Method for producing 1,2-naphthoquinone-2-diazide-4-sulfonyl chloride

A method for producing 1,2-naphthoquinone-2-diazide4-sulfonyl chloride comprising:

• reacting 1,2-naphthoquinone-2-diazide with chlorosulfuric acid to thereby produce a mixture of a sulfonated compound and a chlorosufonated compound of the diazide;
• and
• adding at least one substance selected from among thionyl chloride and phosphorus pentachloride to the mixture for further reaction, to thereby obtain 1,2-naphthhoguinone-2-diazide-4-sulfonyl chloride, wherein conditions for the reaction between 1,2-naphthoquinone-2-diazide and chlorosulfuric acid are such that 80% or more of 1,2-naphthoquinone-2-diazide is consumed by the reaction.