M. J. Murray

Infra‐Red Spectrum and Depolarization Factors of the Raman Lines of Spiropentane and the Raman and Infra‐Red Spectra of 1,1‐Dimethylcyclopropane,1 1‐Methylcyclobutene, and Methylenecyclobutane

The infra‐red absorptionspectrum in the region 700–4000 cm−1, both for the liquid and for the gas at various pressures, and precise values for the depolarization factors of the Raman lines of spiropentane are reported. Infra‐red and Raman frequencies, estimated relative intensities, and qualitative depolarization data are reported also for 1,1‐dimethylcyclopropane. Selection rules for the two hydrocarbons are discussed, and it is shown that the observed numbers of Raman frequencies are not inconsistent with the structures D 2d and C 2v for the spiropentane and 1,1‐dimethylcyclopropane, respectively. In addition, Raman and infra‐red data are included for the isomers, 1‐methylcyclobutene and methylenecyclobutane. Tentative assignments of the fundamentals are made for each of the four hydrocarbons.

Depolarization Measurements on Raman Lines by an Easy, Accurate Method

The depolarization factors of Raman lines are determined by a method in which a Polaroid disk, so oriented that it passes light whose electric vector is horizontal, is placed between the Raman tube and the lens which condenses the scattered light on the slit of the spectrograph. Two exposures of equal duration are made, one with the arc below, the other with it at the side, of the horizontal Raman tube. The ratio of the intensities in the two exposures (depolarization factor) is determined by comparison with the lines of seven argon spectra produced by argon light of known intensity ratios. Important advantages of the method are the comparatively short exposure times and the elimination of errors due to the polarization characteristics of the spectrograph. Results for the depolarization factors of Raman lines obtained from a mixture of benzene and carbon tetrachloride are given and comparison with previous data for these compounds is made.

Raman Spectra of Simple Ethers

Displacements, estimated intensities, and depolarization factors are listed for the main lines of diethyl ether, di‐n‐propyl ether, di‐isopropyl ether, di‐n‐butyl ether, di‐isobutyl ether, di‐n‐amyl ether, and di‐isoamyl ether. All the frequencies in the 2900 cm—1 region are polarized, except the one near 2970 cm—1 which is, without exception, highly depolarized.

Raman Spectra of Some Ethers Containing One or More Phenyl Groups

Raman frequencies, estimated intensities and depolarization factors are listed for n‐propylphenyl, n‐butylphenyl, ethylbenzyl, n‐butylbenzyl and dibenzyl ethers. Intense frequencies characteristic of monosubstituted benzenes whose values were constant in the five ethers are 618(5)0.8, 1001(10)0.1, 1029(7)0.3, 1156(4)0.8, 1176(4)0.8, 1588 and 1604 (6)0.7, 3058(9)0.3. Frequencies characteristic of the C–O–C bond may be those near 440, 900 and 1125 cm—1.

The Infra‐Red Absorption Spectrum of Methylphenylacetylene

The infra‐red spectrum of methylphenylacetylene between 500 and 2300 cm—1 has been measured with the aid of a prism spectrometer. The results are compared with the Raman spectrum of this compound, previously measured by the authors. The results are inconclusive as regards the assignment of the fundamental whose overtone, according to Badgers hypothesis, is responsible for the resonance splitting of the frequency near 2230 cm—1.