That the higher melting form of acenaphthylene glycol is of cis- and the lower melting form of trans-configuration, has been further established by the optic cal resolution of the lower melting glycol. This was effected by converting it into the di-l- menthoxy acetates, followed by fractionation. Hydrolysis of the resulting highly laevorotatory ester yielded an optically active trans-acenaphthylene glycol. The specific rotation of this compound was found to vary with the solvent used, being positive in solvents of low dipole moment, and negative in solvents of high dipole moment, while for solvents of intermediate polarities (e.g. ethyl and methyl alcohol), the specific rotation was found to be zero, or too small to be determined.

The preparation of acenaphthylene from acenaphthene has been carried out under varying conditions, and a maximum yield of about 50% has been obtained. From acenaphthylene the acenaphthylene glycols have begin prepared by way of the dibromides. 'In this case various modifications have been introduced into the method described in the literature. The direct oxidation of acenaphthylene to the glycols was attempted but found to be unsuccessful.

It was found that, using platinum oxide as a catalyst two 1.2.3.4-tetrahydro acenaphthylene glycols could be isolated. One of these, prepared from trans-acenaphthylene glycol, was identical with the compound obtained by chemical reduction of acenaphthene quinone, which must therefore be of trans-configuration. The other 1.2.3.4-tetrahydro acenaphthylene glycol prepared from cis-acenaphthylene glycol was quite a different compound.

An attempt to prepare acenaphthylene glycol by a method recently described by Blount and Weissberger, by reduction of acenaphthene quinone with sodium amalgam, led to the isolation of a 1.2.3.4- tetrahydro- acenaphthylene glycol. The resolution of this compound was attempted, in a similar manner to trans-acenaphthylene glycol, but without success.

As four racemic 1.2.3.4-tetrahydro acenaphthylene glycols are possible, the hydrogenations of the cis - and trans-acenaphthylene glycols were carried out in order to determine, if possible, whether the compound obtained by the chemical reduction was of cis- or trans configuration.

It thus appears that the catalysts have a specifi effect, hydrogenation, using palladium as a catalyst, tending to take place more readily at the hydroxyl grou whereas, when platinum is used the reduction occurs mor readily within the naphthalene nucleus.

The higher melting acenaphthylene glycol, on conversion to the di-l-menthoxy acetate, 'fractionation and hydrolysis of the pure ester obtained, was recovered unchanged, in agreement with its established cis- configuration .

Several methods'of purification of the lower melting (trans -) modification of the glycol have been used, the most satisfactory being the removal of the higher melting (cis-) glycol in the form of its acetone cornpound.

Using palladium deposited on barium sulphate as catalyst, however, both cis - and trans-acenaphthylene glycol, on hydrogenation, were converted into the hydr carbon acenaphthene.