| 摘要 |
Ethylidene (or substituted ethylidene) diesters of carboxylic acids are obtained by subjecting acetaldehyde or a substituted acetaldehyde to reaction with a mixture comprising a free carboxylic acid and the anhydride of a different carboxylic acid in the presence of an acid catalyst to obtain a reaction product comprising a mixture of ethylidene (or substituted ethylidene) diesters. Also, a mixture of vinyl (or substituted vinyl) esters of carboxylic acids is obtained by reacting acetaldehyde or substituted acetaldehyde with a mixture comprising a free carboxylic acid and the anhydride of a different carboxylic acid to produce a mixture of ethylidene (or substituted ethylidene) diesters and decomposing said diesters to produce a mixture of vinyl esters of said carboxylic acids, both the production and the decomposition of the ethylidene diesters being carried out in the presence of an acid catalyst. One or more carboxylic acids and one or more carboxylic acid anhydrides may be used. It is preferred to use a mixture of acetic anhydride with propionic, butyric or pentanoic acid and to use between 1 and 10 moles of the anhydride for each mole of acetaldehyde and the quantity of carboxylic acid should range from about 0,05 to 1,0 mole for each mole of the anhydride. Specified acid catalysts are sulphuric acid, alkane sulphonic acids, and aromatic sulphonic acids. The ethylidene diester-forming reaction is best carried out at between 120 and 160 DEG C. and will then normally require from 0,5 to 2 hours to to to completion. The decomposition of the ethylidene esters is suitably affected at temperatures of at least 130 DEG C. and the vinyl esters are preferably removed from the reaction zone, e.g. by distillation, as they are formed. They may be separated from one another by fractional distillation. A small amount of a polymerization inhibitor may be present in the reaction zone. It is preferred to carry out the production of the ethylidene diesters and their conversion to the vinyl esters in a single reactor and the process may be carried out batchwise or in a continuous manner. Examples are given for the production of a mixture of (1) vinyl acetate and vinyl propionate and (2) vinyl acetate and vinyl butyrate. Specification 576,397 is referred to. |
