ESTERIFICATION OF HYDROXY COMPOUNDS 251 Table I % Reaction by Acid Value Reduction Reaction With Stearic Acid (1:1) at 195øC at Atmospheric Pressure for Non-Silicone Primary Hydroxy Compounds Hours at reaction condition Hydroxy reactant 0 1 2 3 4 5 Stearyl alcohol 0 43.3 74.0 82.4 86.7 91.5 Guerbet alcohol 0 43.9 72.2 80.5 86.3 92.0 Polyoxyethylene glycol 350 (methyl capped) 0 39.2 61.6 75.3 84.5 93.7 Polyoxyethylene glycol 3350 0 33.1 50.7 67.0 75.5 81.5 Designation Equiv. molecular weight % Rxn 3 hr Stearyl stearate 464 82.4 Guerbet stearate 564 80.5 Methoxy PEG 350 stearate 614 75.3 PEG 3350 distearate 1939 67.0 Table II % Reaction by Acid Value Reduction Reaction With Stearic Acid (1:1) at 195øC at Atmospheric Pressure for Non-Silicone Secondary Hydroxy Compounds Hours at reaction condition Hydroxy reactant 0 1 2 3 4 5 Polyoxypropylene glycol 4000 0 31.4 48.4 Polyoxypropylene glycol 2000 0 34.0 49.9 Polyoxypropylene glycol 1000 0 36.9 52.6 60.3 67.3 71.0 62.0 68.8 73.9 65.0 72.0 77.0 Designation Equiv. molecular weight % Rxn 3 hr PPG 4000 Distearate 2264 60.3 PPG 2000 Distearate 1764 62.0 PPG 1000 Distearate 764 65.0 Acid value is defined as the number of milligrams of potassium hydroxide equivalent to the acid content of I gram of sample. The method is a simple titration of the ester sample with a standardized base to a pink color using phenolphthalein solution. A 50/50 blend of ethanol/water was the solvent chosen. HYDROXYL VALUE The hydroxyl-containing materials were subjected to a hydroxyl value determination, and an equivalent molecular weight was established for each of them prior to reaction. Hydroxyl value is defined as the number of milligrams of potassium hydroxide equiv- alent to the hydroxyl content of I gram of sample. The classical wet method was used in which the hydroxyl-containing materials are reacted with phthalic anhydride. The details of the procedure can be found in ASTM E 326 and D 1638. ß

252 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table III % Reaction by Acid Value Reduction Reaction With Stearic Acid (1:1) at 195øC at Atmospheric Pressure for Silicone Primary Hydroxy Compounds Hours at reaction condition Hydroxy reactant 0 1 2 3 4 5 Dimethicone copolyol (comb) 0 43.9 72.2 Dimethicone copolyol (terminal) 0 38.0 66.4 Dimethiconol 0 36.6 58.6 Designation 81.0 87.5 94.0 78.0 85.0 91.0 68.9 76.4 80.5 Equiv. molecular weight % Rxn 3 hr Dimethicone copolyol stearate (comb) Dimethicone copolyol stearate (terminal) Dimethiconol distearate 1264 81.0 1389 78.0 2264 68.9 SAPONIFICATION VALUE The final ester was subjected to saponification value determination to verify that the expected ester was in fact produced. The method chosen was AOCS Method TI la-64 T. The following graphs, Figures 1-3, show the reaction progress as a function of time at 100, 80 60 40 20 -'- Stearyl Alcohol •- PEG 3350 --x- Guerbet •- Me Peg I 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 Time (hours) Figure 1. Percent esterification reaction for non-silicone esters.