Journal of the Brazilian Chemical Society 

About: Journal of the Brazilian Chemical Society is an academic journal published by Brazilian Chemical Society. The journal publishes majorly in the area(s): Catalysis & Chemistry. It has an ISSN identifier of 0103-5053. It is also open access. Over the lifetime, 5698 publications have been published receiving 84615 citations. The journal is also known as: Brazilian Chemical Society Journal & J. Braz. Chem. Soc..

Transesterification of vegetable oils: a review

Abstract: The transesterification of vegetable oils with methanol as well as the main uses of the fatty acid methyl esters are reviewed. The general aspects of this process and the applicability of different types of catalysts (acids, alkaline metal hydroxides, alkoxides and carbonates, enzymes and non-ionic bases, such as amines, amidines, guanidines and triamino(imino)phosphoranes) are described. Special attention is given to guanidines, which can be easily heterogenized on organic polymers. However, the anchored catalysts show leaching problems. New strategies to obtain non-leaching guanidine-containing catalysts are proposed. Finally, several applications of fatty acid esters, obtained by transesterification of vegetable oils, are described.

On the solid, liquid and solution structural organization of imidazolium ionic liquids

Abstract: Sais derivados do cation 1,3-dialquilimidazolio sao uma das mais populares e investigadas classes de liquidos ionicos a temperatura ambiente. Embora, em varios casos, suas propriedades fisico-quimicas e/ou o resultado dos processos que ocorrem nesses liquidos diferem significantemente daqueles obtidos em solventes orgânicos dipolares, estes ainda podem ser descritos como simples solventes orgânicos. Nesta revisao, sera introduzido o conceito que liquidos ionicos derivados do cation 1,3-dialquilimidazolio sao mais convenientemente descritos como estruturas polimericas supramoleculares do tipo {[(DAI) x (X) x-n )] n+ [(DAI) x-n (X) x )] n} n onde DAI representa o cation 1,3dialquilimidazolio e X o ânion. Este padrao estrutural e observado geralmente em solidos e mantido em grande extensao no estado liquido e mesmo em fase gasosa. A introducao de outras moleculas ou macromoleculas no liquido ionico provoca a perturbacao da rede de ligacoes de hidrogenios podendo gerar, em alguns casos, nano-estruturas com regioes polares e apolares onde compostos de inclusao podem ser formados. 1,3-dialkyl imidazolium salts are one of the most popular and investigated classes of room temperature ionic liquids. Although in various cases the physical-chemical properties and/or the outcome of the processes in these liquids significantly differ from those performed in “classical” dipolar organic solvents, they are still regarded as merely homogeneous solvents. In this brief overview it is developed the concept that pure 1,3-dialkylimidazolium ionic liquids are better described as hydrogen-bonded polymeric supramolecules of the type {[(DAI) x (X) x-n )] n+ [(DAI) x-n (X) x )] n} n where DAI is the 1,3-dialkylimidazolium cation and X the anion. This structural pattern is a general trend for the solid phase and is maintained to a great extent in the liquid phase and even in the gas phase. The introduction of other molecules and macromolecules occurs with a disruption of the hydrogen bond network and in some cases can generate nano-structures with polar and non-polar regions where inclusion-type compounds can be formed.

The chemistry of isatins: a review from 1975 to 1999

Abstract: Isatins (1H-indole-2,3-dione) are synthetically versatile substrates, where they can be used for the synthesis of a large variety of heterocyclic compounds, such as indoles and quinolines, and as raw material for drug synthesis. Isatins have also been found in mammalian tissue and their function as a modulator of biochemical processes has been the subject of several discussions. The advances in the use of isatins for organic synthesis during the last twenty-five years, as well as a survey of its biological and pharmacological properties are reported in this review and in the accompanying supplementary information.

Biodiesel: an overview

Abstract: The importance of biodiesel production was analyzed based on scientific articles and patents. A critical analysis was presented on the most used oil sources, the catalysts and the methods to verify the transesterification yields. Also analyzed were the comparative studies on emissions from pure fossil diesel and mixtures with biodiesel in variable proportions. Finally some challenges and considerations focused on technological, agronomic and infrastructure aspects of biodiesel production were indicated.

Near Infrared Spectroscopy: fundamentals, practical aspects and analytical applications

Abstract: This paper intends to review the basic theory of Near Infrared (NIR) Spectroscopy and its applications in the field of Analytical Science. It is addressed to the reader who does not have a profound knowledge of vibrational spectroscopy but wants to be introduced to the analytical potentialities of this fascinating technique and, at same time, be conscious of its limitations. Essential theory background, an outline of modern instrument design, practical aspects, and applications in a number of different fields are presented. This work does not intend to supply an intensive bibliography but refers to the most recent, significant and representative material found in the technical literature. Because this paper has been produced as consequence of the First Workshop on Near Infrared Spectroscopy, whose venue was Campinas - Brazil, as a pre-conference activity of the XI National Meeting on Analytical Chemistry (ENQA), it also depicts the state of the art of NIR spectroscopy in Brazil, pointing out the current achievements and the need to take the technology to a level consistent with this country's economical activities.