Phosphorus oxychloride → 4-Chlorosulfonyl-2-(2-Pyridylazo)-1-Naphthol

Participants

Reaction Steps

A mixture consisting of 10 g of 4-hydroxy-3-(2-pyridylazo)-1-naphthalenesulfonic acid prepared by the process of Japanese patent application (OPI) No. 35533/78 (the term "OPI" as used herein means "unexamined published patent application"), 100 ml of sulforan, and 15 ml of phosphorous oxychloride was heated at an inner temperature of from 55° to 65° C. for 3 hours while stirring. The reaction mixture was cooled to room temperature and poured into 1 l of ice-water. The precipitated crystals were collected by filtration, washed with water, and air-dried to obtain 10.1 g of the desired compound.

Provenance & Evidence