are suitable for undergraduate organic chemistry experimental courses.

The disruption of the cutaneous permeability barrier results in metabolic events that ultimately restore barrier function. These include increased epidermal sterol, fatty acid, and sphingolipid synthesis, as well as increased epidermal DNA synthesis. Because tumor necrosis factor (TNF) and other cyt...

Synthesis of the epimer of pericosine B from (?)-quinic acid was achieved. This synthesis involves some regioselective and stereoselective processes. The desired product showed lower cytotoxic activity in comparison with natural pericosine B against the P388 leukemia cell line. The result implies that the stereocenter of C-6 in natural pericosine B plays an important role in this activity.   

Phosphatidates (PA or phosphatidic acid) were shown to have mitogenic properties, including the stimulation of DNA synthesis and calcium mobilization in C3H/10T1/2 cells. Their continuous presence for a minimum of 7 h induced DNA synthesis with kinetics similar to that observed when 10% fetal bovine...

A solvent-free synthesis of amides via the coupling of phosphazenes with carboxylic acids is reported. Increasing the rate of heating either by microwave irradiation or conventional heating results in multifold increase in the rate of amide bond formation. Synthesis of a library of amides including a potent antitumour candidate has been accomplished.

Enantioselective isoxazoline synthesis: A combination of 1) a catalytic enantioselective conjugate addition of oximes to alpha,beta-unsaturated aldehydes and 2) an acid-catalyzed intramolecular oxime-transfer reaction lead to the first asymmetric synthesis of 3-unsubstituted 2-isoxazolines (see scheme). PMID:19263445

This report presents information on (1) a new improved synthesis of carrier-free rhenium-188-labeled Re(V) dimercaptosuccinic acid (DMSA) complex as a potential therapeutic agent for treatment of thyroid medullary carcinoma; and (2) the synthesis and evaluation of a series of iodine-125-labeled analogues of altanserine for imaging of serotonin receptors.

The synthesis of trifluoromethyl diazirine with a stable isotope tag is reported. We found that both Friedel-Crafts acylation and reduction of aryl carbonyl to methylene, using commercially available stable-isotope reagents, were utilized for the synthesis of diazirinyl fatty acid derivatives. The stable isotope labeled diazirine may be valuable for identifying binding sites by mass spectrometry. PMID:15516771

Strains of Escherichia coli carrying mutations at the relA locus are deficient in cyclopropane fatty acid (CFA) synthesis, a phospholipid modification that occurs as cultures enter stationary phase. RelA protein catalyzes the synthesis of guanosine-3?,5?-bisdiphosphate (ppGpp); therefore, ppGpp was ...

The participation of global regulators GrrS (sensor kinase GacA/GacS-like regulatory system) and sigma S subunit of RNA polymerase in the control of phosphatase synthesis in a soil bacterium Serratia plymuthica was shown. In cells of null mutants for genes grrS and rpoS synthesis of acid and alkaline phosphatases was markedly decreased.

Phosphatidic acid phosphohydrolase (PAP), EC 3.1.3.4, is the penultimate step in the Kennedy pathway of triacyl glycerol (TAG) synthesis leading to the formation of diacyl glycerol (DAG), which is a key intermediate in TAG synthesis. We partially purified a soluble PAP from mid maturing seeds of bot...

This paper presents the synthesis of new polymer electrolyte membranes based on fluoropolymers incorporating aromatic perfluorovinyl ether sulfonic acids. A novel synthetic route describing the preparation of perfluorovinyl ether monomer containing sulfonic functionalities, 4-[(alpha,beta,beta-trifl...

In solid-phase oligodeoxyribonucleotide synthesis the addition of benzoic acid to internucleotide phosphodiester bond-forming reactions lowers coupling yields by far greater amount than anticipated on a simple nucleotide-carboxylate molar ratio. High coupling yields were consistently obtained in syn...

Here we report a simple procedure for generating colorimetric histone deacetylase (HDAC) substrates by solid-phase peptide synthesis based on racemization-free couplings of amino acid chlorides. We demonstrate the applicability of these substrates in HDAC assays. PMID:22902974

An efficient, simple, and environmentally clean synthesis of 3,4-dihydropyrimidinones in excellent yields in the presence of water without additional solvent/acid catalyst under conventional heating, microwave irradiation/ultrasound is reported.

... Return Samples, Properties of Nucleobases and Other Nitrogen Heterocycles ... Primordial synthesis of amines and amino acids in a 1958 Miller H2S-rich spark ... Isomer discrimination of polycyclic aromatic hydrocarbons in the Murchison ...

Primary alcohols were quantitatively oxidized in one-pot to acids via 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) mediated oxidation. The reported method is simple and suitable for large scale synthesis.   

New method for synthesis of adamantyl esters of acrylic, methacrylic, and cinnamic acids was developed. The reactions carried out under mild conditions in the absence of catalysts provide a high yield.

Stereoselective total synthesis of obolactone by the Bronsted acid (PTSA) mediated tandem cyclization of the appropriately substituted diketone in one-pot in a highly selective and efficient manner is reported.

A general approach for the quick synthesis of various 1,2,3-triazolo-?-lactams has been described, which involves the Huisgen [3 + 2] dipolar cycloaddition of azides derived from different amino acids with dimethyl acetylenedicarboxylate in water followed by cyclization.   

Mycophenolate mofetil (MMF), a prodrug of mycophenolic acid (MPA), is an inhibitor of inosine monophosphate dehydrogenase (IMPDH). It preferentially inhibits denovo pathway of guanosine nucleotide synthesis in T and B-lymphocytes and prevents their proliferation, thereby suppresses both cell mediate...

Abstract The first synthesis of enantiomerically pure 4,7-paracyclophane ditriflate starting from a quinone was reported. Using this molecule, mono- or dicoupling with boronic acids delivered enantiomerically pure arylparacyclophanes.

2. investigation of the association of nucleic acids and the protein synthetic machinery with .... (a) Diagram of a resting membrane illustrating the unit membrane concept; .... synthesis and function in nerve cell membranes and their derivatives.