METHOD OF CONTINUOUSLY PREPARING 3-(METHYLTHIO) PROPANAL (VARIANTS) Russian patent published in 2000 - IPC

FIELD: chemical industry. SUBSTANCE: described is method of continuously preparing 3-(methylthio) propanal which comprises contacting gaseous stream of acrolein-containing stock with liquid reaction medium in gas and liquid contacting zone. Said reaction zone contains 3-(methylthio) propanal, methylmercaptan and catalyst of reaction between mercaptan and acrolein, and gaseous stream of acrolein-containing stock contains acrolein vapors and uncondensable gas, relative amounts of acrolein and methylmercaptan present in containing one being substantially stoichiometrically equivalent due to which fact acrolein is transferred from stream of stock into reaction medium and is directly reacted with methylmercaptan without formation of intermediate hemi(methylthio)acetal of 3-(methylthio) propanal to give liquid reaction product comprising 3-(methylthio) propanal; uncondensable gas is separated from liquid reaction product; said reaction product is separated into product fraction and circulating fraction; and circulating fraction is recycled into gas and liquid contacting zone. Acrolein and methylmercaptan are reacted in liquid medium in reaction zone which includes gas and liquid contacting zone and circulation zone which admits liquid reaction product from gas and liquid contacting zone and through which zone circulating fraction is recycled into gas and liquid contacting zone; mercaptan is admitted into said reaction zone over such area or areas not to allow excessive amount of methylmercaptan of promote any substantial formation of intermediate hemi(methylthio)acetal in any sector of reaction zone for sufficiently prolonged period of time. EFFECT: simplified process and high-grade desired product which need not be purified. 14 cl, 8 dwg, 30 ex, 5 tbl