COHERENT SYNCHRONIZATION OF PYRIDINE DIMERIZATION REACTIONS AND DECOMPOSITION OF “GREEN OXIDANTS” – H2O2 AND N2O

In recent years, hydrogen peroxide and nitrous oxide (1) "green oxidants" – have attracted much attention of researchers as a selective oxidizing agent for the catalytic oxidation of pyridine bases. In this regard, the reaction of pyridine oxidation by hydrogen peroxide and nitrous oxide under homogeneous conditions, in the gas phase, without the use of catalysts, at atmospheric pressure, has been experimentally investigated. Areas of selective oxidation of pyridine with hydrogen peroxide and nitrous oxide have been established, and optimal conditions have been found for obtaining valuable raw materials required in the petrochemical, chemical, and pharmaceutical industries

HETEROGENEOUS CATALYTIC CONVERSIONS OF ACETYLENE

The reactions of interaction of acetylene with water vapor, acetic acid and ammonia in the presence of heterogeneous catalysts have investigated. Depending on the nature of the starting components used, acetaldehyde and acetone, vinyl acetate, pyridine bases and pyrrole synthesized. Heterogeneous catalysts selected for each studied reaction based on some scientific prerequisites for the selection of catalysts. Active catalysts for the investigated reactions were determined, which contain compounds of cadmium, zinc, bismuth, chromium, iron and copper, in general, d-group metals. γ-Al2O3, bentonite and kaolin used as a catalyst carrier. Hydrofluoric acid, acetic acid, ammonium fluoride and others used for peptization. Some hypothetical mechanisms for the formation of target products for each reaction have proposed.

CATALYTIC SYN TIC SYNTHESIS OF PYRIDINES BASED ON THE CRO THESIS OF PYRIDINES BASED ON THE CROTON FRACTION

Background. The presence in the molecule of pyridine bases of nitrogen atoms having the properties of the bases determines the specificity of the products of this class and gives ample opportunities for their use in various industries. . The chemistry of pyridine bases is associated with such general theoretical issues as the electronic structure of the cycle, aromaticity, the effect of substituents on the reactivity of heterocycles in nucleophilic substitution reactions, and tautomerism. At the same time, systematic data on the reactions of alkylation with dihalo-alkanes, acylation under low-temperature poly-condensation, and complexation were not available to create a complete picture of the reactivity of pyridine bases. Materials and methods. The aim of the work is to develop cheap and convenient methods for the preparation of pyridine bases, to search for effective and selective process catalysts, and to determine the degree of anticorrosion protection of metals of the obtained products.

PROMOTING EFFECT OF PYRIDINE BASES ON INDIRECT ELECTROCHEMICAL OXIDATION OF ALCOHOLS

The effect of pyridine on the reaction of indirect electrochemical oxidation of alcohols to carbonyl compounds by the catalytic system of 4-acetylamino-2,2,6,6-tetramethylpiperidine-1-oxyl - iodine in a two-phase aqueous-organic medium: methylene chloride - an aqueous solution of sodium bicarbonate (pH 8.6) was studed. It was shown that the process of indirect electrochemical oxidation of alcohols is accelerated by 1.5–2 times in the presence of pyridine. The corresponding aldehydes and ketones are formed with a high yield (75-95%) after passing 2-2.2 F of electricity. Additionally, the effect of other pyridine bases (2,6-lutidine, 4-acetylpyridine, 2-methyl-5-ethylpyridine, collidine) on indirect electrochemical oxidation of alcohols was studied using the example of 1-octanol. The absence of significant differences in the promoting action of pyridine bases was established and it was shown that in all cases the octanol is obtained with a high yield and coulombic efficiency (90-95 %). A mechanism for the reaction of indirect electrochemical oxidation of alcohols with the participation of 4-acetylamino-2,2,6,6-tetramethylpiperidine-1-oxyl and pyridine bases is proposed. The promoting effect of pyridine (or other pyridine bases) consists in the formation of an intermediate complex between the base, oxoammonium cation and alcohol. The formation of the complex facilitates the rapid transfer of the proton from the alcohol to the pyridine base and the hydride ion to the oxoammonium cation with the formation of the corresponding carbonyl compound from the alcohol. The preparative methods for the electrochemical synthesis of carbonyl compounds from aliphatic, cyclic, aromatic, heterocyclic alcohols including synthesis of 2,5-diformylfuran from 5-hydroxymethylfurfuralin using the two-phases catalytic system of 4-acetylamino-2,2,6,6-tetramethylpiperidine-1-oxyl - potassium iodide in the presence of pyridine bases, are proposed.

Effect of Si/Al Ratios on the Structure and Catalytic Properties of Alkaline-Treated ZSM-5 Catalysts

A series of hierarchical HZSM-5 catalysts were synthesized by alkaline (denoted as HZSM-5-At) and/or alkaline-acid (denoted as HZSM-5-At-acid) treatments, and they as catalyst pairs were employed for the synthesis of glycerol and ammonia toward pyridine bases in a series-connected two-stage reactor. The characterization was analysed by means of N2-physorption and NH3-TPD techniques. The catalytic evaluation showed that the lower Si/Al ratio (Si/Al = 25 before treatment) in catalyst pairs (HZSM-5-At + ZnO/HZSM-5-At-acid) possessed the highest total yield of pyridine bases among all the catalyst pairs, but the suitable Si/Al ratio in alkaline-treated ZSM-5 (Si/Al = 38 before treatment) in the first stage of reactor and ZnO/HZSM-5-At-acid (Si/Al = 25 before treatment) in the second stage of reactor had the stronger stability relative to other catalyst pairs. The characterization revealed that the amount of acid sites play a vital role in the formation of pyridine bases whereas the appearance of mesoporous structure and the declined concentration of acid sites were main reasons for promoting the stability.

Enhanced selectivity in the conversion of glycerol to pyridine bases over HZSM-5/11 intergrowth zeolite

Intergrown zeolite HZSM-5/11(78) catalyst showed enhancement in the conversion of glycerol with ammonia to pyridine bases.