Raman spectra of aliphatic chlorine compounds: I. Chloroethanes and chloropropanes

In the present paper, No. I of a series comprising a comparative study of the Raman spectra of a great number of different kinds of aliphatic chlorine compounds, chloroethanes and chloropropanes are considered. Thirteen chloropropanes have been prepared and their Raman spectra determined. For twenty‐six of the twenty‐nine possible derivatives, frequency data therefore are now available. Quantitative polarization measurements have been carried out for the thirteen compounds and for six other chloropropanes for which only frequencies had been published. For the chloroethanes, chloropropanes, and a number of chlorobutanes. “specific group frequencies” have been inferred for the following groups: CH3CH2Cl, CHCl, CHCl2, CH2, and CCl3. The constancy of these characteristic frequencies is retained in compounds containing more of these groups, either similar or different. The influence which the degree of substitution of chlorine for hydrogen exerts on the numerical value of a specific group frequency gives indications as to the number of chlorine atoms present in the rest of the molecule. Regularities have been observed in the trend of the carbon‐carbon chain and carbon‐chlorine vibrational frequencies with the degree of substitution. No distinct indications of the presence of rotational isomerism in the compounds studied have been found.