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.
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.
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 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 .
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 184.108.40.206- tetrahydro- acenaphthylene glycol. The resolution of this compound was
attempted, in a similar manner to trans-acenaphthylene
glycol, but without success.
As four racemic 220.127.116.11-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
It was found that, using platinum oxide as a catalyst two 18.104.22.168-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 22.214.171.124-tetrahydro acenaphthylene glycol prepared
from cis-acenaphthylene glycol was quite a different
Using palladium deposited on barium sulphate as
catalyst, however, both cis - and trans-acenaphthylene
glycol, on hydrogenation, were converted into the hydr
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.