Kinetics and mechanism of the liquid-phase reaction of 2,4-dinitrotoluene with ozone in the presence of manganese(II) acetate

Galstyan, A. G.; Lysak, V. V.; Galstyan, G. A.

doi:10.1134/s0023158413060050

Cited by 2 publications

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“…Згідно з експериментальними даними та відомостями фахової літератури [9,10], запропоновано таку схему каталітичного окиснення 2-ацетокситолуолу озоном у розчині стоп-реагенту: Як показали оцінні розрахунки, реакції (6-8) перебігають істотно повільніше, ніж реакція ініціювання (3) та реакція рекомбінації радикалів (11) або ( 14), тобто окиснення за метильною групою здійснюється, імовірно, за іонно-радикальним неланцюговим механізмом. Про неланцюговий механізм свідчать і такі факти: селективність окиснення за метильною групою досягає максимуму при зіставних концентраціях субстрату і каталізатора, витрата озону на 1 моль субстрату близька до теоретичного, припинення подачі озону в зону реакції призводить до відновлення Мn (III) до Мn (II).…”

Section: обговоренняunclassified

Ozonolytic synthesis of 2-hydroxybenzyl alcohol for the production of gastrodin

Halstian¹,

Hasanova²,

Tarasenko³

2023

АП

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2-Hydroxybenzyl alcohol is an important active pharmaceutical ingredient for the production of many drugs, in particular gastrodin, which has a wide range of beneficial effects on epilepsy, Alzheimer’s disease, Parkinson’s disease, affective disorders, cerebral ischemia, cognitive disorders. It is known that 2- and 4-hydroxybenzyl alcohols and mixtures of both compounds are obtained by the interaction of phenol with formaldehyde in the presence of basic catalysts. Due to its high reactivity with formaldehyde, the isolation of pure compounds from the reaction mixtures obtained during the interaction of phenol with formaldehyde is a big problem. Isolation of 2-hydroxybenzyl alcohol in pure form from reaction mixtures is possible only using processes that cannot be carried out on an industrial scale and is accompanied by low yields of the target product. It is possible to get rid of these problems by means of the process of direct oxidation of the 2-hydroxytoluene with ozone in the liquid phase since methods of selective ozonation of methylbenzene to the oxygen derivatives are already known. Therefore, the development of a new low-temperature synthesis of 2-hydroxybenzyl alcohol using ozone is an urgent task. The aim of the work is to study the reaction of the oxidation of 2-hydroxytoluene by ozone in a solution of a stop reagent and catalytic impurities of compounds of transition metals and mineral acids for the development of a new method of synthesis of 2-hydroxybenzyl alcohol. Materials and methods. For the experiments, acetic anhydride of p. a. qualification was used; glacial acetic acid of puriss. qualification, which before use was purified by distillation under vacuum in the presence of potassium permanganate, 2-hydroxytoluene of puriss. Qualification, manganese (II) acetate of pur. Qualification, sulfuric and phosphoric acids of puriss. qualification. To determine the concentration of ozone in the gas phase, a spectrophotometric method was used, based on the measurement of the optical density of the gas flow in the UV region. For this purpose, a spectrophotometer SF-46 LOMO was used, in the measuring chamber of which a flow cuvette with quartz windows was installed. The material of the cuvette was Teflon. Continuous monitoring of the current concentration of ozone, with the recording of the analysis results in the form of a kinetic curve, was carried out when ozone-containing gas passed through the curette at a certain wavelength of a monochromatic light source. Results. The reaction of oxidation of 2-hydroxytoluene by ozone in a solution of the stop reagent – acetic anhydride was studied. It was shown that in the presence of sulfuric acid, it was possible to carry out direct ozonation of 2-hydroxytoluene to 2-hydroxybenzyl alcohol, which was formed in the kind of 2-acetoxybenzyl acetate with a yield of 13.0 %. The main products of the reaction under these conditions are aliphatic compounds, which are formed after the destruction of the aromatic ring. The selectivity of oxidation by alcohol was significantly increased when a catalyst – manganese (II) acetate – was added to the system. In its presence, a catalytic system As2O – H2SO4 – Mn(III) was created, which prevents ozonolysis and directed oxidation mainly to the methyl group of the substrate with the formation of 2-acetoxybenzyl acetate with a yield of 63.2 %. Conclusions. An environmentally friendly, low-temperature method for the synthesis of 2-hydroxybenzyl alcohol was developed by conducting the oxidation of 2-hydroxytoluene with ozone in a solution of the stop reagent – acetic anhydride in the presence of sulfuric acid and manganese (II) acetate.

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Section: обговоренняunclassified

Ozonolytic synthesis of 2-hydroxybenzyl alcohol for the production of gastrodin

Halstian¹,

Hasanova²,

Tarasenko³

2023

АП

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Catalytic oxidation of toluene by ozone in the system "acetic anhydride–strong acid"

Potapenko¹,

Andreev²,

Isayenko³

et al. 2021

Vopr. Khim. Khim. Tekhnol.

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The process of catalytic oxidation of toluene by ozone in the solution of a mixture "acetic anhydride–a strong acid" has been studied in the presence of compounds of transition metals. It is shown that the main oxidation products in the system Mn(Ac)2–(СН3СО)2О–Н2SO4 at 200C are benzylacetate and benzylidene diacetate with the yields of 39% and 29%, respectively. In the system Со(Ac)2–(СН3СО)2О–НА, the reaction is accompanied mainly by the formation of benzylidene diacetate (68.0%) and the yield of benzylacetate does not exceed 4.0%. The kinetic parameters of the main stages of the catalytic cycle were investigated. It was found that strong acids play a decisive role in increasing the activity of oxidized forms of the metal. Under the conditions of activation by strong acids, the reaction of methylbenzene with Me3+ occurs with a high degree of substrate conversion. It was found that the reduction of Me3+ in the reaction with the solvent becomes noticeable, along with the oxidation of toluene, with increasing the concentration of strong acids. It was stated that the selective oxidation of toluene under catalysis is initiated by the reaction with an oxidized form of the metal formed by the interaction of ozone with the catalyst.

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Kinetics and mechanism of the liquid-phase reaction of 2,4-dinitrotoluene with ozone in the presence of manganese(II) acetate

Cited by 2 publications

References 1 publication

Ozonolytic synthesis of 2-hydroxybenzyl alcohol for the production of gastrodin

Ozonolytic synthesis of 2-hydroxybenzyl alcohol for the production of gastrodin

Catalytic oxidation of toluene by ozone in the system "acetic anhydride–strong acid"

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