Zero-point Vibrational Contributions to the Optical Rotatory Power of

Zero-point Vibrational Contributions to the Optical Rotatory Power of Isotopically Dissymmetric Molcules. Wildon Fickett. J. Am. Chem. Soc. , 1952, 74...
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1,17-Heptadecanedioic Acid and 1,19-Nonadecanedioic Acid.-Reduction of tfle crude keto dibasic acids I1 and 111 by the Clemniensen methodg gave 1,17-heptadecanedioic acid showing n1.p. 118-118.5° with sintering at 117.5"~Oin S0.5% yield after two recrystallizations and 1,lY-nonadecanedioic acid showing m.p. 118-119°10 in 63% yield after two recrystallizations. The m.ps. of these acids when mixed with their related keto dibasic acids were lowcred in:rrkcdly; depressions of 8--10°were observed, '3) I

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where the q's represent the normal coordinates. We have supposed here that in any one mode of vibration the polarizability of only one group of each pair is appreciably affected by the vibration. 'The remaining second order terms are neglected for various reasons. The averaging process is carried out as before? and for groups with optical syirimetry, the result for g("' >, the expectation value of p"',is analogous to Kirkwood's corrected5


, 7 , 107 (1932).

Aug. 20, 1952

NOTES

4205

bond. Quantum mechanical calculations1° assign A calculation for 2-deuterobutane was also the positive sign to p' as does a consideration of the carried out, although as far as is known the optiknown sign of a' and the relative magnitudes of cally active compound has not been prepared. The a' and 0'. problem of internal conformation was treated in The optical rotation of the enantiomorph of a- terms of three isomers: two "bent" forms of equal deuteroethylbenzene shown was calculated from energy and one "straight" form, corresponding to Eq. (4). The angle C$ defining the internal con- the terminology of Szasz, Sheppard and Rank,14 formation is taken to be zero when the methyl who determined the equilibrium concentrations of group lies in the plane corresponding to the plane of the two forms from the temperature dependence symmetry of ethylbenzene, and to increase posi- of the infrared spectrum. The calculated optical tively as the phenyl group is rotated so as to increase rotation for the enantiomorph shown is [ a I z 5 ~ the distance from deuterium to the plane of the ring. +1.1" for a medium of refractive index 1.33, corresponding to the pure liquid. The author wishes to thank Professor J. G. Kirkwood for his help and advice throughout this investigation and Professor Verner Schomaker for a helpful discussion of the internal conformation of ethylbenzene. (14) G J. Szasz, N. Sheppard and D. H . Rank, J . Chem. P h y s . , 16, 705 (1948).

CONTRIBUTION KO.1620 FROM THE GATESA N D CRELLIN LABORATORIES OF CHEMISTRY CALIFORNIA INSTITUTE OF TECHNOLOGY 4, CALIFORNIA PASADENA

Some 10-Substituted Phenothiazines BY HENRYGILMAN, R . DAVID~YELSON AND JOHNF. CHAMPAIGNE, JR. RECEIVED MARCH15, 1952

There is a discrepancy in the literature concerning the melting point of 10-benzylphenothiazine. Desail reported that this compound, map.90.5-91°, was formed by heating a mixture of benzyldiphenylamine and sulfur a t 220' for 8 hours. Finzi2stated that this particular phenothiazine derivative was obtained by heating phenothiazine and benzyl chloride a t 140-145' for 2 hours. However, his product melted a t 130'. In connection with the cleavage of some alkoxy heterocycles by compounds containing the imino group, i t has been 1. (+) = m otherwise found3 that the reaction of 2-benzyloxyquinoline The calculated optical rotation is then [ C Y ] ~ ~ Dwith phenothiazine, in refluxing cumene, gave a +0.41" for a medium of refractive index 1.50, 90% yield of 2-hydroxyquinoline and a 34y0 yield corresponding to the pure liquid. The experi- of a product melting a t 91-92'. The latter commental value for the pure liquid enantiomorph pound analyzed for a benzylphenothiazine. A prepared by deuteride reduction of (-)-phenylrepetition3 of Finzi's preparation gave a small methylcarbinol is [ a ] 2 5-~0.30'. The relative amount of crystals, m.p. 132-134'. Therefore, the configuration of the carbinol is known.12 If the following procedure was attempted in order to predeuteride reduction is accompanied by inversion, pare the benzyl d e r i ~ a t i v e . ~A mixture of benzyl as is probably the case, then the (-)-a-deuterochloride and 10-lithiophenothiazine (prepared from ethylbenzene has a spatial configuration opposite phenothiazine and phenyllithium) in a benzeneto that for which the calculations were made, in ether solution and under a nitrogen atmosphere was agreement with the Fischer convention regarding stirred for one day a t room temperature and then absolute configuration, and consistent with the one hour a t reflux temperature. No pure product findings for 2,3-epoxybutane and 1,2-dichloro- has as yet been isolated. pr~pane.~,~~ Various 10-(dialkylaminoalky1)-phenothiazines have been prepared by refluxing in xylene (or simi(10) M. N. Adamov, Doklady Akad. N a u k . S.S.S.R., 6 2 , 461 (1948), C. A . , 43, 1264 (1949); J. 0. Hirshfelder, J . Chem. Phys.. 3 , lar solvent) a mixture of a dialkylaminoalkyl chlo555 (1935); J. G. Kirkwood, Physik. Z . , 83, 257 (1932). ride and phenothiazine in the presence of the (11) K. S. Pitzer and D . W. Scott, THISJOURNAL, 65, 803 (1943). The potential function for the internal conformation can be estimated roughly from the work of Pitzer and Scott on the xylenes." The ethyl group is assumed to have the staggered configuration and to be free to rotate relative to the ring until its hydrogens approach van der Waals contact with those of the ring. The simplified potential function is thus taken to be 1-(4) = 0 for - 30" L + L 30" V (+) = 0 for 150" L + L 210"

(12) W. A. Cowdry, E. D. Hughes, C. K . Ingold, S. Masterman and A. D . Scott, J . Chem. SOL.,1260 (1937); P . A. Levene and S. H. Harris, J . Biol. Chem., 113, 55 (1936); P . A. Levene and P. G . Stevens, ibid., 69, 471 (1930). 71, (13) W. Fickett, H . K. Garner and H . J. Lucas, THISJOURNAL, 5063 (1951).

(1) R. D. Desai, J . Indian Inst. Sci., 7 , 235 (1924) [C.A , , 19, 2645 (1925)l. (2) C. Finzi, Gasz. chim. ital,, 61, 175 (1932) [C. A , , 16, 4338 (1932) I. (3) H Gilman, I. Zarember and J. A Beel, THISJOURNAL, 74, 3177 (1952).