SOLUBILITY PARAMETERS IN COSMETIC FORMULATING 331 Table I (continued) CTFA Material Name Pyridine 10.30 Methoxypropanol 10.40' Isopropyl Lactate 10.42 Acetic Acid 10.42' Nonoxynol- 1 10.47' Hexyl Alcohol 10.50 Butoxyethanol 10.53 Butylparaben 10.57* Methyl Salicylate 10.62 Diacetone Alcohol 10.66 Triacetin 10.77 Methoxyethanol 10.80* Ethyl Lactate 10.84 Benzalphthalide 10.90* Benzaldehyde 11.00 D&C Red No. 22 (Eosin) 11.15' Butyl Alcohol 11.18 Isopropyl Alcohol 11.24 Nitrocellulose 11.25' PEG-8 11.34 Panthenol 11.39 PEG-6 11.47 Methyl Lactate 11.47 Benzoic Acid 11.50* PEG-5 11.54 PEG-4 11.61 Acetonitrile 11.70 Propyl Alcohol 11.73 Phenethyl Alcohol 11.79 Phenoxyethanol 11.87 Sorbic Acid 11.97 Methylparaben 11.98 Triethylene Glycol 12.21 Benzyl Alcohol 12.31 Hexylene Glycol 12.32* BHA 12.37 Alcohol 12.55 Adipic Acid 13.04 Butylene Glycol 13.20 Triethanolamine l 3.28 Propylene Carbonate 13.35' Dimethyl Sulfoxide 13.40 Diethylene Glycol 13.61 Propylene Glycol 14.00 Sodium Lauryl Sulfate 14.18' Methyl Alcohol 14.33 Ethylene Glycol 14.50 Lactic Acid 14.81 PABA 14.82' Ethanolamine 15.41' Sodium Capryl Sulfate 15.80* Glycerin 16.26 Ammonia 18.08 Water 23.40

332 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS most product properties, such as viscosity, volatility, lubricity, and tack, which give all cosmetics and toiletries their aesthetic appeal. It is evident that the limits of precision achieved by solubility technology offer consid- erable opportunity for refinement. Nevertheless, this field has progressed to the point where it now can yield major contributions to the advancement of the level of scientific formulation. Because solubility parameters are based on thermodynamic principles, they will serve to show what can be possible given adequate kinetic (mixing) treatment. Finally, the applicability of solubility parameters within the field of cosmetic chemistry has been demonstrated. Solubility parameters, unlike other measures of solubility, describe the physical size and strength of the intermolecular attractive fields. Therefore they lend themselves to mechanical explana.tions of intermolecular phenomena. As seen most recently in molecular biology, mechanical explanations can revolutionize a sci- entific field. Thus it is reasonable to expect many future refinements and computer applications of the solubility parameter applied to cosmetic chemistry. ACKNOWLEDGEMENTS The author would like to thank Dr. Paul Fehn, Mr. Paul Thau, and especially Dr. Frank J. Wright of Cosmair Inc. for their technical assistance and support, and Ms. Arlette Palo, of Cosmair Inc. and Dr. Richard Lovely of Yale University for their editorial assistance. I also wish to extend my appreciation to B. F. Goodrich Chemical Co. for permission to reproduce the chart labeled Figure 1. REFERENCES (1) (2) (3) (4) (5) (6) (7) (8) (9) (lO) (11) (12) (13) (14) (15) (16) D. Chandler, Chemistry, theory of liquids make gains. Chem. & Engr. News, April 11, 1983, p 30. J. H. Hildebrand and R. L. Scott, The Solubility of Nonelectrolytes, 3rd ed. (Reinhold Publ. Corp., New York, 1949). H. Burrel, The challenge of the solubility parameter concept,J. Paint Technol., 40, 197-208 (1968). C. M. Hansen, The three dimensional solubility parameter, J. Paint Technol., 39, 105 (1967). R. C. Nelson, Treatment of hydrogen bonding in predicting miscibility, J. Paint Technol., 42, 636 (1970). G. Lhoest, Use of physicochemical parameters to predict in vivo diffusion rate of an agent, Pharm. Acta Helv., 48, 549 (1973) (in French). P. A. Small, Some factors affecting the solubility of polymers, J. Appl. Chem., 3, 71 (1953). M. Nara, Dispersing pigments in cosmetics, Cosmetics & Toiletries, 94, 23 (January, 1979). S. A. Siddiqui, Studies of solvent dyeing, Textile Research Journal, 51, 527 (August, 1981). K. W. Harrison, "Solvents in Polymer Based Adhesives," in Adhesion, Vol. 13, K. W. Allen, Ed. (Applied Sci. PUN., Barking, England), Chapter 9. R. Tijssen, H. Billiet, and P. Schoenmakers, Use of the solubility parameter for predicting selectivity and retention in chromatography. J. Chromatogr., 122, 185 (1976). A. F. Barton, Handbook of Solubility Parameters and Other Cohesion Parameters (CRC Press, Boca Raton, 1983). P. Alessi, I. Kikic, and G. Torriano, Correlation of hydrocarbon activity coefficients with solubility parameters, J. Chromatogr., 106, 17, (1975). B. Alder, 1985 ACS Award in Experimental Chemistry of Liquids---Computer Simulations of Molecular Liquid Viscosity. S. E. Friberg, 1985 ACS Award in Colloid & Surface Chemistry--Non-Aqueous Lyotropic Liquid Crystals and Foams. J. S. Fritz, 1985 ACS Award in Analytical Chemistry--Non-Aqueous Acid-Base and Ion Exchange Chemistry.