Revista Boliviana de Química

Synthesis of Alkenes by oxidative decarboxylation of carboxylic acids: mechanistic views; the organic chemistry notebook series, a didactical approach, N° 6

This is the sixth chapter in the series published by the same authors: "The Organic Chemistry Notebook Series, a Didactical Approach". Here we offer the mechanistic views of the synthesis of alkenes by oxidative decarboxylation of carboxylic acids. The aim of this series of studies is to help students to have a graphical view of organic synthesis reactions of diverse nature. The oxidative decarboxylation of carboxylic acids is a useful method for generating alkenes. Here we propose the mechanism and its discussion for the application of the method of decarboxylation of diacids lacking nearby double bonds. Also, the route is explained mechanistically for the preparation of Dewar benzene. The thermal or photolytic decomposition of di-t-butyl per-esters is described. The treatment of monocarboxylic acids to afford alkenes in the presence of lead tetraacetate and copperII acetate is briefly discussed. The alkylation-decarboxylation of aromatic acids is also explained. The oxidative decarboxylation of carboxylic acids can eventually conduct to the obtaining of ketones instead of alkenes. We have used a series of reactions reviewed by W. Carruthers, and we have proposed didactical and mechanistic views for them. This latest approach is included in the synthetic methods reviewed by W. Carruthers with respect to the "Formation of carbon-carbon double bonds". Spanish title: Síntesis de alquenos por descarboxilación de ácidos carboxílicos; vistas mecanísticas; De la serie: El cuaderno de notas de química orgánica, un enfoque didáctico, N°6.

Synthesis of the anti-cancer carboplatin oxidized, and study of its interactions with n-bases by cyclic voltammetry

The anticancer drug cis-diammine-(1,1-cyclobutanedicarboxylate)-trans-dihydroxyplatinum (IV) or carboplatin-oxidized was synthesized with 98% purity by oxidizing the carboplatin Pt (II) with hydrogen peroxide 30%. The elemental analysis was confirmed by Atlantic Microlab Inc. Company (Norcross-Georgia, USA). The study of the electrochemical behavior of CBDCAOX interacting with nitrogenous bases was performed in a range of -200 mV to -700 mV with a voltammetric analyzer BAS 50W model. The free CBDCAOX voltammogram showed a reduction signal in -625.4 mV and during the interaction with thymine the signal shifted to less negative potentials. This result indicates the formation of a strong bond in CBDCAOX-thymine complex. Spanish title: Síntesis del anticanceroso carboplatino oxidado y estudios electroquímicos de sus interacciones con bases nitrogenadas por voltametría cíclica.

El fármaco anticanceroso cis-diamino-(1,1-ciclobutanodicarboxilato)-trans-dihidroxiplatino (IV) o carboplatino-oxidado se sintetizó con 98% de pureza, oxidando el carboplatino Pt(II) con peróxido de hidrógeno al 30%. El análisis elemental fue confirmado por la compañía Atlantic Microlab, Inc. (Norcross-Georgia, USA). El estudio del comportamiento electroquímico del CBDCAOX interaccionando con bases nitrogenadas se realizó en un rango de -200 mV a -700 mV con un analizador voltamétrico modelo BAS 50W. El voltamograma de CBDCAOX libre mostró una señal de reducción en -625.4 mV y al interaccionar con timina la señal se desplazó hacia potenciales menos negativos. Este resultado indica la formación de un enlace fuerte en el complejo CBDCA-OX-timina.

Kinetics of chromium(III) uptake by nostoc sp. algae

An alga arising from Lake Titicaca basin (Bolivia, South America), has been studied faced with adsorption kinetics of Cr(III). The samples of Nostoc sp. were put in contact with chromium (III) solutions at 18°C. The pH effect has been measured from 2.50 up to 5.40. Concentration-time profiles shown exponential functions or first order processes. There is a linear relationship between pH and rate constants k o from 8.0x10-3 min-1 to 8.3x10-2 min-¹. At low pH, metal adsorption is negligible and maximum at high pH. Different initial concentrations of Cr(III), yielded also first order rate constants between 2.9x10-²min-¹ and 5.0x10-3min-1. Hydrogen ions would be competing against metal ions in order to achieve active sites. As possible mechanisms, not only the ion exchange could be involved, but also complex