Raman Spectra of Hydrocarbons II. 2-Methyl-1-Heptene and 6-Methyl-1-Heptene

Abstract

Raman frequencies, relative intensities, and depolarization factors are listed for 2‐methyl‐1‐heptene and 6‐methyl‐1‐heptene. The spectrograms were made on Eastman 103‐J spectroscopic plates and the intensities were obtained with the aid of a Gaertner microdensitometer. The results are compared with data obtained in a previous study of 1‐octene, cis+trans 2‐octene, trans−3‐octene, and trans−4‐octene. Polarized lines at 1643 and 3000 and depolarized (or only slightly polarized) lines at 1294, 1416, and 3078 cm⁻¹ correspond to olefinic frequencies of the XHC=CH₂ group. When the group is XYC=CH₂, as for 2‐methyl‐1‐heptene, these frequencies appear at 1653, 2978, 1303, 1414, and 3077, the depolarization factors remaining essentially unaltered. Also a line of medium intensity was observed at 1674 for 2‐methyl‐1‐heptene; its appearance is probably due to an accidental resonance degeneracy. For the group XHC=CHY (trans), the 1416 and 3078 cm⁻¹ frequencies are absent and the three remaining frequencies occur near 1300, 1672, and 2998, the last two being polarized as for the other groups. Both of the methyl‐heptenes have more strong lines below 1200 cm⁻¹ than did the four octenes previously studied.