Molecular polarizability of organic compounds and their complexes: LV. Molar volume and structure of some nitrogen compounds,their structural analogues,and some sterically hindered systems in solution

The molar volumes in solutions of a wide range of aliphatic and alicyclic amines, substituted acetanilides, 9- and 9,10-substituted anthracenes, and 1- and 1,8-substituted naphthalenes were estimated and discussed. Conformations of alkyl substituents in the aliphatic amines are similar to the conformations of the respective alkanes. Conformations (chair) of the molecules of alicyclic amines and cyclohexane are almost identical. In the molecules of acetanilides, the C(O)CH₃ group is conjugated with aromatic ring and is oriented toward the latter and toward the nitrogen of the amide group in the same manner as in acetophenone. A systematic decrease in the values of the molar volume increments of the substituents R in going from substituted benzene to substituted naphthalene and anthracene was revealed, which indicates the extension of the π-systems over the C-R bond. The orientation of 1,8-substituents relative to the naphthalene ring was found to be approximately orthogonal. A possibility to simplify the methods for determining the dipole moments and Kerr constants of compounds on the basis of their additive molar volumes was demonstrated.