INFRARED C--H FREQUENCIES, THEIR SIGNIFICANCE 285 dry ice in order to resolidify it. The same behavior at a higher transition temperature can be demonstrated for the case of I G wax Z, shown in Fig. 2. That the doublet disappears not only on melting but also upon dis- solving is shown in Fig. 3 for Utah wax where the solution in iso- octane shows but the single band. The most satisfying explanation of what he terms "infrared di- chroism" has just been advanced by Krimm (6) who pointed out that the two components arise from in-phase/out-of-phase rock- ing of CH.o groups on adjacent chains. The importance of infrared measurements and observation in the cosmetic industry has been pointed out repeatedly (7, 8). We have studied a number of natural and synthetic products (Table 1) particularly with reference to the doublet CH2-rockingeffect. From the above remarks we believe that this phenomenon permits a statement as to the nature, i.e., linearity of the hydrocarbon por- tion of the solid material under ob- servation and constitutes a useful qualitative analytical parameter. 13 •, 15 Wavelength Figure 3.--Absorption spectrum of Utah wax: -- iso-octane• solvent -- Utah Wax in iso-octane ---- Utah Wax, solid, room temp. .... Utah Wax, molten, 120 ø . It should be pointed out that glyceryl monostearate, and both Bayberry and Japan wax, which are mainly glycerides, do not show the doublet. A possible explanation could be that the glyceryl portion of the molecules prevents them from packing close enough for the CH2 in adjacent chains to show any in-phase/out-of-phase rocking. BIBLIOGRAPHY (1) Thompson, H. W., and Torkington, P., Proc. Roy. Soc., A184, 3 (1945). (2) Elliot, E. J., Ambrose, E. J., and Temple, R. B.,'•'. Chem. Phys., 16, 877 (1948). (3) Simanouti, T., ibid., 17, 734 (1949).
286 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS (4) Brown, J. K., Sheppard, N., and Simpson, D. M., Discussions Faraday Sot., 9, 26! (1950). (5) Sutherland, G. B. B. M., Ibid., 9, 274 (1950). (6) Krimm, S., 5 t. Chern. Phys., 22, 567 (1954). (7) Bernstein, R. B., J. Soc. CosMY. TiC C•M., 3, 265 (1952). (8) Hausdorff, H. H., Ibid., 4, 251 (1953). RECENT PROGRESS IN THE CHEMISTRY OF DI- SULFIDES* By NORMAN A. ROSENTHAL and GERALD OSTER• Institute for Polymer Research, Polytechnic Institute of Brooklyn, Brooklyn, N.Y. 1. INTRODUCTION Ti•E WIDESPREAD occurrence in nature of compounds containing sulf- hydryl and disulfide groups forces one to accept these substances as being essential in the chemistry of living processes. The important role of nat- urally occurring sulfhydryl compounds such as glutathione and cysteine in the oxidative processes taking place in living cells was emphasized by Hopkins and his co-workers at Cambridge University many years ago. The role of sulfur in intermediate metabolism and its implications to medicine have been ably summarized in the recent book of duVigneaud (1). It has even been suggested that sulfur-containing compounds may play a critical role in photosynthesis (2) and in vision (3). The large body of research on the chemistry of proteins carried out over the past half century has established that the disulfide linkage is an im- portant structural element in proteins. The liberation of sulfhydryl groups when proteins are denatured may indicate that disulfide groups are holding the protein-structure together and that they are ruptured on denaturation (4). The detailed studies of Sanger (5) have shown that the polypeptide chains of insulin are held together by disulfide bonds. Keratin is particu- larly rich in disulfide bonds and, for the case of wool and hair, cystine is found in greater abundance than any other single amino acid. Most of the chemical treatment of wool and hair is concerned with the rupture and re- formation of the disulfide bond. It is obvious, therefore, that any rationali- zation of the process employed, for example, in permanent hair waving must require a complete understanding of the chemistry of the disulfide link- age. * Presented at the May 1• 1954, Meeting, New York City. t Taken in part from the thesis submitted by Norman A. Rosenthal in partial fulfillment for the requirements for the degree of Doctor of Philosophy.
