Molecular polarisability. Some chlorinated cyclohexanes

Abstract

Dipole moments and molar Kerr constants are reported for cis-, and trans-1.2-dichlorocyclohexane, 1 ,I ,2-trichlorocyclohexane, and the u-, y -, &-isomers of 1,2,3,4,5,6-hexachIorocyclohexane as solutes in carbon tetrachloride and for @-1,2,3,4,5,6-hexachlorocyclohexane as a solute in benzene. Our measurements suggest that the di-and tri-chloro-solutes exist as mixtures of chair and twist boat conformations in which the latter are predominant. For m-and y-hexachlorocyclohexane, the experimental observations can be explained by the presence of twist boatchair mixtures or by ' distorted ' forms, while for the 6-isomer. a ' distorted ' chair is indicated. @-Hexachlorocyclohexane appears to adopt the traditional chair arrangement with all chlorine atoms equatorially disposed. CONFORMATIONAL investigations of cyclohexane and itsderivatives involve consideration of chair and flexible ring arrangements. Hendrickson 1 has calculated that, for cyclohexane, the most energetically favourable conformation occurs when the carbon ring adopts the chair arrangement, while, for the flexible forms, the most stable is the twist (skew) boat form (see the Figure ). hexane ring to take a flexible conformation in preference to the normal chair. The existence of these conformational ' abnormalities ' has been discussed recently 3 by Robinson and Theobald. Here we apply the above considerations together with others based on polarities and polarisabilities to conf ormational problems presented by a series of chlorinated cyclohexanes. Chalr BoatTwist FIGURE Barton and Cookson,2 in a 1956 review, indicated that strong intramolecular forces may compel the cyclo-

Role of molecular geometry, valence charge distribution and vibrational modes in bioactivity of cyclodiene insecticides

“…They not only give a quantitative interpretation of the Raman spectra but also help in understanding the optical behaviour of insecticide molecules (Kirkwood, 1937;Partington, 1953;Pitzer, 1959). The polarizability, a reliable structural parameter, has been used to determine the bioactivity of chlorinated insecticides (Caderbank et al, 1970). Using the atom-dipole interaction model (Applequist et al, 1972), we have calculated the average polarizability of heptachlor to be equal to 30.117 Å 3 , whereas its experimental value (Caderbank and Pieren, 1976) is 30.…”

Optical anisotropies of methyl benzoate and diesters of benzenedicarboxylic acids as determined from the analysis of Kerr constants and depolarized light scattering measurements

“…However, the exact departure from planarity has not yet been well determined. 3 7 1 6 We have performed semiempirical 6.9…”