Revista Boliviana de Química

Polyolefins production in Bolivia; part I: investigation of markets, technologies and catalytic processes (a review)

The polyethylene market status was evaluated globally, and especially in South America, identifying the role of Bolivia, in its way from importer to exporter, on the basis of the polymers plant projected for 2018. The source and the characteristics of the prime matter were identified, as well as the technology and the type of products. Also, the diverse technologies of polymerization for the products: HDPE, LLDPE, LDPE, etc., are discussed in this review. Simulation of the ethylene polymerization in a fluidized bed reactor is here discussed

Análisis de 'subspace clustering' de moléculas utilizando Chameleoclust, un algoritmo evolutivo

'Subspace clustering' has been successfully applied to different datasets, especially those characterized by a high dimensionality. However most of the traditional state-of-the-art 'subspace clustering' algorithms have usually many parameters that are hard to tune. Recently, it has been proposed a new evolutionary 'subspace clustering' that takes advantage of its evolvable genome structure to adapt to different datasets without any complicated parameters tuning. In this paper we apply this new technique to study 36 chemical molecules characterized by a large number of molecular descriptors in order to determine clusters with distinctive characteristics likely to be adsorbed on activated carbon BPL.

La técnica de minería de datos conocida como 'subspace clustering' ha sido aplicada exitosamente a diversos tipos de datos, especialmente a datos caracterizados por un gran número de dimensiones. Sin embargo muchos de los algoritmos de 'subspace clustering' clásicos poseen un gran número de parámetros y son difíciles de calibrar. Recientemente, fue propuesto un algoritmo evolutivo de 'subspace clustering', capaz de adaptar su genoma para lidiar con distintos datos sin necesidad de calibrar los parámetros. En este artículo aplicamos esta nueva técnica al estudio de 36 moléculas químicas caracterizadas por un gran número de descriptores moleculares con el fin de determinar clusters de moléculas con características peculiares, susceptibles a ser adsorbidos sobre carbón activado BPL

Stereospecific synthesis of alkenes from 1,2-diols; mechanistic views: the organic chemistry notebook series, a didactical approach, N ° 8

This is the eighth chapter in the series: "The Organic Chemistry Notebook Series, a Didactical Approach". The aim of this series of studies is to help students to have a graphical view of organic synthesis reactions of diverse nature. Here we discuss, from a mechanistic stand point, some methods for the stereospecific synthesis of alkenes from 1,2-diols. One of the best ones utilizes as precursors, the cyclic thionocarbonates obtained from the diol with thiophosgene. We describe by mechanisms, the use of 1,3-dimethyl-2-phenyl-1,3,2-diazophospholidine as an alternative for the decomposition of thionocarbonates into alkenes. We discuss by mechanisms, a general and unambiguous method for the interconversion of Z- and E-alkenes. Thus, the conversion of the (Z)-cyclooctene into the E isomer is detailed here. The mechanism of the conversion of meso-1,4-diphenylbutan-2,3-diol into (Z)-1,4-diphenyl-2-butene is here described. We have used various series of reactions reviewed by W. Carruthers in 'Some modern methods of organic synthesis', and we have proposed didactical and mechanistic views for them. This theme is included in the chapter "Formation of carbon-carbon double bonds" in the text mentioned above.