230 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table III Effect of Stability Additives on Gel Stability of Formula from US 4,154,816 Formulation Constants % Poloxamer 181 15.0 Cocamide MEA 3.0 Dibenzylidene Sorbitol 2.0 Triclosan 0.3 Aluminum Chlorohydrex 10.0 Stearic Acid, Triple Pressed 0.5 Fragrance 1.0 Formulation Variables Formula Number 29 30 31 32 33 34 35 % % % % % % % Propylene Glycol 28.7 -- -- 23.7 23.4 23.4 23.6 Butylene Glycol -- 68.2 -- -- -- Acetamide MEA -- -- 68.2 5.0 5.0 5.0 5.0 Magnesium Sulfate -- -- -- 0.3 -- -- Zinc Acetate .... 0.3 -- Methenamine ...... 0.1 Ethanol, Anhy. 39.5 -- 39.5 39.5 39.5 39.5 Stability Data: Days Until Completely Liquid @ 60øC 3 9-11 504 15 33 76 62 by solubility and aesthetic considerations. While magnesium sulfate and cocamide MEA apparently help stability, even together they do not improve stability enough to give a viable commercial product. Zinc acetate, methenamine and acetamide MEA alone or in combination appear capable of delivering a viable commercial product. The effect of these additives on antiperspirant efficacy will be the subject of a later paper. Table IV Effect of Acetamide MEA Concentration on Gel Stability Formulation Constants % Dibenzylidene Sorbitol 3.0 Steareth- 100 1.0 Butylene Glycol 20.0 Hexylene Glycol 10.0 Aluminum Chlorohydrex 15.0 Stearic Acid, Triple Pressed 0.5 Cyclomethicone 5.0 Formulation Variables Formula Number 36 37 % % Acetamide MEA 1.0 Ethanol, Anhy. 45.5 44.5 Stability Data: Days Until Completely Liquid @ 60 øC 3 4-6 @ 45øC 24 24 38 % 2.5 43.0 8 9O 39 % 5.0 40.5 20 367 40 7.5 38.0 59 367 41 % 10.0 35.5 169 367

CLEAR GEL ANTIPERSPIRANTS 231 CONCLUSION Solid antiperspirant gelled sticks can be prepared using DBS as the gelling agent and anhydrous alcohols and glycols as the solvent if suitable stabilizing agents are em- ployed. Zinc acetate, methenamine (hexamethylene tetramine), and acetamide MEA have been identified as suitable stabilizing agents. REFERENCES (1) E. L. Roehl and H. B. Tan, to Naarden International N.V., Solid antiperspirant composition and process for its preparation, US 4154816 (1979). (2) E. L. Roehl, to Naarden International N.V., Solid antiperspirant composition and process for its preparation, US 4346079 (1982). (3) P. Thomas and M. Sibi, Organogels obtained from the benzoic acetal of sorbitol, Cornpt. Rend., 183, 282-284 (1926). (4) J. K. Wolfe, R. M. Hann, and C. S. Hudson, 1,2,3,4-dibenzylidene-D-sorbitol,J. Am. Chem. Soc., 64, 1493-1497 (1942). (5) P. J. Van Der Laan and L. P. Van Der Mijll Dekker, The constitution of monobenzylidene-D-sor- bitol, Rec. Tray. Chim., 62, 824-826 (1943). (6) L. Vargha, Constitution of monobenzal-D-sorbitol. Remarks on a communication of P. J. Van Der Laan and L. P. Van Der Mijll Dekker, Ber., 77B, 608 (1944). (7) S. J. Angyal and J. V. Lawler, 1,3:2,4-dibenzylidene-D-sorbitol, J. Am. Chem. Soc., 66, 837-838 (1944). (8) S. Yamamoto, Sorbitol derivatives. IV. Purity of benzalsorbitol, ibid., 51, 114-115 (1948). (9) H. Hagiwara, Chemical structure of dibenzylidenesorbitol, ibid., 72, 929-930 (1952). (10) J. E. Courtois and P. Le Dizet, Preparation of L-xylose after periodic acid oxidation of o-benzylidene- sorbitol, Bull. Soc. Chim. Biol., 37, 287-289 (1955). (11) C. Ukita and S. Suzuki, Structure of 2,3,4,5-di-o-benzylidene-D-glucose derivatives, Yakugaku Zasshi, 81, 225-226 (1961). (12) T. G. Bonner, E. J. Bourne, and D. Lewis, 2,4:3,5-di-o-benzylidene-D-glucitol, Carbohyd. Res., 2, 421-425 (1966). (13) J. Kovar, Z. Burianec, and J. Jary, Solvolysis of benzylidene derivatives. III. Dibenzylidene deriva- tives of alditols, Collect. Czech. Chem. Commun., 32, 4099-4107 (1967). (14) T. G. Bonner, E. J. Bourne, P. J. V. Cleare, and D. Lewis, Kinetic and thermodynamic control in the formation of monoacetals from aldehydes and D-glucitol, J. Chem. Soc. B, 827-830 (1968). (15) D. J. Brecknell, R. M. Carman, J. J. Kirby, and L. T. Nicholas, Tri-o-benzylidene-D-Glucitol, Aust. J. Chem., 29, 1859-1863, (1976). (16) J. March, Advanced Organic Chemistry.' Reactions, Mechanisms, and Structure (McGraw-Hill, New York, 1968), pp 661-663. (17) T. J. Schamper, M. M. Perl, and J. D. Warren, to American Cyanamid Co., Acid stable dibenzyl monosorbitol acetal gels, US 4518582 (1985).