GB750609A - Process for the preparation of organic sulphates - Google Patents

Abstract

Sulphate ester salts having the general formula R1R2R3.C-O-SO3Me, wherein the R' may be the same or different alkyl, aralkyl, aryl, cycloalkyl or cycloalkyl-alkyl groups, which may contain substituents such as hydroxyl, carboxyl or ester groups, or one or two of the R's may instead be hydrogen atoms, and Me represents an alkali metal, are prepared by reacting the corresponding hydroperoxides R1R2R3.C-OOH with alkali bisulphite in aqueous solution, using less than one mol. of bisulphite per mol. of hydroperoxide whereby the product formed consists predominantly of the desired organic acid sulphate salt. A small amount of sulphonic acid of the formula R1R2R3.C-SO3H, the R's being as defined above, is formed as by-product and may be separated from the main product, if desired. The hydroperoxide is preferably reacted in solution in a hydrocarbon or in the corresponding non-peroxidized starting material. The hydroperoxides employed are preferably derived from petroleum fractions in the C10-C35 range, fatty acids and vegetable oils having an iodine value below 150 such as olive oil; these hydroperoxides yield surface-active acid sulphate salts. The hydroperoxides may be prepared by passing oxygen or air through the hydrocarbon, e.g. a petroleum fraction B.R. 150-450 DEG C., or other starting material at elevated temperature and, if desired, in the presence of metallic soaps, e.g. the stearates or naphthenates of alkali, alkaline-earth or polyvalent metals, as accelerators. In an example, a petroleum fraction B.R. 250-300 DEG C. free from reactive sulphur compounds and having an aromatic content of below 10 per cent is partially peroxidized with finely-divided air at 100-105 DEG C. and is then reacted with 0.5-0.7 mols. sodium bisulphite in aqueous solution per mol. of hydroperoxide, with cooling to maintain a temperature not above 30-35 DEG C. The mixture is then settled, and there form a bottom aqueous layer, a median layer of ester-sulphate salts containing by-product sulphonate and hydrocarbons and a top layer of hydrocarbons which can be used again in the process. The sulphate salt layer is washed with benzene or light naphtha and then stripped of solvent, yielding a mixture of ester-sulphate salts (80 per cent) and sulphonates. Specifications 695,547 and 728,504 are referred to.