反应详情

The water-moist 2-mercaptophenylurea obtained according to European Pat. No. 0,039,483, Example 1, paragraph 1, by reacting 150 parts of 2-aminobenzothiazole with 150 parts of sodium hydroxide and working up the mixture with water, or an appropriate amount of the sodium or potassium salt of the said 2-mercaptophenylurea, is dissolved in 500 parts of 50% strength acetic acid, and 118 parts of diketene are then added dropwise in the course of 2 hours at 45° to 50° C. Stirring is continued for 1 hour, after which the mixture is heated to the reflux temperature and kept at a temperature of 95° C.-100° C. for 2 hours. It is then cooled to room temperature, and the precipitated 2-acetonylbenzothiazole of the formula ##STR13## is isolated by filtration and dried in vacuo at 60° C.-80° C. 151.7 parts of a product of melting point 118° C.-119° C. are obtained; this corresponds to a yield of 79.4%, based on 2-aminobenzothiazole employed.

1. additionare then added dropwise in the course of 2 hours at 45° to 50° C
2. temperatureafter which the mixture is heated to the reflux temperature
3. waitkept at a temperature of 95° C.-100° C. for 2 hours