Mr Mills, The Ketodilactone of Benzophenone, etc. 149 
The Ketodilactone of Benzophenone-2-4-2'-4'-tetracarboxylic 
Acid. (Preliminary Note.) By W. H. Mitts, M.A., Jesus 
College. 
[Read 10 May 1915.] 
With the object of obtaining a dicyclic compound of the type 
Aa Le 
Cie 
which should be capable of resolution into optically active com- 
ponents, the oxidation of di-m-xylyl ketone has been investigated. 
By heating this ketone with dilute (9 per cent.) nitric acid for 
about 70 hours it was completely converted into a mixture of acids 
in which dimethylbenzophenone dicarboxylic acids predominated. 
On further oxidation with alkaline potassium permanganate the 
mixed acids gave an excellent yield of benzophenone-2-4-2’-4/- 
tetracarboxylic acid (I), an easily soluble compound which is 
transformed with the greatest readiness into its sparingly soluble 
ketodilactone (II). The transformation is best effected by acidi- 
fying the aqueous solution strongly with hydrochloric acid and 
heating on the water bath. The ketodilactone is then deposited in 
the course of a few minutes as a heavy crystalline powder (found 
C=598; H=2°5; C,,H,O; requires C= 60:0; H = 2°4 per cent.). 
This compound melts at 410° and is very sparingly soluble in the 
common solvents. 
CO,H CO,H CO,H 
| 
SS 
CC JE =O8 —CO,H 
| | | 
bo o——-C___0 0-——CH 
| | | 
—CO,H = CO— COm: 
| | 
CO.H CO,H COME 
I te iat 
