PURPOSE: To extremely economically purify N-(2-hydroxyethyl)-2methyl-3- carboxcylic acid amido-quinoxaline-1,4-di-N-oxide in high recovery ratio under given conditions, by using water as a recrystallization solvent.
CONSTITUTION: An enamine expressed by formula I (R1 and R1' are OH, alkoxy or alkyl) is reacted with benzofuroxan enpressed by formula II (R2 is H, alkyl o akoxy) in the presence of ammonia or a primary amine, etc., to give crude N-(2-hydroxyethl)-2-methyl-3-carboxylic acid amido-quinoxaline-1,4-di-N-oxide expressed by formula III, which is then made into an aqueous solution at 40W100°C, particularly hot aqueous solution in 2W9g/100ml concentration at 60W95°C and then slowly cooled to 0W30°C, particularly about 0W15°C, recrystallized and purified.
FUJITA KATSUHIKO
KAWAMURA SHINICHI
