1971 年 29 巻 12 号 p. 1129-1134
Until the completion of this investigation 1, 7-Cleve acid has been produced in an industrial scale by sulfonation of naphthalene, followed by nitration and reduction. However, its separation from accompanying 1, 6-Cleve acid, Peri-acid and others is not so easy, and it has been difficult to obtain the acid in pure form enough for industrial use.
The authors have succeeded in synthesizing the acid by sulfonation of 1-naphthol followed by hydrolysis and Bucherer reaction.
(1) Hydrolysis of di-sulfonated naphthol to mono-sulfonic acid directly by use of the remaining sulfuric acid.
(2) Addition of ammonia and ammonium bisulfite to the sodium 1-naphthol-7-sulfonate solution (obtained by sodation of calcium 1-naphthol-7-sulfonate solution separated by liming the mixture of the monosulfonic and sulfuric acid solution) and heating the mixture.
The process is now established and has been already carried out since a few years ago.