Fuming sulfuric acid → HCID 10355651, compound

Participants

Reaction Steps

1-Sulfo-6-carboxy-2-aminonaphthalene, which is used as the starting compound, was hitherto unknown. However, it can be prepared according to the invention by sulfonating 2-naphthol-6-carboxylic acid in a sulfuric acid/sulfur trioxide mixture (oleum) which has a sulfur trioxide content of from 0 to 65% by weight, at a temperature of between -5° C. and +40° C., preferably at 0° to 10° C., to first give 1-sulfo-6-carboxy-2-naphthol, then isolating this compound and subsequently reacting it with ammonium hydrogen sulfite in an aqueous, alkaline medium in an autoclave at a temperature of between 100° and 200° C., preferably between 140° and 160° C.

Provenance & Evidence