4-NITRO-5-METHYL~2-SULPHOBENZOIC ACID 
185 
ing from carbon tetrachloride, it gave a melting point of 90° 
which corresponds to the acid chloride of this acid. 
While the use of the chlorsulphonic acid is of moderate value 
for the preparation as given above, it has been found that in the 
case of the isomeric 4-nitro-5-methyl-2-sulphobenzoic acid in 
which we are interested, the yield approaches zero. The change 
which is produced in this case runs almost wholly along the 
line of the production of a soluble crystalline substance which 
is formed as a by-product in the making of the acid chlorides 
by all the methods tried. This body was not investigated. A 
few analyses showed that it probably was neither the acid nor 
the acid potassium salt. 
DERIVATIVES OBTAINED BY THE ACTION OF AMMONIA ON THE 
ACID CHLORIDES. 
A. From the Symmetrical Acid Chloride . — The symmetrical 
acid chloride is only slightly acted upon in nonaqueous solutions 
by ammonia, but when treated with strong aqueous ammonia, 
the pure chloride may be dissolved at boiling temperature with 
the formation of a substance soluble in water which might be 
either the diamide (I), or the ammonium salt of the imide (II). 
or 
CONH^ 
\/ 
SO.NHs 
II CH 
NO 
0=0 
SO2 
>N • NH4 
The product is the latter, since it can be formed from the 
imide by simple neutralization with ammonia, also because when 
its solution is treated with sodium hydroxide as in the Kjel- 
dahl method and the mixture distilled, the presence of one 
and only one ammonium group is shown. The passage from 
the o-diamide to the ammonium salt, moreover, would be very 
easy under the conditions of the experiment. No other sub- 
stance was recovered in the preparation, excepting, of course, 
the ammonium chloride formed in the reaction. 
