GB625131A - Improvements in or relating to the manufacture of diethyl acetal - Google Patents

Abstract

Diethyl acetal is made by reacting acetaldehyde with ethanol in presence of an acidic catalyst and an inert diluent, which is immiscible with water and which has a distribution coefficient for the acetal in relation to water which is at least double that for the alcohol and aldehyde, in an amount at least sufficient to cause the major proportion of the water in the reaction mixture to separate out as an aqueous phase, intimately mixing the reactants during the reaction, either continuously or intermittently, with the said diluent, separating the two phases formed and recovering the acetal from the diluent phase by distillation. The acetal may be recovered from the aqueous phase also. The diluent may be added before or after the reaction has started, and may boil at 120-200 DEG C.; ethanol or acetaldehyde may be present in excess, e.g. 10-20 per cent excess ethanol. Catalysts specified are sulphuric and phosphoric acids. The reaction temperature is preferably below 30 DEG C. The process may be carried out continuously in which case the mixing may be effected by turbulence in narrow tubes. The catalyst is preferably added last after cooling. Examples describe the reaction of acetaldehyde and ethanol in presence of sulphuric acid, using as diluent: (1) kerosene; (2) benzene; (3) n-hexane; (4) carbon tetrachloride. Specification 282,112, [Class 1 (i)], is referred to.