GB756334A - Improvements in or relating to the production and/or separation of non-ionic surface active agents - Google Patents

Abstract

756,334. Fractionation of ethylene oxide condensation products. BRITISH PETROLEUM CO., Ltd., [formerly ANGLO-IRANIAN OIL CO., Ltd.], DESTY, D. H., and HARBOURN, C. L. A. Dec. 3, 1953 [Dec. 31, 1952], No. 33051/52. Class 2 (3). A non-ionic surface active agent comprising a mixture of non-ionic surface active compounds containing, in the molecule, a chain of ethylene oxide groups, is separated into fractions differing in surface active characteristics by adding to a solution of the surface active agent in an organic solvent, a precipitating agent in which the surface active agent is only partially soluble, the precipitating agent being a liquid miscible with the solvent, whereby part of the surface active agent is thrown out of solution to form a precipitated fraction which is recovered. The precipitated fraction contains an increased proportion of compounds having relatively long ethylene oxide chains compared with the compounds remaining in solution. A plurality of precipitated fractions may be obtained by progressive additions of the precipitating liquid or by progressively lowering the temperature. The surface active agents may be prepared by reaction of ethylene oxide with a suitable organic compound containing an -OH or -SH group, for example a fatty acid, resin acid, alcohol, alkylated phenol or mercaptan. The mixture so obtained may be fractionated as described above, and after removal of the precipitated fractions, the solution may be distilled to remove solvent and precipitating agent to give the residue comprising compounds with short ethylene oxide chains which may be recycled to the reaction mixture comprising ethylene oxide and the organic compound. Specified solvents are ethanol, acetone, benzene, toluene, cyclopentane, cyclohexane, carbon tetrachloride and chloroform, cyclohexane being preferred. Specified precipitating agents are iso- or normalpentane or hexane or heptane and iso-octane, iso-hexane being preferred. In examples, a liquid non-ionic surface active agent of formula wherein R is an alkyl group of, on average, 8 carbon atoms, A is a benzene ring and n is approximately 12, is dissolved in cyclohexane and two-thirds thereof is precipitated in two fractions by the progressive addition of isooctane, the remainder being recovered after distillation of the solution. The fractions are reacted with urea as described in Specification 697,315 and the solid products obtained compared with the corresponding product from the unfractionated material.