Year: 1887

page_text: Date of Application, 20th Apr., 1887.
Specification Accepted, 20th May, 1887.
1, ANDREAS ALEXANDER VALE of 34 Mildmay Chambers, Bishopsgate Street in the
City of London, Merchant, do hereby declare the nature of this invention and in
what manner the same is to be performed to be particularly described and ascer-
tained in and by the following statement :-
Crude anthracene, as obtained in crystalline form directly from the boiling products
of tar oils, contains still a number of foreign carbon compounds which act more or
less detrimentally when manufacturing alizarine and other colouring inatters therefrom.
A portion thereof can no doubt be removed by recrystallisation from benzole, benzino
alcohol and other similar solvents, to which has lately been added oleic acid, described
in German Patent No. 38417. That is to say the crude anthracene can be enriched
on account of the greater solubility of some of the impurities thereof in the said
solvents than of the anthracene itself. But this enrichment is only attained at the cost
of very considerable losses, and it has the greater disadvantage that one of the most
detrimental impurities of anthracene namely carbazole, remains, because its solution
in the said solvents is quite as difficult as, and according to Becchi, more so than,
that of anthracene.
In order to remove the carbazole therefore, a special process must be used, the best
known being the distillation of crude anthracene over caustic potash, which combines
with the carbazole, but which process causes great loss.
From these causes crude anthracene is almost exclusively supplied in commerce,
the percentage of pure anthracene in which does not exceed about 40 per cent., or
the so called "washed " anthracene obtained from these, having not more than about
50 per cent. of puro anthracene.
The present invention is based upon the hitherto unknown fact that all impurities
of anthracene, including carbazole are much more easily solublo in the pyridine,

page_text: chinoline and aniline bases than anthracene itself, so that it is possible by the use of
these substances to obtain by a single solution process not only anthracene in a very
concentrated state but also quite free or nearly so, from carbazole and its homologues.
Particularly suitable for this purpose are the tar bases (pyridine bases) as contained
in the light oils of coal tar and which may be most conveniently obtained therefrom
by the process described in Patent No. 9614 of 1885 and in German Patents
No. 34947, 36372. By dissolving one part of unwashed crudo anthracene of about
30 per cent. in 1 parts of such tar bases, anthracene of considerably over 80 per
cent. is at once obtained, which is almost entirely free from carbazole. Aniline and
chinoline may be used as solvents with a like result, though not quite as favorable.
The power of these basic bodies to enrich anthracene is so great that they may even
be mixed to a considerable extent with benzole or similar bodies without losing their
properties to any considerable extent. Thus in using a mixture of equal parts of
benzole and tar bases (pyridine bases) in the proportions of 1 part anthracene and
2 parts of this solvent, anthracene of about 80 per cent. purity was still obtained,
while a mixture of equal parts of benzole and aniline only yielded anthracene of about
75 per cent. and in the latter case there were greater losses.
Having now particularly described and ascertained the nature of this said invention
and in what manner the same is to be performed I declare that what I claim is:-
The process of purifying crude anthracene by treating the same with pyridine,
aniline and chinoline bases or with mixtures of these with benzole, hydrocarbons
and similar solvents whereby the impurities are dissolved leaving the anthracene
undissolved.