22346-43-6

4-Hydroxy-7-methylaminonaphthalene-2- sulfonic acid [22346-43-6], N-methyl J acid, is produced by reaction of 2,5-dihydroxynaphthalene-7-sulfonic acid with methylamine and aqueous sodium bisulfite at 96 C for 36 h (yield 83 %). It is used to produce C.I. Reactive Orange 4, C.I. Reactive Orange 13, and C.I. Reactive Red 33.