Amino naphthalene sulphonic acids prepn. from corresp. nitro cpds. - using mostly used Raney nickel under specified conditions

• Main Authors: STEFFAN,GUIDO,.DR, KAISER,REINHARD,.DR, BARTH,OTTO, BEHRE,HORST,.DR, ZANDER,JUERGEN,.DR, BECKER,HANS-JOACHIM,.DR
• Format: Patent
• Language: English; German
• Published: 26.04.1979
• Edition: 2
• Subjects: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION ORPROCESSING OF GOODS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINSTCLIMATE CHANGE

A process for prepg. aminonaphthalene sulphonic acids by catalytic hydrogenation of the salts of nitronaphtalene sulphonic acids comprises the following. A mixture of used Raney nickel catalyst and fresh Raney nickel catalyst is suspended in water and/or an aq. soln. of the hydrogenation product. The suspension under 100-300 bars hydrogen pressure is heated to 100-180 degrees C. At this temp. a soln. or suspension of the nitronaphthalene sulphonic acid at pH 6-9 is added in amt. such that the content of the nitro cpd. in the reaction mixture is not above 5% of the total weight and the final concn. of aminonaphthalene sulphonic acid is 5-40% of the total reaction mixture. The products are intermediates in the prepn. of dyes. The process gives a 10% yield increase compared with previous processes (95-99% and a space/time yield of 1-3 kg. amino cpd./l. capacity/hr.); also the bulk of the catalyst may be recycled and a faster reaction rate is obtained.