The few reports in the literature describing attempts a t the direct halogenation of indole in the pyrrole ring, with bromine, chlorine, or iodine (1-3), indicate that a vigorous reaction does indeed occur. However, only in the case of iodination, and then only in

differences in chemical shift of the signal for the a: proton in indole and substituted indoles occur when spectra are obtained in non-polar and polar solvents. I n contrast, using polar and non-polar solvents, only small differences are observed in the chemical shift of the signal for the 6 proton in indoles. The utility of the solvent effect on the chemical shift to distinguish between CY and substitutioil of the indole nucleus is pointed out.

A preliminary X-ray exainination of synz-diplienyl urea and sym-diphenyl thiourea has been carried out a s part of the prograin t o study the crystal and n~olecular structures of the derivatives of urea and thiourea. These two derivatives are formed by a syrnrnetrical substitution of one hydrogen by a benzene ring on each of the two nitrogen atoins of urea and thiourea. From the exaillination of the ultraviolet absorption spectra of the substituted ureas, Picard and R4cKay (2) pointed out that some double bond character Canadian Jourl~al of Chemistry. Volume 42 (1964) Can. J. Chem. Downloaded from www.nrcresearchpress.com by 54.245.13.81 on 05/12/18For personal use only.

Doubling of nuclear magnetic resonances of certain mixed phosphorus esters has been observed and has been attributed t o the presence of rotational conformers occupying "up" and "down" orientations of the ester moieties. Treatment of these esters with uranyl nitrate results in the expected resonances, although chemically shifted. This is believed t o be due to the "freezing" of rotational conformers by complex formation. Dependence of the observed resonances upon temperature supports this hypothesis. There appears to be some steric control over the relative population of the contributing conformers.

3-Ethylthioindole has been prepared by Fischer cyclizatio~~ of tlle condensation product of phenylhydrazine and ethylthioacetaldehyde diethyl acetal, and also by a route involving thc reaction of ethyl iodide with the sodiunx borohydride reduction product of 1,2-dithiolo[4,Y-!]indole-3-(4H)-thione. The last-named compound was obtained by reaction of 2-carbcthosyindosyl with phosphorns pentasulfide.