反应详情

A solution of 20 parts by volume of concentrated hydrochloric acid in 100 parts by volume of water is added dropwise to a boiling mixture of 168 parts of 2-amino-3-cyano-4-ethoxythiophene and 500 parts by volume of methanol. The mixture is refluxed for a further 2 hours and diluted with 400 parts by volume of water, and the product is filtered off under suction, washed with water and dried to give 136 parts of 2-amino-3-cyano-4-hydroxythiophene. The sample recrystallized from acetic acid does not melt below 300° C. and has the following analytical values:

1. temperatureThe mixture is refluxed for a further 2 hours
2. filtrationthe product is filtered off under suction
3. washwashed with water
4. customdried