process for preparing sulfonated fatty acids or fatty acid derivatives and their salts containing any of a light colour.

摘要

The invention comprises a process for bleaching sulpho-fatty acids, esters or nitriles, which compounds (a) have 6 to 28 carbon atoms, (b) are derived from compounds containing no sulphonatable or sulphatable groups other than the hydrogen atom or the acid a -carbon atom, (c) have been prepared by sulphonation using a sulphur trioxide-inert gas mixture in the absence of solvents and (d) contain 0.05 to 1 mole of sulphur trioxide per mole of fatty acid residue, using an aqueous solution or dispersion of an inorganic bleaching agent, which may be prepared in situ, containing such a quantity of water that the sulphuric acid produced by solution of the sulphur trioxide contained in the sulpho-fatty acid is at least 20% by weight sulphuric acid solution and at most a 95% by weight aqueous solution of sulphur trioxide, discounting any water which may be produced by degradation of the bleaching agent. Exemplified sulpho-fatty acids are derived from hydrogenated or hardened tallow fat acid, coconut fat acid, and palm kernel acid, ethyl esters thereof, mixtures of the above, ethyl caprylate, palmitonitrile and palmitic acid. Bleaching agents specified are hydrogen peroxide, compounds which form hydrogen peroxide during the process, for example hydrogen peroxide salts, peroxyhydrates and addition compounds of hydrogen peroxide with organic compounds, and inorganic oxy acids and their salts and anhydrides, or combinations thereof. Bleaching may be effected at 20 DEG to 100 DEG C. Esterification of the sulpho-fatty acid may be effected before or after bleaching. The products may be further bleached after neutralization, optionally as salts. Excess sulphur trioxide in the starting material may be reacted prior to bleaching with compounds having an aliphatic hydroxyl group whose sulphation products have surface-active properties. Specification 1,001,285 is referred to.