PURPOSE: Hypoxanthine and phosphorus oxychloride are heated in the presence of a tertiary amine at a specific temperature to produce 6-chloropurine used as an intermediate of purine derivatives in high yield.

CONSTITUTION: On the reaction between hypoxanthine and phosphorus oxychloride in the presence of a tertiary amine such as N,N-dimethylaniline or α- picoline, the mixture of raw materials is rapidly heated over 130°C in 10W15min or the temperature is kept at lower than 90°C for 4hr to give the objective compound. Since phosphorus oxychloride acts as a solvent as well as a reagent, the amount is 10W20 times the molar quantity of hypoxanthine. The tertiary amine is 2W3 times the molar amount of hypoxanthine.