Kinetic regularities of α-ethylacrolein and crotonic aldehyde oxidation in methanol, allyl alcohol and glycidol were studied. Rate constants of hydrogen peroxide consumption and rate constants of unsaturated acid and its ester accumulation for both aldehydes in different alcohols at various catalyst concentrations and temperatures were calculated. The reaction activation parameters were also calculated. Dependences of ester/ acid ratio on the reaction conditions were ascertained. Dependence of the reaction rate and the reaction products composition on aldehyde and alcohol structures was shown. Data of the reaction products composition dependence on the reaction conditions conform to the reaction kinetic parameters.
Catalytic performance of Se-containing organic substances, namely methylseleninic acid, benzeneseleninic acid, phenylselenol and diphenyldiselenide, has been tested as potential catalysts for unsaturated aldehydes oxidation by hydrogen peroxide. All tested substances proved to be active in the acrolein oxidation reaction but showed different efficiency regarding used solvents and the products of reaction-acrylic acid or methyl acrylate. Optimal catalyst, reaction conditions and solvent for acrylic acid synthesis have been determined.
Exotherm verlaufende Oxidationen der Acroleine (I) mit H2O2 in Gegenwart von SeO2 oder H2SeO3 in tert.‐Butanol liefern mit hoher Selektivität die Acrylsäuren (II).
The new data about oxidation of unsaturated aldehydes of a general structure R –CH = C(R)–CHO by molecular oxygen (in liquid and gaseous phase), peracids and hydrogen peroxide were obtained. The composition of reaction products for a series of aldehydes with different structures was determined. The dependencies of the selectivity of reaction from an aldehyde structure and oxidant type have been evaluated. It has been assumed that a stage of aldehyde interaction with peracid determines the formation of reaction products. The common mechanisms of unsaturated aldehydes oxidation by different oxidants have been established on the basis of generalization of obtained results.
Досліджено процес газофазної конденсації метилпропіонату та пропіонової кислоти з формальдегідом із утворенням метакрилової кислоти та метилметакрилату в присутності каталізаторів на основі оксидів бору і фосфору, промотованих сумішшю оксиду цирконію та основного оксиду. Встановлено вплив температури на конверсію, селективність і вихід цільових продуктів. Встановлено, що додавання метанолу підвищує селективність утворення метилметакрилату та сумарний вихід акрилатів. Ключові слова: метакрилова кислота; метилметакрилат; пропіонова кислота; альдольна конденсація; каталізатор; метилпропіонат; формальдегід.
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