Dipole Moments of the Salicylides

Abstract

THE electric dipole moments of the α- and β- salicylides (assumed to be disalicylides) were found to be 6.27 and 2.42 D. respectively in benzene solution. The solutions showed no change of polarization with time. The former, being definitely a disalicylide, may therefore be given the cis configuration (cf. Iβ above). Baker, Banks, Lyon and Mann¹ have shown that the geometry of this form of ring is variable, but the configuration (Iβ) is the most likely because the resonance energy will then be a maximum (cf. Marsden and Sutton²). The moment of the compound should then be approximately the resultant of the two lactone group moments (each of 4·12 D.²) at an angle θ, which can be calculated if the angles φ and ρ are known (see diagram). The angles Ph—C—O and Ph—O—C may each be assumed to lie between the limits of 109·5° and 120°. Since the rest of the geometry of the molecule is determined by the benzene rings, φ = 64·5—70middot;5°. ρ may be obtained from a molecular-orbital calculation³ and is found to be c. 27°. θ is therefore 82—86°, and the calculated moment is 6·2—6·0 D.