Reaction of toluene with ozone in the liquid phase

Galstyan, A. G.; Galstyan, S. G.; Tyupalo, N. F.

doi:10.1134/s1070427210020151

Cited by 5 publications

(4 citation statements)

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“…Позбутися цих проблем можна шляхом прямого окиснення відповідного 2-гідрокситолуолу озоном у рідкій фазі, оскільки вже відомі методи селективного озонування метилбензолів до відповідних оксигенпохідних [3][4][5][6]. Отже, актуальним є розроблення нового низько-температурного синтезу 2-гідроксибензилового спирту за допомогою озону.…”

Section: Ozonolytic Synthesis Of 2-hydroxybenzyl Alcohol For the Prod...unclassified

“…Відомо [6], що реакція фенолів з озоном відбувається з високою швидкістю (k = 10 2 ÷ 10 3 л·(моль•с) -1 ) за НО-групою субстрату з наступним руйнуванням бензольного кільця. Під час дослідів, що здійснили, як розчинник використали оцтовий ангідрид, який швидко ацилює 2-гідрокситолуол уже в процесі приготування розчину для окиснення.…”

Section: результатиunclassified

“…Бензиловий спирт 0,20 ÷ 0,75 5,8 ÷ 14,8 3,40 ± 0,30 [6] Бензальдегід 0,20 ÷ 0,75 6,8 ÷ 10,8 2,30 ± 0,20 [6] 2-Гідроксибензиловий спирт 0,37 ÷ 0,57 1,1 ÷ 1,5 34,16 ± 3,51 2-Гідроксибензальдегід 0,37 ÷ 0,57 1,1 ÷ 1,5 71,50 ± 7,20…”

Section: результатиunclassified

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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: Ozonolytic Synthesis Of 2-hydroxybenzyl Alcohol For the Prod...unclassified

Section: результатиunclassified

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

Halstian¹,

Hasanova²,

Tarasenko³

2023

АП

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“…6, when the other conditions remained unchanged, with ozone concentration of 0-30 mg/l, PX conversion rate and selectivity of TA increased significantly, selectivity of 4-CBA and PT decreased significantly. This was because the presence of ozone could not only directly promote the oxidation of methyl groups in PX to aldehydes and carboxyl groups 10 , but also accelerate the conversion of Co 2+ to Co 3+ in the system to shorten the chain initiation time and speed up the oxidation reaction. When the ozone concentration was between 30 and 63 mg/l, the conversion of PX and the selectivity of TA continued to increase steadily to a moderate extent; the selectivity of PT decreased continuously, while the selectivity of 4-CBA remained constant at about 3%.…”

Section: Effect Of Ozone Concentrationmentioning

confidence: 99%

p-Xylene catalytic oxidation to terephthalic acid by ozone

Helin¹,

Li²,

Shu³

et al. 2018

ScienceAsia

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The process of p-xylene (PX) catalytic oxidation to terephthalic acid (TA) was studied at 60-110°C and atmospheric pressure with cobalt acetate as catalyst, glacial acetic acid as solvent, and ozone-containing air as oxidant. Effects of catalyst, temperature, ozone concentration, reaction time, and bromide on PX conversion and product selectivity were investigated. Results showed that PX was oxidized with 76% conversion and 84% selectivity for TA at 80°C under 63.0 mg/l ozone concentration for 6 h at 0.8 l/min gas flow rate when the mole ratio of PX to cobalt acetate was 10:1. PX conversion and TA selectivity could reach 96% and 84% when the mole ratio of PX to KBr was 1.84:1. When cobalt acetate, ozone, and bromide were simultaneously used, an obvious synergistic effect on the PX oxidation reaction was noted. Increasing the temperature gradually weakened the effect because the decomposition rate of ozone was accelerated.

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