Sample records for lewis acids
from WorldWideScience.org

Sample records 1 - 4 shown.



1

Síntese de 1-indanonas através da reação de acilação de Friedel-Crafts intramolecular utilizando NbCl5 como ácido de Lewis/ Synthesis of 1-indanones through the intramolecular Friedel-Crafts acylation reaction using NbCl5 as Lewis acid

Polo, Ellen Christine; Silva-Filho, Luiz Carlos da; Silva, Gil Valdo José da; Constantino, Mauricio Gomes
2008-01-01

Resumo em inglês The intramolecular Friedel-Crafts acylation reaction of 3-arylpropanoic acids to give 1-indanones can be effected in good yields under mild conditions (room temperature) by using niobium pentachloride. Our results indicate that NbCl5 acts both as reagent (to transform carboxylic acids into acyl chlorides) and as catalyst in the Friedel-Crafts cyclization.

Scientific Electronic Library Online (Portuguese)

2

Estudo comparativo duplamente encoberto entre Sevoflurano Genérico e Sevorane®/ A double-blind comparative study between generic Sevoflurane and SevoraneTM/ Estudio comparativo doblemente encubierto entre Sevoflurano genérico y Sevorane®

Portella, Alfredo Augusto Vieira; Laurencel, Solange Maria; Rosa, Deise Martins; Rivera, Maria Isabel Moscote; Quintero, Santiago Osorno
2010-10-01

Resumo em português JUSTIFICATIVA E OBJETIVOS: O sevoflurano é acondicionado em três tipos de recipientes. As diferenças de propriedades físico-químicas desses produtos se devem aos diversos processos de fabricação, embora sejam essencialmente idênticos quanto às provas de comparação química. Existe a hipótese de que a molécula do sevoflurano possa apresentar instabilidade química devido à formação de ácidos de Lewis em conse quência do material utilizado para a fabricaç (mais) ão dos frascos e do teor de água. O objetivo deste trabalho foi analisar a eficácia clínica do sevoflurano quando acondicionado em frascos diferentes. MÉTODO: Foram estudados 64 pacientes adultos distribuídos aleatoriamente em dois grupos. Foram utilizados dois vaporizadores Datex-Ohmeda, sendo um abastecido apenas com Sevoflurano Genérico e o outro com Sevorane®. O coordenador do estudo foi o responsável pelo abastecimento dos vaporizadores e não realizou nenhuma anestesia. Em ambos os grupos, utilizou-se a mesma técnica anestésica e a mesma monitoração (ECG, FC, SpO2, P ET CO2, BIS, SEF, TOF, % INSP, % EXP, PAS, PAD). RESULTADOS: Durante a anestesia não houve diferença entre os grupos. Houve diferença estatística entre a interrupção do sevoflurano e a abertura espontânea dos olhos (13,91 ± 6,39 min Grupo II, e 10,34 ± 6,05 min Grupo I) e a interrupção do sevoflurano e o aperto de mão ao comando verbal (15,38 ± 6,47 min Grupo II, e 11,88 ± 6,60 min Grupo I). Não houve diferença estatística entre a interrupção do sevoflurano e o momento em que os pacientes atingiram Índice de Aldrete-Kroulik igual ou superior a 8. CONCLUSÕES: Durante a anestesia, não houve diferença entre os grupos. Embora o despertar tenha sido 3,5 minutos mais rápido no Grupo I (Sevoflurano Genérico), os anestesiologistas não observaram qualquer diferença no comportamento clínico dos pacientes quanto a esse aspecto Resumo em espanhol JUSTIFICATIVA Y OBJETIVOS: El Sevoflurano se coloca en tres tipos de recipientes. Las diferencias de propiedades físico-químicas de esos productos se deben a los diversos procesos de fabricación, aunque sean esencialmente idénticos en cuanto a las pruebas de comparación química. Existe la hipótesis de que la molécula del Sevoflurano pueda presentar una inestabilidad química debido a la formación de ácidos Lewis, como consecuencia del material utilizado para la (mais) fabricación de los pomos y del contenido de agua. El objetivo de este trabajo fue analizar la eficacia clínica del Sevoflurano cuando fue acondicionado en pomos diferentes. MÉTODO: Se estudiaron 64 pacientes adultos distribuidos aleatoriamente en dos grupos. Fueron utilizados dos vaporizadores Datex-Ohmeda, siendo uno de ellos abastecido apenas con Sevoflurano Genérico y el otro con Sevorane®. El coordinador del estudio fue el responsable por el abastecimiento de los vaporizadores y no realizó la anestesia. En los dos grupos, se usó la misma técnica anestésica y la misma monitorización (ECG, FC, SpO2, P ET CO2, BIS, SEF, TOF, % INSP, % EXP, PAS, PAD). RESULTADOS: No hubo diferencia entre los grupos durante la anestesia. Pero sí que hubo una diferencia estadística entre la interrupción del Sevoflurano y la abertura espontánea de los ojos (13,91 ± 6,39 min Grupo II, y 10,34 ± 6,05 min Grupo I), y la interrupción del Sevoflurano y el apretón de la mano al comando verbal (15,38 ± 6,47 min Grupo II, y 11,88 ± 6,60 min Grupo I). No hubo diferencia estadística entre la interrupción del Sevoflurano y el momento en que los pacientes alcanzaron el Índice de Aldrete-Kroulik igual o superior a 8. CONCLUSIONES: Durante la anestesia, no se registró diferencia entre los grupos. Aunque el despertar haya sido 3,5 minutos más rápido en el Grupo I (Sevoflurano Genérico), los anestesistas no se percataron de ninguna diferencia en el comportamiento clínico de los pacientes en cuanto a ese aspecto Resumo em inglês BACKGROUND AND OBJECTIVES: Sevoflurane is presented in three types of vials. The differences in physical-chemical properties of those products are due to different manufacturing processes, although they are essentially identical regarding chemical comparison tests. It has been hypothesized that the Sevoflurane molecule could present chemical instability due to the formation of Lewis acids as a consequence of the materials used in the fabrication of the vials and the water (mais) content. The objective of this study was to analyze the clinical efficacy of Sevoflurane conditioned in different vials. METHODS: Sixty-four adult patients were randomly divided into two groups. Two Datex-Ohmeda vaporizers, one with only Generic Sevoflurane and the other with SevoraneTM, were used. The study coordinator was responsible for supplying the vaporizers and he did not participated in none anesthetic procedures. The same anesthetic technique and monitoring (ECG, HR, SpO2, P ET CO2, BIS, SEF, TOF, % INSP, % EXP, SBP, and DBP) were used in both groups. RESULTS: During anesthesia, differences were not observed between both groups. A statistically significant difference was observed in the time between the interruption of Sevoflurane and spontaneous eye opening (13,91 ± 6.39 min in Group II, and 10.34 ± 6.05 min in Group I) and the interruption of Sevoflurane and handgrip on verbal command (15.38 ± 6.47 min in Group II, and 11.88 ± 6.60 in Group I). A statistically significance difference was not observed between the interruption of Sevoflurane and the moment that patients achieved an Aldrete- Kroulik index equal or above 8. CONCLUSIONS: during anesthesia a significant difference between both groups was not observed. Although awakening was 3,5 minutes faster in Group I (Generic Sevoflurane), anesthesiologists did not observe any difference in the clinical behavior of patients

