Molecular polarisability. The conformations as solutes of some phenyl- and chloro-derivatives of methane, ethane, and ethylene

Abstract

Polarity and polarisability measurements indicate that the apparent conformation of bis-(p-chlorophenyl)methane dissolved in carbon tetrachloride is that described by symmetrical or antisymmetrical rotations of the phenyl rings of ±34° from their position of coplanarity. For the DDT-like compounds 1,1,1-trichloro-2,2-diphenylethane and 1,1,1-trichloro-2,2-bis-(p-methylphenyl)ethane, the solution conformations appear to have the phenyl rings rotated antisymmetrically by –60° from coplanarity, while in 1,1,1,2-tetrachloro-2,2-diphenylethane they are symmetrically or antisymmetrically rotated by ±48°.

With the compounds 1,1-dichloro-2,2-diphenylethylene and 1,1,2,2-tetraphenylethylene, agreement between calculated and observed results occurs for symmetric or antisymmetric ring-rotations of ±40°, and ±35° or ±79° respectively.

For the remaining compounds, 1,1,2,2-tetrachloroethane, 1,1,2,2-tetrachloro-1,2-diphenylethane, 1,1,2,2-tetraphenylethane, and 1,2-dichloro-1,1,2,2-tetraphenylethane the data indicate the existence of trans–gauche mixtures in solution.