Process for the production of alcohols

摘要

Alcohols are obtained from acetals or semiacetals by treating with hydrogen and water in the presence of a hydrogenation catalyst at an elevated temperature and pressure. Starting materials are acetals of formula and semi-acetals of formula in which R1 is hydrogen and R2 and R3 are aliphatic hydrocarbon radicals. Suitable catalysts are, for example, a mixture of nickel, magnesium oxide and kieselguhr, a mixture of cobalt, thorium oxide, magnesium oxide and kieselguhr, and Raney nickel. The preferred temperature range is 100-220 DEG C. and the pressure should be above 10 kg. per cm.2. Hydrogen or a mixture of hydrogen with inert gases such as nitrogen and methane may be used as the hydrogenating gas. The process is particularly suitable for obtaining pure alcohols from synthetic mixtures which contain alcohols and aldehydes in addition to hydrocarbons. Additional alcohols or aldehydes may be added to the mixture if required if the original ratio of aldehyde to alcohol does not correspond to the ratio needed for the formation of acetals. In the examples (a) AC30 acetal is obtained by heating a mixture of C10 alcohol and C10 aldehyde with hydrochloric acid and benzene. The acetal is mixed with water and a nickel-magnesia-kieselguhr catalyst and treated with hydrogen at elevated temperature and pressure to give a C10 alcohol; (b) a C7 aldehyde is produced, using a cobalt catalyst, by the addition of water-gas to a hydrocarbon fraction containing C6-olefinic hydrocarbons and is mixed with a C6 alcohol, a small amount of oxalic acid is added and the mixture heated; the semiacetal found is mixed with water and a reduced nickel-magnesia-kieselguhr catalyst and heated with hydrogen at elevated temperature and pressure to give a C7 alcohol; (c) a product of the catalytic hydrogenation of carbon monoxide is heated with a caustic soda; the product is treated with water-gas in the presence of cobalt sulphate to give a mixture containing acetals and semi-acetals, the mixture is treated with water and hydrogen in the presence of a nickel-magnesia-kieselguhr catalyst at elevated temperature and pressure to give a mixture of alcohols.