4-NITRO-5-METHYL-2-SULPHOBENZOIC ACID 
203 
Methyl Ester Sulphone Chloride. 
NOg . CHg . CgHs . COOCHg . S3,^C1 
This substance was prepared from the unsymmetrical acid 
chloride by dissolving in hot alcohol. The warming was kept 
up only long enough to obtain solution. When the solution was 
cooled, the sulphone chloride ester separated in long platelike 
crystals. It was washed with a very little absolute alcohol under 
suction and dried. It is very soluble in benzene, alcohol, acetone, 
ether and chloroform, and on this account a great deal of diffi^ 
culty was encountered in purifying it. The solvent finally used 
was ligroin, in which the ester is not very soluble. Drying was 
by suction in a partial vacuum. After standing over night in 
a desiccator, the product, which has a melting point of 101°, 
was analyzed. 
Chlorine was estimated by saponification with dilute potas- 
sium hydroxide in a small Erlenmeyer flask, then by exactly 
neutralizing with nitric acid, and finally by titrating with .1 N 
silver nitrate solution, using potassium chromate as the indi- 
cator. Sulphur was determined by the Liebig and nitrogen bj 
the Gunning methods. 
.2278 g. substance gave .1828 g. barium sulphate. 
.1140 g. substance gave .0892 g. barium sulphate. 
.2553 g. substance required 7.77 cc .1084N HCl. 
.1985 g. substance required 6.09 cc .1084N HCl. 
.1859 g. substance required 6.37 cc .IN Silver nitrate. 
.2959 g. substance required 10.02 cc .IN Silver nitrate. 
Theory for CgHsOeNSCl Pound 
Sulphur, 10.92 per cent. 10.75 - 11.02 per cent. 
Nitrogen, 4.77 per cent. 4.66 - 4.61 per cent. 
Chlorine, 12.08 per cent. - 12.09 - 12.01 per cent. 
Methyl Benzoic Ester of the Sulphonic Acid. 
NOg . CH3 . CeHg . cdoCHs . SoJoH 
The methyl ester acid was prepared as described, by boiling 
either acid chloride with methyl alcohol for some time and 
evaporating to a syrup. On cooling it slowly formed crystals 
which on account of their extreme solubility were not purified. 
The identification was by means of the barium salt, which could 
be made easily. The silver salt, which was very soluble, was 
made but not analyzed. It was used in the preparation of the 
dimethyl ester. 
