Volume 2

Recent advances in organic chemistry / by Alfred W. Stewart.

  • Stewart, Alfred W. (Alfred Walter), 1880-1947.
Date:
1931
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Recent advances in organic chemistry / by Alfred W. Stewart. Source: Wellcome Collection.

    357/458 (page 337)
    A further experiment of Schlenk and Thai served to clear up the whole matter, although at the first glance it seems rather to confuse the problem. When benzopinacone is suspended in benzene and treated with an alcoholic solution of sodium ethylate, the same sodium derivative is formed as is obtained by the action of sodium upon benzophenone. This appears to sup¬ port the Acree formula ; but the Acree formula will not agree with the boiling-point phenomena. How can these results all be brought into concord ? Schlenk and Thai suggested the simplest explanation by assuming that the coloured materials are really free radicles containing trivalent carbon atoms. On that assumption, the sodium derivative of benzophenone will have the formula \ry c6h/ xok and the production of this substance from benzopinacone and benzophenone can be expressed as shown below : (C6H5)2C—OH NaOEt (C6H5)2C—0—Na | + | + 2EtOH (C6H5)2C—OH NaOEt (C6H5)2C—0—Na j Dissociation. 4' i 2(C6H5)2C: 0 + Na2 = 2(C6H5)2C—0—Na This explanation is now accepted * as the most probable solution of the problem ; and these alkali derivatives of the diaryl ketones (and certain other substances to be mentioned later), which contain a trivalent carbon atom carrying the group —ONa in addition to two hydrocarbon radicles, are termed metal-ketyls. Although the direct action of sodium furnishes satisfactory yields of metal-ketyls from certain ketones, it gives poor results in other cases ; and with these last compounds a different method is generally employed. The most soluble of all the known metal-ketyls is potassium phenyl-diphenyl ketyl, C6H5 . C6H4-—C(OK)—C6H5. When an ethereal solution of this is mixed with dimethyl-pyrone, also dissolved in ether, a double * Compare, however, Schmidlin, Das Triphenylmethyl (1914), pp. 186 ff. VOL. II. Z