THE SUGAR ESTERS IN COSMETICS* By L•OYD OsiPo v Foxter D. She//, Inc., New York ll, N.Y. Studies on the sugar esters were initiated with the primary objective of providing low cost detergents for household use which would utilize excess sugar production capacity. However, this development has elicited considerable interest on the part of the food, cosmetic and pharmaceutical industries because of the unusual character of these esters. The sugar monoesters of fatty acids are the only water-soluble surface-active agents to be made available which are either natural foods or which hydrolyze to form natural food products. Sucrose and raffinose monoesters of fatty acids are new chemicals. Nonetheless, their potential usefulness is such that it can be anticipated that the transition from laboratory preparation to t•ll-scale commercial production will be rapid. PROCESS FOR MANUFACTURE OF THE SUGAR ESTERS The commercial process for the manufacture of the sugar esters is quite simple. To obtain the monoester, three moles of sugar are dissolved in a solvent such as dimethylformamide. One mole of a methyl ester of a fatty acid and about 0.1 mole of an alkaline catalyst are added. The mixture is maintained at about 90øC., under a vacuum corresponding to the vapor pressure of the solution at this temperature. An alcoholysis reaction occurs. The methyl alcohol portion of the methyl ester is replaced by sucrose to form the sugar ester of the fatty acid and methanol. Under these conditions of temperature and pressure, the methanol is removed as it is formed, * Presented at the November 30, 1955, New York Chapter Meeting, New York City. TABLE 1 CoNvERSiON ov METHYL STEARATE TO SUCROSE MONOSTEARATE Material Present After Indicated Time •--Percentages Based on Alcohol Solubles---•, 3 Hr. 6 Hr. 9 Hr. 12 Hr. Sucrose monostearate 36.0 70.0 88.0 89.5 Sucrose distearate 57.7 24.3 5.6 3.8 Methyl stearate 3.15 0.0 0.0 0.0 Potassium stearate 3.15 5.7 6.4 6.7 249

250 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS together with a small amount of solvent. After about six hours, the methyl ester has reacted completely to form a mixture of mono- and diesters of sucrose. An additional six hours is required for reaction between the diester of sucrose and the large excess of sucrose to effect essentially complete conversion to the sucrose monoester. The solvent is then re- moved and the product is separated from the unreacted sugar. Analytical data obtained during the course of a typical laboratory run are shown in Table 1. After the first three hours, most of the methyl stearate has been converted to sucrose ester. However, poly-substituted derivatives of sucrose exceed the quantity of monoester present. The figures in this table correspond closely to equimolar proportions of monoester and diester after three hours. On further heating the sucrose reacts with the diester to form more monoester. After six hours the weight ratio of mono- ester to poly-substituted esters calculated as diester is about 2.9 to 1. After twelve hours it is about 23.5 to 1. Diesters and more highly substituted esters of sugar are prepared under essentially the same conditions, using other ratios of sugar and methyl HHHHHHHH HHHHHHH HC-C-C-C- C- C-C-C-C =C-C-C-C-C-C-C-C-C--O -CH• HHHHHHHHH HHHHHHHHII I - , .... o o S•/c•'ose Monoo/ea[e H H•0H H OH OH H • HH HH HO-C-C-O-C-C-O i}-H H--}--O-C-C-O-C-C-OH I I HH HH HHHHHHH HHHHHHH I I HC-C-C-C-C-C-C-C-C=C- C-C-C-C-C-C-C-C-O-C-Ci• H-•IH HHHHHHHHH HHHHHHHH& •0 / [ween O-C-C-O-C-C-OH HHHHHH ./•N t-- HH HH HH HH HH HH HH HH HC-C-C-C-C-C• %'5 O-C-C- O-C-C-O-C- C- O-C-C- O-C-C- O-C-C-O-C-C-O- C-C-O H H IHHIH II I HH HH HH HH HH HH HH HH HCH HCH II I HHCH '•' Polyoxyethylene 41kylated Phenol HHHHHHHH HHHHHHH HC-C- C-C-C-C-C-C- C= C-C- C-C- C-C-C- C-C-O-CH e O O H O oO%H R•l/15•lOSe O/eate H H•OH H OH H OH OH H Figure 1.--Structure of sugar esters and other nonionics.