GB762138A - Improvements in or relating to processes for the preparation of hydracrylic esters - Google Patents

Abstract

Hydracrylic esters are obtained by reacting carbon monoxide with ethylene oxide at between 60 DEG and 100 DEG C. under raised pressure and in the presence of water, a cobalt carbonylation catalyst, and if desired an alcohol. Small amounts of phenolic compounds, e.g. hydroquinone, may be included in the reaction mixture to increase the velocity of the reaction. Specified alcohols which may be present are methanol, ethanol and ethylene glycol and when these alcohols are present the corresponding hydracrylic esters are obtained in addition to the ethylene glycol monohydracrylate which is formed from the carbon monoxide, ethylene oxide and water. Specified cobalt catalysts are cobalt carbonyl hydride and reduced cobalt deposited on a support such as kieselguhr. The reaction is preferably carried out at 70-75 DEG C. and at a pressure of 100 to 200 kilograms per square centimetre. The ethylene glycol monohydracrylate may be trans-esterified to form other hydracrylates, e.g. the methyl and ethyl hydracrylates. In examples for the production of ethylene glycol mono-hydracrylate: (1) ethylene oxide is reacted in an autoclave with carbon monoxide in the presence of water, the catalyst being reduced cobalt on kieselguhr; (2) as in (1) except that a small amount of hydroquinone is also present; (3) as in (2) except that the catalyst is first formed in the autoclave by depositing cobalt carbonate on kieselguhr and treating with carbon monoxide and water (see Group III), some cobalt hydracrylate is also formed in the main reaction; (4) as in (3) except that glycol is also present. The hydracrylic esters may be converted to hydracrylamide by the action of ammonia and the amide may be dehydrated to form acrylamide which may be converted by further dehydration into acrylonitrile. Alternatively, the two dehydrations may be effected in a single stage by passing hydracrylamide over a catalyst of the active alumina type at about 300 DEG C. The esters may also be dehydrated to form the corresponding acrylates by passing them over an active alumina catalyst at a suitable temperature, thus ethyl hydracrylate may be converted to ethyl acrylate in this way.ALSO:Cobalt carbonyl hydride which may be used as a catalyst in the reaction of carbon monoxide with ethylene oxide and water to form hydracrylic esters (see Group IV(b)) may be obtained by the action of carbon monoxide on cobalt or its salts in the presence of water. In an example it is obtained by heating a mixture of water and cobalt carbonate deposited on kieselguhr in an autoclave at 100 DEG C. with carbon monoxide at a pressure of 90 kilograms per square centimetre.