Nitric Acid → N-(5-Chloro-2-hydroxy-3-nitrophenyl)acetamide

224.5 g of sulphuric acid (50% w/w) was dissolved in 300 ml of water and cooled to 25° C. while stirring under a mild nitrogen purge. 185.1 g (1 mole) of N-(5-chloro-2-hydroxyphenyl)acetamide prepared according to Example 1a was added to the diluted sulphuric acid and mixed intensively. 4 ml of nitric acid 65% w/w was added to the foam formed on top of the reaction mixture at low stirring speed. The stirring speed was increased and 75 ml of nitric acid 65% w/w was added in 45 minutes, while maintaining the temperature between 23 and 26° C. The mixture was stirred vigorously for an additional 1 hour at 23-26° C. Then the mixture was cooled to 0-5° C. and vigorously stirred at this temperature for 1 hour. The solid was filtered off quickly, washed three times with 300 ml of cold water, sucked for at least 30 minutes and dried at 50° C. and 100 mbar under a gentle nitrogen stream till dry.