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INFRARED C--H FREQUENCIES, THEIR SIGNIFICANCE 285 dry ice in order to resolidify it. The same behavior at a higher transition temperature can be demonstrated for the case of I G wax Z, shown in Fig. 2. That the doublet disappears not only on melting but also upon dis- solving is shown in Fig. 3 for Utah wax where the solution in iso- octane shows but the single band. The most satisfying explanation of what he terms "infrared di- chroism" has just been advanced by Krimm (6) who pointed out that the two components arise from in-phase/out-of-phase rock- ing of CH.o groups on adjacent chains. The importance of infrared measurements and observation in the cosmetic industry has been pointed out repeatedly (7, 8). We have studied a number of natural and synthetic products (Table 1) particularly with reference to the doublet CH2-rockingeffect. From the above remarks we believe that this phenomenon permits a statement as to the nature, i.e., linearity of the hydrocarbon por- tion of the solid material under ob- servation and constitutes a useful qualitative analytical parameter. 13 •, 15 Wavelength Figure 3.--Absorption spectrum of Utah wax: -- iso-octane• solvent -- Utah Wax in iso-octane ---- Utah Wax, solid, room temp. .... Utah Wax, molten, 120 ø . It should be pointed out that glyceryl monostearate, and both Bayberry and Japan wax, which are mainly glycerides, do not show the doublet. A possible explanation could be that the glyceryl portion of the molecules prevents them from packing close enough for the CH2 in adjacent chains to show any in-phase/out-of-phase rocking. BIBLIOGRAPHY (1) Thompson, H. W., and Torkington, P., Proc. Roy. Soc., A184, 3 (1945). (2) Elliot, E. J., Ambrose, E. J., and Temple, R. B.,'•'. Chem. Phys., 16, 877 (1948). (3) Simanouti, T., ibid., 17, 734 (1949).
286 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS (4) Brown, J. K., Sheppard, N., and Simpson, D. M., Discussions Faraday Sot., 9, 26! (1950). (5) Sutherland, G. B. B. M., Ibid., 9, 274 (1950). (6) Krimm, S., 5 t. Chern. Phys., 22, 567 (1954). (7) Bernstein, R. B., J. Soc. CosMY. TiC C•M., 3, 265 (1952). (8) Hausdorff, H. H., Ibid., 4, 251 (1953). RECENT PROGRESS IN THE CHEMISTRY OF DI- SULFIDES* By NORMAN A. ROSENTHAL and GERALD OSTER• Institute for Polymer Research, Polytechnic Institute of Brooklyn, Brooklyn, N.Y. 1. INTRODUCTION Ti•E WIDESPREAD occurrence in nature of compounds containing sulf- hydryl and disulfide groups forces one to accept these substances as being essential in the chemistry of living processes. The important role of nat- urally occurring sulfhydryl compounds such as glutathione and cysteine in the oxidative processes taking place in living cells was emphasized by Hopkins and his co-workers at Cambridge University many years ago. The role of sulfur in intermediate metabolism and its implications to medicine have been ably summarized in the recent book of duVigneaud (1). It has even been suggested that sulfur-containing compounds may play a critical role in photosynthesis (2) and in vision (3). The large body of research on the chemistry of proteins carried out over the past half century has established that the disulfide linkage is an im- portant structural element in proteins. The liberation of sulfhydryl groups when proteins are denatured may indicate that disulfide groups are holding the protein-structure together and that they are ruptured on denaturation (4). The detailed studies of Sanger (5) have shown that the polypeptide chains of insulin are held together by disulfide bonds. Keratin is particu- larly rich in disulfide bonds and, for the case of wool and hair, cystine is found in greater abundance than any other single amino acid. Most of the chemical treatment of wool and hair is concerned with the rupture and re- formation of the disulfide bond. It is obvious, therefore, that any rationali- zation of the process employed, for example, in permanent hair waving must require a complete understanding of the chemistry of the disulfide link- age. * Presented at the May 1• 1954, Meeting, New York City. t Taken in part from the thesis submitted by Norman A. Rosenthal in partial fulfillment for the requirements for the degree of Doctor of Philosophy.

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