反应详情

温度

100 °C

2 parts of monoethyl maleate are added with stirring to 25 parts of water containing 2 parts of p-hydrazinobenzene sulphonate and 1 part of sodium carbonate. The mixture is heated at 100° C for 5 hours. The resulting solution is warmed with sodium carbonate and the pH finally adjusted to 3-4 with hydrochloric acid. The 3carboxy-1-(4'-sulphophenyl)-5-pyrazolidone thus formed is filtered off and dried between 50°-100° C. The actual weight yield is 4 parts of strength 74% (determined by N.M.R.) which represents a yield of 76%.