Molecular polarisability. The conformations of 1-acetyl- and 1,5-diacetyl-naphthalenes and -anthracenes

Abstract

Dipole moments and molar Kerr constants (× 10¹²) at 25° are reported for the following as solutes in carbon tetrachloride: 1-chloroanthracene (1·43 D, +229), 1-cyanoanthracene (4·14 D, +870), 1-acetylnaphthalene (2·89 D, +203), 1-acetylanthracene (2·67 D, +243), 1,5-diacetylnaphthalene (2·13 D, –379), and 1,5-diacetylanthracene (2·13 D, –500). For 1-acetylnaphthalene and 1-acetylanthracene, the experimental results are consistent with effective conformational angles of 46 and 42°, respectively, between the C–CO–C plane and the plane of the aromatic ring. The two diacetyl compounds have been considered as mixtures of cis- and trans-conformations in which the C–CO–C planes are inclined at 45° to the aromatic plane.