Carbonylation of olefins by carbon monoxide and alcohols in the presence of Pd-complex catalytic system

In order to develop new, efficient and environmentally friendly methods for the preparation of practically valuable esters of carboxylic acids, studies of the hydroalkoxycarbonylation reaction of a number of terminal olefins of normal structure (hexene-1, heptene-1, octene-1, nonene-1) with carbon monoxide and alcohols in presence of metal complex catalysts based on palladium phosphine complexes at low carbon monoxide pressures (≤ 20 atm).Two-and three-component systems based on PdCl2 and Pd(Acac)2, PdCl2(PPh3)2, Pd(PPh3)4 complexes containing a free ligand (PPh3) as a stabilizer and Bronsted acid (TsOH) as a promoter were studied as catalysts. It was shown that only the three-component systems PdCl2-PPh3-TsOH, PdCl2(PPh3)2-PPh3-TsOH, Pd(Acac)2-PPh3-TsOH, and Pd(PPh3)2-PPh3-TsOH have the highest catalytic activity in the studied reactions. It was found that the reaction of hydroalkoxycarbonylation of α-olefins proceeds with the formation of a mixture of linear and branched products. The influence of various conditions of the reaction (the ratio of the initial reagents and the components of the catalytic systems, temperature, CO pressure, duration) on the course of the process and on the yield of the target products was investigated. The optimal parameters of the studied reactions have been found.

High-Performance Liquid Crystalline Polyesters: Influence of the Synthetic Pathway on the Thermal Properties

Liquid crystalline (LC) copolyesters derived from 4-hydroxybenzoic acid, terephthalic acid, and bisphenol A were synthesized under a variety of reaction conditions. Carboxylic groups in the raw materials were involved in either direct polycondensation or transesterification reactions. Protecting the carboxylic groups via methyl ester or phenyl ester formation was found to increase the yield and the molecular weight of the samples. It turned out that the maximal value of the degree of polymerization and, consequently, the highest heat resistance was observed for the samples prepared using phenyl esters of carboxylic acids.

On the possibility of evaluative prediction of the extraction of organic substances of complex structure using the method of group increments

The distribution of pesticides of different classes (amides, anilinopyrimidines, benzene derivatives, benzoylphenylureas, benzenesulfonates, hydrazides, dinitroanilines, carbamates, pyretroids, pyrimidines, tetrazines, triazoles, pheny lureas, organophosphorus compounds, esters of carboxylic acids) was studied at 20 ± 1 °C in the extraction systems of hexane–water, hexane–acetonitrile, hexane– acetonitrile and water mixture that are most often used in analytical chemistry of pesticides. The distribution constants P of pesticides and the increments of logarithms of the distribution constants If of their functional groups between the hydrocarbon and polar phases are calculated. Two main methods for evaluative prediction of lg P of pesticides are proposed and approved – substitutive method based on the calculation of lg P by replacing the substituents in the base molecule and the method of absolute addition of increments. The possibilities of the both methods are illustrated. The reasons for the deviations of the experimental values from the calculated ones are discussed. The influence of the nature and composition of the polar phase on the magnitudes of the observed deviations is estimated. In particular, they decrease dramatically with an increase in the acetonitrile content in the polar phase. Averaged values of correction to the calculated values of lg P are introduced. In most cases, they allow predicting lg P of pesticides with a deviation of not more than 0.5–1.0 from the calculated one.

Cu-Photoredox-catalyzed C(sp)–C(sp3) coupling of redox-active esters with terminal alkynes

Under mild condition, redox-active esters of carboxylic acids reacted with aryl and alkyl substituted alkynes in good yields. A copper-acetylid-ligand is a key intermediate for constructing C(sp)–C(sp3) bond.