39 
synthesis of Alizarine from Anthracene and succeeded in this 
about a year and a half ago. ‘ 
Anthracene C,,H,,, is a carburetted Hydrogen, obtained 
from coal tar and belonging to the same type as Benzole; in 
fact it may be considered as being formed by the condensation 
of three molecules of Benzole into one, as illustrated in the 
following graphic formula : 
CH—CH=CH CH—CH=C—CH=C—CH=CH 
| | | | | | 
CH—CH=CH CH—CH=C—CH=C—CH=CH 
Benzole C,H, - Anthracene C,,H,, 
In 1888 Woskressensky obtained a _ substance, called 
Quinone by distilling Quinic Acid with Sulphuric Acid and 
black Oxide of Manganese. Its formula is C,H,O,. A similar 
substance, Anthraquinone was obtained by Laurent, derived 
from Anthracene. They are constituted as follows : 
CH—CH=CO CH—CH=C—CH=C—CH=CO 
II ee | | | = 
CH--CH=CO CH--CH=C—CH=C—CH=CO 
Quinone C,H,0O, Anthraquinone C,,H,O, 
Greebe and Liebermann conceived the opinion that Alizarine, 
whose properties as a weak Acid have long been recognized, 
might be the Quinone Acid of Anthracene and could be ob- 
tained by substituting two Hydrogen atoms in Anthraquinone 
by the Hydroxyl group, OH. Strictly speaking Alizarine, ac- 
cording to this formula and the manner of its formation, is not 
an Acid, as it does not contain the group COOH, but it must 
be considered as a diatomic Phenol. In the constitutional 
formula given above I have assigned the two Hydroxyls to 
contiguous Carbon atoms because this explains on the simplest 
manner the compounds which Alizarine forms with diatonic 
metals, Ba, Ca, &. By treatment with Bromine they first 
obtained the Bibromide of Anthraquinone : 
C,,H,O, + 4Br= C,;,H,Br, 0, + 2HBr. 
