Olivia Maya García

Unusual Oxidative Dealkylation of Certain 4-Alkyl-1,4-Dihydropyridines With MnO2/Bentonite Using Microwave Irradiation, in the Absence of Solvent (II)

Abstract Several Hantzsch 4-alkyl-1,4- dihydropyridines have been oxidized to the corresponding aromatic systems. An unexpected mixture of 4-alkyl pyridines and/or dealkylated pyridines are formed.

Oxydation d'esters de Hantzsch, par le nouveau système HNO3/bentonite, et irradiation aux micro-ondes

Resume We report the aromatization of 1,4-dihydropyridines on using system HNO3/Bentonite 1 in absence of solvent, by irradiation of the samples in a microwave oven, obtaining excellent yields on very short times comparing with the normal procedures.

MnO2/Bentonite: A New Reactive for the Oxidation of Hantzsch'S Dihydropyridines Using Microwave Irradiation, in the Absence of Solvent (I)

Abstract The oxidation of several 4-aryl-1,4-dihydrophyridines with MnO2 on Mexican Bentonite, without solvents, using as energy source a microwave over is described.

Migración y ruralización del SIDA: relatos de vulnerabilidad en comunidades indígenas de México

OBJETIVO: Analisar a vulnerabilidade ao IST/HIV entre mulheres indigenas mexicanas unidas em concubinato com homens que praticam sexo sem protecao. METODOS: Estudo etnografico realizado nos meses de fevereiro de 2004 e dezembro de 2005 nas localidades rurais de Michoacan e de Oaxaca, Mexico. Essas localidades possuem altos niveis de emigracao, pobreza e casos de HIV/Aids. Foram realizadas entrevistas em profundidade com 91 pessoas: migrantes sazonais (24), mulheres indigenas (33), autoridades locais (20) e profissionais de saude (14). RESULTADOS: A ruralizacao do HIV pode ser relacionada as praticas de iniciacao sexual femininas e sobretudo ao medo do migrante de que sua esposa tenha relacoes extra-conjugais em sua ausencia. A gravidez e a crianca sao recursos masculinos para controlar suas esposas. CONCLUSOES: A migracao de retorno implica formas de vulnerabilidade para as mulheres indigenas nas localidades estudadas, cuja sexualidade tem carater marcadamente reprodutivo. E necessario desenvolver politicas de prevencao a IST/HIV dirigidas ao fortalecimento dos direitos sexuais reprodutivos das mulheres e que considerem aspectos da identidade masculina.

A Direct Synthesis of Aromatic Nitriles from Aldehydes Using a Mexican Bentonite and Microwave or Infrared Irradiation, in Absence of Solvent

Abstract An efficient and simple procedure for the direct conversion of aromatic Aldehydes into the corresponding nitriles with hydroxylamine hydrochloride and a Mexican Bentonite via infrared or microwave irradiation.

Synthesis of 1,3,5-trioxanes : a new, simple method using a bentonitic earth as catalyst

Abstract A simple method for synthesizing aliphatic as well as aromatic 1,3,5-trioxanes using as catalyst a bentonitic earth is reported. The yields ranged from good to excellent.

Oxydation d'alcools benzyliques et allyliques par le système MnO2/bentonite sous irradiation aux micro-ondes ou ultrasons en absence de advant.

Abstract A new selective and simple method for benzylic and allylic alcohols oxidation to aldehydes is reported. The oxidation is achieved with MnO 2 /bentonite bd1 /microwave and MnO 2 / bentonite/ultrasound, both in dry medium.

A NEW STRATEGY FOR THE SYNTHESIS OF N-SUBSTITUTED 2,5-DIMETHYLPYRROLES IN HETEROGENEOUS MEDIUM.

A novel preparation in dry medium of N-substituted 2,5-dimethylpyrroles using a clay as catalyst and infrared energy is described. Introduction. It is well know that the Paal-Knorr reaction is the most general synthetic method to prepare furan, pyrrole and thiophene derivatives (1). This method consists in the reaction of a 1,4-dicarbonyl compound with a dehydrating acid, or ammonia, primary amines, hydroxylamine, hydrazines or an inorganic sulfur salt, respectively. An interesting application of this method is the protection of a primary amine group against attack by strong bases or nucleophiles by incorporation into an N-substituted 2,5-dimethylpyrrole system from which the amine group is regenerated by treatment with hydroxylamine hydrochloride (2). In previous papers, we described the use of a natural clay as acid catalyst in different organic reactions (3-6). We present in this report the results obtained for the reaction of primary amines with acetonylacetone using infrared radiation and a natural clay as catalyst in absence of solvent, as a variation to the Paal-Knorr reaction. Results and Discussion. Several N-substituted 2,5-dimethylpyrroles were obtained by the proposed method (Table 1). Because of the short reaction times and the high yield of the obtained products, we believe that this new method can be considered as a simple, efficient and good alternative general route to generate the titled compounds. We observed that when the reactions were repeated following the general procedure without the use of the clay, in the majority of the cases the reaction product was not formed, and only in the case of p-methylaniline and benzylamine was the pyrrole derivative formed and in low yield (minor to 20%) and with longer reaction times (more than 30 minutes). Then, the catalyst provides more desireable conditions to this modification for the Paal-Knorr reaction. Furthermore, we hope that this method can be implemented to synthesize homologue structures with other heteroatoms. Vol. 4, No. 1, 1998 A New Strategy For The Synthesis of N-substituted, 2,5 Dimethylpyrroles in Heterogenous Medium Table 1. Synthesis of N-Substituted 2,5-Dimethylpyrroles

