308 JOURNAL OF COSMETIC SCIENCE 18: Yield: 60% b.p. 63.5øC/2 mm Hg nD 20 = 1.4432 •H NMR (8): 0.16 (s, 6H, -Si(CH3)2-), 0.95 (d, J -- 6.6 Hz, 6H, -CH(CH3)2) , 1.05 (t, J = 8.4 Hz, 2H, -CH2CH20-), 1.80 (m, 1H, -CH(CH3)2) , 2.01 (s, 3H, -C(O)CH3), 2.08 (d, j = 6.6 Hz, -CH2C=), 4.20 (t, J = 8.4 Hz, -CH2CH20-) IR (cm •): 2176 (s), 1740 (s), 1240 (s), 1040 (s), 824 (s). Anal. Calcd. for C12H2202Si: C, 63.67 H, 9.79. Found: C, 63.75 H, 9.85. 19: Yield 91% b.p. 67øC/2 mm Hg nD 2ø -- 1.4440, •H NMR (8): 0.13 (s, 6H, -Si(CH3)2-) , 0.88 (d, J -- 6.8 Hz, 6H, -CH(CH3)2, 1.04 (t, J = 8.4 Hz, 2H, -CH2CH20-), 1.61 (m, 1H, -CH(CH3)2) , 1.98 (ddd, j = 7.3, 6.9 and 1.3 Hz, 2H, -CH2CH=CH-), 1.99 (s, 3H, -C(O)CH•), 4.14 (t, j = 8.4 Hz, -CH2CH20-), 5.44 (dr, J = 14.2 and 1.3 Hz, 1H, -CH2CH=CH-), 6.33 (dr, J = 14.2 and 7.3 Hz, 1H, -CH2CH=CH-) IR (cm •): 1740 (s), 1608 (m), 1240 (s), 1048 (s), 712 (m). Anal. Calcd. for C•2H2402Si: C, 63.10 H, 10.59. Found: C, 63.01 H, 10.72. ACKNOWLEDGMENTS We thank Prof. J. G6ra for help in the odor evaluation of our compounds. REFERENCES (1) (2) (3) (4) (5) (6) (7) (8) (9) (lO) (11) (12) (13) (14) (15) C. Wawrzeficzyk, Z. Przepi6rka, and A. Zab2a, Insect growth regulators. Part IX. Syntheses of aryl 3,7-dimethyl-4-octen-l-yl ethers, Po/. J. Chem., 55, 819 (1981). R. Obara, T. Olejniczak, and C. Wawrzeficzyk, Odoriferous derivatives of (E)-3,7,7-trimethyl-4-octen- 1-ol and its 7-sila analogue, J. Soc Cosmet. Chem., 46, 321-328 (1995). R. Tacke, M. Strecker, G. Lambrecht, U. Moser, E. Mutschler, Bioisosteric C/Si exchange in para- sympatholytics of the pridinol type sila drugs, Arch. Pharm., 317, 207 (1984). R. Tacke, M. Strecker, G. Lambrecht, U. Moser, and E. Mutschler, (2-Aminoethyl) cycloalkylphenyl- silanole: Bioisosterer CSi--Austausch bei parasympatholytika vom typ des trihexylphenidyls, Lycrim- ins und Procyclidins, Liebigs Ann. Chem., 922-930 (1983). S. McN. Siebruth, S. Y. Lin, J. F. Engel, J. A. Greenblatt, S. E. Burkart, and D. W. Gammon, "Silane Analogues of MTI-800: Biology and Chemistry," in Recent Advances in the Chemistry of lmect Control J. Crombie, Ed. (Royal Society of Chemistry, Cambridge, 1989), pp. 142-150. I. Ujvary, A. Kis-Tamas, L. Varjes, and L. Nowak, Syntheses of silicon-containing juvenile hormone analogues, Acta Chimica Hungarica, 113, 165-175 (1983). T. Olejniczak, S. Lakota, A. Raszka, and C. Wawrzeficzyk, "Synthesis and Biological Activity of Some Sila-Juvenoids," in Insects: Chemical, Physiological and Environmental Aspects, D. Konopifiska, Ed., 1985, pp. 271-275. R. Munstedt and U. Wannagat, Sila-Riechstoffe und Riechstoffe-Isostere, Ein neur Weg zu Sila-[3- Jonon, Monatsh, 116, 693-700 (1985). R. Munstedt and U. Wannagat, ot-Formylopropenylsilane als Modellsubstanzen flit b-cyclocitral, Liebigs Ann. Chem., 944-945 (1985). U. Wannagat, R. Munstedt, and U. Horder, Sila [3-jonon und verwandte Verbindungen, Liebigs Ann. Chem., 950-958 (1985). E. Vedejs and P. L. Fuchs, Inversion of acyclic olefins by the phosphorus betaine method: Scope and limitations, J. Am. Chem. So• , 95, 822-825 (1973). L. Birkofer and T. Ktihn, Einfache Synthesen von symmetrischen his (trimethylsilyl)-ethen, Chem. Ber., 111, 3119-3123 (1978). H.N. Miller, K.W. Greenlee, J. M. Derlet, and C.E. BooM, Mono- and dialkylacetylenes from vicinal dihalides and sodium amide in liquid ammonia, J, Org. Chem., 19, 1882-1888 (1954). P.M. Milller and D. Lamparsky, Perfurmes--Art, Science and Technology (Elsevier Applied Science, London, 1991), pp. 278-286. L. Bateman, J. I. Cunneen, and E. S. Waight, Geranidenes the decomposition of 2,6-dimethylhept- 5-en-2-ol and some derivatives thereof, J. Chem. Soc., 1714-1718 (1952).

j. Cosmet. Sci., 49, 309-320 (September/October 1998) Photodegradation of human hair S. RATNAPANDIAN, S. B. WARNER, and Y. K. KAMATH, Textile Sciences Department, University of Massachusetts, Dartmouth, MA (S.R., S.B.W.), and TRI/Princeton, Princeton, NJ (Y. K. K.). Accepted for publication August 31, 1998. Synopsis The role of moisture in photolysis of hair was investigated in this research. Melanin-free Piedmont hair was exposed to simulated sunlight at different humidity levels. Changes in wet mechanical properties, swelling behavior, and IR spectrum were used to determine the degree of damage. Weathering damages hair under all conditions of relative humidity during exposure, with exposure at 30% RH causing the least damage. A free-radical mechanism is used to explain the photolysis process. INTRODUCTION Hair is constantly subjected to repeated environmental assaults, commonly termed "weathering." Weathering occurs over a period of time, and the effects can be easily observed on long hair, with tip ends being more damaged than root ends. Hair light- ening and dullness, weak and brittle tips, split ends, and an overall rough feel are a few of the obvious characteristics of damaged hair (1,2). Damage to hair causes a reduction in tensile and fatigue properties (3). According to Robbins and Bahl (4) and Speakman et al. (5), the reduction is largely attributed to chemical damage to the protein chains, especially the S-S covalent crosslinks in cystine. The loss of crosslinks, in photochemical damage, alone will result in increased solvent swelling, although Wolfram (6) disagrees. He argues that crosslinking between amino acid residues would occur on irradiation and that these new crosslinks would limit solvent swelling in the case of keratin fibers. According to the hair photolysis mechanism proposed by Tolgyesi (1), cystine, tyrosine, phenylalanine, and tryptophan residues absorb UV radiation, resulting in the formation of free radicals. Homolytic scission of disulfide bonds occurs. Melanin, the natural coloring matter in hair, provides partial protection to the hair fiber. It acts in a sacrificial manner, resulting in the lightening of hair color. Tolgyesi (1) explained that melanin, by its comprehensive system of double bonds and conjugated carbonyl groups, protects hair by scavenging free radicals generated by exposure to light. Wei (7) furthered the free-radical mechanism by showing that, all other factors being equal, the extent of 309