J. Soc. Cosmet. Chern. 0.0. 201-210 (1971) ¸ 1971 Society of Cosmetic Chemists of Great Britain Polyethoxy cholesterols j. SCOTNEY and E. V. TRUTER* Presented on 6th October 1970 in London at the Symposium on "New developments in lanolin and its derivatives", organised by the Society of Cosmetic Chemists and the Society of Cosmetic Chemists of Great Britain. Synopsis--Individual ETHOXY CHOLESTEROLS have been isolated from SYNTHETIC mixtures by laminar CI-IRO•ATOGRAPI-IY, and their effects on the benzene/water INTERFACIAL TENSION has been measured by the pendant drop method. The results indicate that the PROPERTIES of ethoxy condensates of WOOL WAX ALCOHOLS, which have been analysed briefly, could be improved by fractionation. INTRODUCTION Nonionic surface-active substances derived by the condensation of ethylene oxide with suitable hydrophobic compounds have many appli- cations as o/w emulsifying agents. Polyethoxy derivatives of wool wax alcohols (1) have many uses in cosmetics several grades are available under the name Polychol©N, where N is the molar ratio of ethylene oxide to alcohol in the mixture when the condensation reaction is initiated. The concept of the hydrophil-lipophil (H/L) balance suggests that the Polychols should possess a wide range of properties. In reality, however, the Polychols in which N may have selected values up to 40, have surprisingly similar properties, and are only moderately good emulsifying agents. One reason for their indifferent performance may lie in the heterogeneity of the parent wool wax alcohols (Hartdan©) which contain three main classes of com- pounds aliphatic long-chain alcohols, cholesterol and its congeners, and lanosterol and its congeners. If these classes of alcohols react with ethylene *Textil• Chemistry Laboratory, The University, Leeds, LS2 9JT. 201

202 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS oxide at different rates, the H/L balances for the three series will be differ- ent. Consequently, when one series has been brought to its optimum H/L balance, the other series will be off balance. Another possible source of im- perfection is that each parent alcohol will be distributed among several homologues having a range of N-values and, therefore, a range of H/L balances. If the range is too wide, the surface-active properties of the series will be adversely affected. One object of this study was to examine the way in which ethoxy units are distributed in the products of the reaction of ethylene oxide with an alcohol. A second objective was to explore the effect of molecular structure on surface activity by measuring the decrease in the benzene/water inter- facial tension caused by individual ethoxy compounds. EXPERIMENTAL Preparation of elhoxylates (a) Ethylene oxide (1 ml about 5 equivalents) was added to a cold (--10øC) mixture of cholesterol (2 g), benzene (20 ml) and sodium (0.1 g), and the tube was sealed and set aside at room temperature. After 4 months the tube was opened and the contents were evaporated to dryness under reduced pressure. (b) A second preparation differed only in the quantity of ethylene oxide (5 ml 25 equivalents) and the reaction time (6 weeks). Similar preparations containing lanostenol (=dihydro-lanosterol) (2 g) plus ethylene oxide (1 ml) and n-octadecanol (3 g) plus ethylene oxide (1 ml) were also set aside for 4 months. Chromatography Standard methods of laminar chromatography were used except where specified. Glass plates were coated with Silicagel G (Merck) using the Shan- don apparatus. For normal work the spreader gap was 0.3 mm and for pre- parative chromatography it was 0.6 mm. Chromatograms were developed in tanks which had been lined with filter paper soaked in solvent all eluent compositions are expressed in volumes. Sulphuric acid was the usual chromogenic reagent in the cold, cholesterol derivatives were easily distinguished because they gave reddish- purple spots whereas derivatives of the other alcohols remained colourless.