COMPARATIVE STUDY OF ε-CAPROLACTAM SYNTHESIS USING DIFFERENT ENERGY SOURCES AND A NATURAL CLAY AS CATALYST

We report a new method for the production of ε-caprolactam from cyclohexanone and NH2OH.HCI using different sources of energy in presence of a Mexican clay in dry medium. Introduction. One of the classical reactions in organic chemistry is the Beckmann rearrangement (1). An important industrial application of this process is in the synthesis of ε-caprolactam, which is the raw material for obtaining Nylon 6. Recently, this lactam has been prepared by the Beckmann reaction of cyclohexanone oxime and using a zeolite as catalyst (2), or by refluxing a suspension of 6-aminocaproic acid previously supported in zeolite, silica gel or alumina (3). We have reported previously the use of a natural clay as acid catalyst in several organic reactions, such as the regeneration of carbonyl compounds from their oxime derivatives (4,5). In the case of p-hydroxy and p-methoxy acetophenone oximes; the carbonyl compound was not regenerated, but the corresponding amides were obtained through the Beckmann rearrangement. This observation and the fact that oximes can be prepared in dry medium (6), led us to consider the transformation reaction of aromatic aldehydes into the corresponding nitriles in a one step reaction. Also in this case the Beckmann rearrangement was observed. We present here, the results of a comparative study for the synthesis of εcaprolactaim when cyclohexanone and NH2OHOHCI are irradiated with infrared, ultrasound, microwave or heat as energy sources using a natural clay (Table 1). Results and Discussion. Table 1 shows that when weak bases, such as Na2C03 or NaHC03 are used, the yield of ε-caprolactam increases in all but one case (ultrasound). The best conversion (92%) was obtained with infrared radiation. Although the acid character of the natural clay satisfy the conditions required for the Beckmann rearrangement, in earlier experiments using more acidic conditions, we found that the caprolactam yield was near zero with microwave energy. Therefore, we decided to add weak basic compounds to the reaction mixture and found surprisingly that the yields increased dramatically when infrared or microwave radiation was used. We suggest, in accord with Sato and coworkers (2), that the active site in the catalyst is a neutral moiety; hence, the role of base is thought to be to neutralize the hydroxyl amine hydrochloride so the free hydroxyl amine could undergo nucleophillic attack on the cyclohexanone. We propose that the oxime is formed as an intermediate and it can give the Beckmann rearrangement or carbonyl compound regeneration. This behavior is clearly observed when infrared, microwave and thermal energy were used. However, when ultrasound energy was used, the oxime was one of the main reaction products.

Migration and ruralization of AIDS: reports on vulnerability of indigenous communities in Mexico

OBJETIVO: Analisar a vulnerabilidade ao IST/HIV entre mulheres indigenas mexicanas unidas em concubinato com homens que praticam sexo sem protecao. METODOS: Estudo etnografico realizado nos meses de fevereiro de 2004 e dezembro de 2005 nas localidades rurais de Michoacan e de Oaxaca, Mexico. Essas localidades possuem altos niveis de emigracao, pobreza e casos de HIV/Aids. Foram realizadas entrevistas em profundidade com 91 pessoas: migrantes sazonais (24), mulheres indigenas (33), autoridades locais (20) e profissionais de saude (14). RESULTADOS: A ruralizacao do HIV pode ser relacionada as praticas de iniciacao sexual femininas e sobretudo ao medo do migrante de que sua esposa tenha relacoes extra-conjugais em sua ausencia. A gravidez e a crianca sao recursos masculinos para controlar suas esposas. CONCLUSOES: A migracao de retorno implica formas de vulnerabilidade para as mulheres indigenas nas localidades estudadas, cuja sexualidade tem carater marcadamente reprodutivo. E necessario desenvolver politicas de prevencao a IST/HIV dirigidas ao fortalecimento dos direitos sexuais reprodutivos das mulheres e que considerem aspectos da identidade masculina.