A method is developed for determining molecular conformations through analysis of experimental molar Cotton-Mouton constants in conjunction with known anisotropic magnetic susceptibilities and electric polarizabilities for structural groups. Molar Cotton-Mouton constants ( x 1OI6 e.m.u.), and derived interplanar angles, for molecules as solutes in carbon tetrachloride at 20°C are : biphenyl (+ 70, 0") ; 2,2'-bipyridyl (+ 76, 25") ; 9,9'-bianthryl (+ 160, 62") ; 9-phenylanthracene (+ 157, 70") ; 1-phenylnaphthalene (+ 79, 66") ; 1,3,5-triphenylbenzene (+ 169, 35").

No abstract

No abstract

Experimental dipole moments (1 03*p/C m) and molar Kerr constants [l 027703(mK2)/m5 V-2 mol-l] are reported for the following as solutes in cyclohexane at 25" : 2-formylpyrrole, 4.33, +76 ; 2-acetylpyrrole, 3.98, +50 ; and 2benzoylpyrrole, 4.06, +42. The results are analysed to provide information concerning the preferred conformations of these molecules.THE conformational preferences of heteroaromatic aldehydes and ketones are continuing to attract much attention. Various physical methods have been applied to the %substituted pyrroles (dipole m ~m e n t s , l -~ i.r.4-7 and n.m.r.8-14 spectra, dielectric relaxation 2, but some problems remain. It might reasonably be expected that

Dipole moments and molar Kerr constants ( ~1 0 " ) at 25 "C are reported for 1 -benzoylnaphthalene (3.01 D, -1 83) and 2-benzoylnaphthalene (3-1 4 D, +317) as solutes in carbon tetrachloride. Analysis of results yields information concerning the preferred conformations of these molecules.STUDIES of the conformations of aromatic aldehydes and ketones 1-5 are extended to the 1-and 2-benzoylnaphthalenes. Experimental dipole moments and molar Kerr constants for these molecules as solutes in carbon tetrachloride are reported and analysed. EXPERIMENTALSolutes.-The ketones were obtained in GU. 80% yield by Friedel-Crafts acylations using 1-or 2-naphthoyl chloride, aluminium chloride, and an excess of benzene. l-Benzoylnaphthalene had m.p. 75 "C (lit.,6 m.p. 76 "C),