SINGLE POT PROCESS FOR THE PRODUCTION OF 2-ACETAMIDONAPHTHALENE-6-SULPHONIC ACID WITH A HIGH PURITY

摘要

1. A single-vessel process for preparing 2-acetaminonaphthalene-6-sulfonic acid of high purity by sulfonating 2-hydroxynaphthalene with concentrated sulfuric acid, converting the 2-hydroxynaphthalenesulfonic acid formed with ammonia in the presence of ammonium hydrogensulfite into 2-aminonaphthalene-6-sulfonic acid (Bucherer reaction) and N-acetylating the latter to give 2-acetaminonaphthalene-6-sulfonic acid, which comprises, after diluting the sulfonating melt with water, substantially removing any impurities still present in the resulting aqueous solution of 2-hydroxynaphthalene-6-sulfonic acid, in particular 2-hydroxynaphthalene, by extraction with toluene or xylene and/or clarification using active carbon.