INFRARED STUDY OF N-ALKANES IN CCL4, CDCL3 CCL4, AND CDCL3 0.5-PERCENT SOLUTIONS/

Three factors appear to affect n-alkane molecular vibrations in CHCl3/ CCl4 solutions. These are: (1) Physical restriction of the nuCH3 and n uCH2 vibrations by solvent molecules. (2) Intermolecular hydrogen bond ing between n-alkane protons and the free pair of electrons on Cl atom s of either CCl4 or CDCl3. The positively charged alkane protons arise during the dipole moment changes, deltaP/deltaQ, occurring during a f ull cycle of the nuCH3 and nuCH2 modes. (3) The physical restriction o f solvent molecules, which is greater in the case of CDCl3 than in the case of CCl4 due to a high degree of CDCl3 orientation about n-alkane molecules due to repulsion of the C-D of CDCl3 by the n-alkane nuCH3 and nuCH2 protons, which allows stronger C-D:Cl bonds to be formed bet ween solute and solvent.