Dynamic Molecular Behavior and Cluster Structure of Octanoic Acid in Its Liquid and CCl<sub>4</sub> Solution
- 1 Department of Chemistry, School of Science, Kitasato University, Sagamihara, Japan.
- 2 Department of Chemistry, School of Science, Kitasato University, Sagamihara, Japan.
- 3 Department of Chemistry, School of Science, Kitasato University, Sagamihara, Japan.
- 4 Department of Chemistry, School of Science, Kitasato University, Sagamihara, Japan.
Abstract
Fatty acids such as oleic and stearic acids having a long hydrocarbon chain are known to exist as dimers in their melt and even in a non-polar solvent. In their melt the dimers arrange longitudinally and alternately to form clusters which resemble a smectic liquid crystal. The clusters determine the liquid properties of the fatty acids such as density, viscosity and fluidity. Then, do the dimers of fatty acid having a moderate-length hydrocarbon chain construct such the clusters? In the present study the dynamic molecular behavior and assembly structure of octanoic acid in its melt and also in CCl4 solution have been investigated by the X-ray diffraction, near infrared spectroscopy, 1 H-NMR chemical shift, self-diffusion coefficient and 13 C-NMR spin-lattice relaxation time measurements. From these results it has been revealed that the clusters of octanoic acid exist in its melt and also in CCl4 and that the clusters in the melt disintegrate with an increase in temperature. The dissociation profile of dimers of octanoic acid into monomers in CCl 4 also has been clarified.
- M. Iwahashi, M. Suzuki, M. A. Czarnecki and Y. Ozaki, “Near-IR Molar Absorption Coefficient for the OH Stretching Mode of cis-9-Octadecenoic Acid and Disso ciation of the Acid Dimers in the Pure Liquid State,” Journal of the Chemical Society, Faraday Transactions, Vol. 91, No. 4, 1995, pp. 697-701. doi:10.1039/ft9959100697
- M. Iwahashi, Y. Kasahara, H. Minami, H. Matsuzawa, M. Suzuki and Y. Ozaki, “Molecular Behaviors of n-Fatty Acids in Liquid State,” Journal of Oleo Science, Vol. 51, No. 3, 2002, pp. 157-164. doi:10.5650/jos.51.157
- M. Iwahashi, Y. Kasahara, H. Matsuzawa, K. Yagi, H. Nomura, H. Terauchi, Y. Ozaki and M. Suzuki, “Self Diffusion, Dynamical Molecular Conformation and Liq uid Structures of n-Saturated and Unsaturated Fatty Ac ids,” The Journal of Physical Chemistry B, Vol. 104, No. 26, 2000, pp. 6186-6194. doi:10.1021/jp000610l
- T. R. Lomer, “The Crystal and Molecular Structure of Lauric Acid (Form A1),” Acta Crystallographica, Vol. 16, 1963, pp. 984-988. doi:10.1107/S0365110X63002632
- M. Goto and E. Ashida, “The Crystal Structure of the A-Super Form of Lauric Acid,” Bulletin of the Chemical Society of Japan, Vol. 51, No. 1, 1978, pp. 70-74. doi:10.1246/bcsj.51.70
- F. Kaneko, K. Yamazaki, K. Kitagawa, T. Kikyo, M. Kobayashi, Y. Kitagawa, Y. Matsuura, K. Sato and M. Suzuki, “Structure and Crystallization Behavior of the β Phase of Oleic Acid,” The Journal of Physical Chemistry B, Vol. 101, No. 10, 1997, pp. 1803-1809. doi:10.1021/jp963400a
- M. Iwahashi, A. Umehara, K. Wakisaka, Y. Kasahara, H. Minami, H. Matsuzawa, H. Shinzawa, Y. Ozaki and M. Suzuki, “Effect of Cholesterol and Other Additives on Viscosity, Self-Diffusion Coefficient, and Intramolecular Movements of Oleic Acid,” The Journal of Physical Chemistry B, Vol. 111, No. 4, 2007, pp. 740-747. doi:10.1021/jp0619538
- T. C. Farrar and E. D. Becker, “Pulse and Fourier Transform NMR,” Academic Press, New York, 1971.
- H. G. Hertz, “The Problem of Intramolecular Rotation in Liquids and Nuclear Magnetic Relaxation,” Progress in Nuclear Magnetic Resonance Spectroscopy, Vol. 3, 1967, pp. 159-164. doi:10.1016/0079-6565(67)80015-3
- M. Iwahashi, N. Hachiya, Y. Hayashi, H. Matsuzawa, M. Suzuki, Y. Fujimoto and Y. Ozaki, “Dissociation of Dimeric cis-9-Octadecenoic Acid in Its Pure Liquid State as Observed by Near-Infrared Spectroscopic Measure ment,” The Journal of Physical Chemistry, Vol. 97, No. 13, 1993, pp. 3129-3133. doi:10.1021/j100115a011