To 211 g. (1 mole) of 3-nitrophthalic acid (p. 408) in a 300-cc. round-bottomed flask fitted with a reflux condenser is added 205 g. (190 cc., 2 moles) of acetic anhydride (99–100 per cent). The mixture is heated to gentle boiling until the acid is completely dissolved and then for about ten minutes longer. The hot mixture is poured (Hood) into a 15-cm. porcelain dish and allowed to cool. The crystal mass is ground thoroughly in a mortar and filtered by suction. The crystals are returned to the mortar and the filtrate (about 140 cc.) is placed in a 300-cc. distilling flask. The crystals are ground with 150 cc. of alcohol-free ether (Note 1) and filtered. They are again returned to the mortar and similarly washed.

After drying in the air for a short time, the product is dried to constant weight at 105°. The yield of product melting at 163–164° is 170–180 g. (88–93 per cent of the theoretical amount). The acetic acid filtrate is distilled with a thermometer in the liquid until the temperature is 150°. The distillate amounts to about 120 cc. The residue is poured into the mortar and, after cooling, is ground with some of the ether used in washing the original crystals. Thus about 10 g. of a product melting at 160–163° is obtained.