Scientific Electronic Library Online (Portuguese)

3

Reações de Etanol com CO/H2 na Presença do Sistema Catalítico Ru(acac)3/I-/ Ethanol, reactions with co/h2 in the presence of the ru(acac)3/i- catalytic system

Trabuco, Elizeu
1997-06-01

Resumo em inglês The hydrocarbonylation reaction of ethanol with a CO/H2 mixture assisted by Ru(acac)3/iodide was investigated. Bronsted and Lewis acids and iodides salt were used as homogeneous promoters. The etherification reaction was the main reaction under typical acidic conditions of the catalytic system. When a hydrocarbon solvent (toluene) was added to the initial reaction, the alcohol conversion and the carbonylation products were increased. The catalytic activity of the Bronsted (mais) acids (conv. EtOH = 71-92%) was higher than that of the Lewis acids promoters (conv. EtOH = 65-85%). The salt present the lower catalytic activity among the promoters used. The long time reaction carried out with ethanol showed an increase of the product selectivity of the homologation and carbonylation reactions while the etherification reaction selectivity decreased. The recycled ether led to 60-65% ethanol conversion to C5 and C6 products. The main catalytic species are H+[Ru(CO)3I3]-, [HRu3(CO)11]- and [HRu(CO)4]-. The first one is active in the carbonylation and homologation reactions of alcohols while the two others take part only in the homologation reaction.

Scientific Electronic Library Online (Portuguese)

4

Alilação e crotilação catalítica e enantiosseletiva de aldeídos/ Enantioselective catalytic allylation and crotylation of aldehydes

Fátima, Ângelo de; Robello, Luís Gustavo; Pilli, Ronaldo Aloise
2006-10-01

Resumo em inglês The field of chiral catalysis has experienced explosive growth over the last two decades. By now, many of the classical reactions in organic synthesis can be carried out efficiently in asymmetric manner. As one of the fundamental and powerful C-C bond-forming reactions, enantioselective catalytic allylation (ECA) and crotylation (ECC) of aldehydes has attracted considerable attention. In this article, we present an overview about the importance of chiral Lewis acids and b (mais) ases in catalytic enantioselective addition of allyl- and crotyl metals to aldehydes and the application of this methodology in the total synthesis of natural and non-natural products.

Scientific Electronic Library Online (Portuguese)