Other

Alexandr P Khardin

Anatoly I Lukashov

Vitaly Vasilievich Orlyansky

Boris Nikolaevich Gorbunov

Valentin M Belyaev

Boris N Gorbunov

Lidia Vladimirovna Erokhina

Vladimir L Rudkovsky

Galina Dmitrievna Efremova

Daniil Iosifovich Valdman

Ljudmila V Shpantseva

Pavel Y Gokhberg

Alexandr I Valdman

Vyacheslav K Rykov

Evgeny Maximovich Kukartsev

Ideya Antonovna Churikova

Stanislav V Sukhanov

A method of producing acrolein comprising evaporating acetaldehyde and formaldehyde in the presence of diphenyl-N-nitrosamine taken in an amount of from 0.1 to 3 wt. %. The resultant vapors of said aldehydes are fed for aldol condensation which occurs in a gaseous phase on a catalyst, viz., coarsely porous silica gel promoted by 10 to 12 wt. % sodium silicate at a temperature of from 270.degree. to 300.degree. C. in the presence of diphenyl-N-nitrosamine taken in a quantity of from 0.1 to 3 wt. %. The resultant gas mixture formed at the stage of aldol condensation, containing acrolein, acetaldehyde, formaldehyde and water is cooled to obtain a condensate. Said condensate is subjected to rectification in order to isolate a mixture of acrolein with acetaldehyde and water, and an aqueous formaldehyde solution. Said aqueous formaldehyde solution is concentrated and returned to the aforesaid evaporation stage. Said mixture of acrolein with acetaldehyde and water is subjected to rectification in the presence of diphenyl-N-nitrosamine taken in an amount of from 0.1 to 3 wt. % in order to isolate the end product alongside with acetaldehyde containing from 0.2 to 1.5 wt. % acrolein and returned to the aforesaid evaporation stage. The proposed method makes it possible to avoid completely resinification at the stage of evaporation of aldehydes, to run aldol condensation of acetaldehyde with formaldehyde at a continuous discharge of resins as they form, to carry out rectification of a mixture of acrolein with acetaldehyde and water continuously as well as to substantially increase the purity of the acrolein produced (the acrolein content in the distillate being within 91 to 93 percent).

Method of producing acrolein

The method of preparing isoprene and isoamylenes consists in that a gaseous mixture of isobutylene and methyl alcohol is brought in contact with a catalyst, namely aluminum oxide or tantalum pentoxide, at a temperature of 250 to 500.degree. C. It is recommendable that use should be made of aluminum oxide modified with an oxide of at least one of the following elements: molybdenum, tungsten, chromium, zirconium, titanium, vanadium, and cobalt. Moreover, it is possible to use aluminum oxide modified with a sulphate of at least one of the following elements: zirconium and chromium. A combination of both modifications is also possible. The yield of isoprene obtained by the proposed method is 16 to 20 mol. percent, with respect to the passed methyl alcohol, and the yield of isoamylenes is 25 to 30 mol. percent.

Method of preparing isoprene and isoamylenes

The method of preparing 4,4-dimethyldioxane-1,3 consists in the interaction of isobutylene and formaldehyde in an aqueous medium at from 90.degree. to 115.degree. C in the presence of a catalyst, the capacity of which such inorganic salts of mineral acids may be used with the pH value of the aqueous solutions whereof being within 2.2 to 4.5, resulting in the formation of an organic and an aqueous phase containing the end product, followed by the separation of said phases, washing the organic phase with water, and isolation of the end product. When a catalyst of such salts is used, the acidity of the aqueous solutions of which is either invariable or decreases with an increase in the salt concentration, it is expedient that the aqueous phase and the wash water be evaporated to a level of from 85 to 90 percent to form a fraction containing the unreacted formaldehyde, and a distillation residue which is in fact an oil bed and a salt bed with the latter, after having been separated, being returned to the stage of interaction of the starting reagents.

Method of preparing 4,4-dimethyldioxane-1,3

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Volgograd, undefined

Alexandr P Khardin