GB264791A - Manufacture of acetals - Google Patents

Abstract

264,791. Consortium fur Elektrochemische Industrie Ges. Jan. 25, 1926, [Convention date]. Addition to 257,622. Acetals; acetaldehyde.-The process of making acetals which consists in treating monohydric or polyhydric alcohols with acetylene in the presence of a mercury salt and continuously removing the acetal produced, as described in the parent Specification, is now modified by using alcohol containing water, which is converted into acetaldehyde. To increase the proportion of acetal in the product, the mixed vapour from the reaction mixture may be partly condensed, and the condensate returned to the reaction mixture, or the products may again be passed through the apparatus several times. The acetaldehyde formed may be fractionated out of the vapours, or removed therefrom by washing, say with the alcohol used in the reaction. A portion of the liquid reaction mixture may be withdrawn continuously or intermittingly, so that mercury sludge may be removed, and the composition of the liquid adjusted; the reaction liquid may be circulated for this purpose. In examples, (1) a suspension of mercury sulphate in ethyl alcohol of 92 per cent strength is heated to about 70‹ C. and acetylene passed in. After condensing out the vapours escaping from the reaction mixture; the unconverted acetylene is returned with the fresh gas. An emulsion of mercury sulphate in the water-contaminated alcohol is added to the reaction mixture; fresh alcohol is also added: (2) the process is conducted as in the preceding example, but in a reaction vessel with a, fractionating apparatus so that a part of the vapour distilling is condensed and returned to the reaction vessel. The product may contain 40 per cent or more of acetal and 15 per cent of aldehyde; (3,) the product from Example (2) is again passed through the reaction apparatus, using a more concentrated emulsion. A product containing 62 per cent acetal and 16 per cent aldehyde may thus be obtained.