Studies on the Dipole Moments of Acenaphthene and its Derivatives

The dipole moment of acenaphthene (I) was measured in the gaseous phase as 0.93D. Measurement in benzene solution at 25°C gave the following moment values: acenaphthene (I) 0.85D; 5-chloroacenaphthene (II) 2.50D ; and 5,6-dichloroacenaphthene (III) 3.85D. By the comparison with the moments of naphthalene derivatives it was shown that the moments of (II) and (III) are approximately equal to the sums of the moment of (I) and the moments arising from one and two C–Cl bonds, respectively.