The optically active spiro-5:5-Dihydantoins

The first substance to be obtained, showing optical activity in the amorphous state but containing no asymmetric atom in the molecule, was the 1-methyl cyclo hexylideneacetic acid, CH 3 /CCH 2 . CH 2 C = CH H/ CH 2 . CH 2 / COOH of Perkin and Pope, the resolution of the synthetic material being effected by Perkin, Pope and Wallach. In a later paper Perkin and Pope showed that the optical activity persists in a remarkable way throughout a series of reactions. At that time it was recognised that certain types of carbospiranes should be similarly resolvable into optically active components, but the first case of this kind to be realised was that of the keto-dilactone of benzophenone- 2 :4 :2 ': 4'-tetracarboxylic acid prepared by Mills /CO_O COOH/¯¯\__|__/¯¯ COOH ; C \__/ \__/ |O-CO/ the resolution was effected by Mills and Nodder. The work of Mills and Nodder established the stereochemical principle involved, but the compounds used in this and similar later investigations are of complex constitution and do not lend themselves readily to the study of the effects of substitution or tautomeric change on the optical activity. We consequently prepared the spiro -5: 5-dihydantoin described by H. Biltz, Heyn and Bergius, and succeeded in resolving the synthetic compound into its optically active components by crystallisation with brucine.

The products of partial hydrogenation of higher monoethylenic esters

The formation of “iso-oleic” acids during hydrogenation of oleic (Δ 9 : 10 - octadecenoic) acid or its esters is of importance in connection with the general theory of catalytic action at solid surfaces. The constitution of these isomeric acids has therefore been re-examined by means of the oxidising action of potassium permanganate upon hot acetone solutions of their unsaturated esters, a method which has been shown to break such compounds up almost quantitatively into derivatives of the corresponding monobasic and dibasic acids:- CH 3 . [CH 2 ] x . CH : CH. [CH 2 ] y . COOR → CH 3 . [CH 2 ] x . COOH + COOH. [CH 2 ] y . COOR. Moore has already shown that during hydrogenation a state of equilibrium is reached between the amounts of ordinary oleic acid present and the isomeric forms, and that the latter include elaidic acid together with one or more isooleic acids produced by migration of the ethylenic linkage (Δ 11 : 12 -octadecenoic acid being suggested as a possible product).