Patent GB-190114-A (GB)
Title: Improvements in and relating to the process for the manufacture of acid h (amino-naphthol-disulphonic 1.8.3.6.)
IPC: C07C309/40
Filed: 1922-09-19
Abstract: 1 : 8-Aminonaphthol-3 : 6-disulphonic acid H is obtained by the following series of reactions.  Naphthalene is sulphonated with oleum, the product nitrated, and after first eliminating the nitrous vapours by means of a current of air the resulting nitronaphthalene trisulphonic acid is precipitated as sodium salt by pouring into water and salting out; the nitro body is then neutralized with soda and reduced in aqueous solution by means of hydrogen under pressure in presence of a catalyst.  The catalysts mentioned are reduced metals (nickel, cobalt, copper, iron) or their oxides and they may be used upon inert supports such as charcoal, pumice or quartz.  Any halogen, sulphur, selenium or tellurium in organic combination should not be present during the reduction process.  The aminonaphthalene trisulphonic acid solution is then saponified by heating with caustic soda at 150-180 DEG  C. and the H-acid precipitated by mineral acid. The Specification as open to inspection under Sect. 91 (3) (a) describes also the use of nitrates, silicates and fluosilicates of the catalytic metals as catalysts and of metal oxides, kieselguhr, silicates and fluosilicates as additional carriers for the catalyst. In place of hydrogen, water gas, "poor gas" or sulphur dioxide may be used for the catalytic reduction.  The process is also stated to be applicable to the production of other aminosulphonic acids such as Cleve's acids, Freund's acid, S-acid and metanilic acid.  This subject-matter does not appear in the Specification as accepted.ALSO:1 : 8-Aminonaphthol-3 : 6-disulphonic acid H is obtained by the following series of reactions.  Naphthalene is sulphonated with oleum, the product nitrated, and after first eliminating the nitrous vapours by means of a current of air the resulting nitronaphthalene trisulphonic acid is precipitated as sodium salt by pouring into water and salting out; the nitro body is then neutralized with soda and reduced in aqueous solution by means of hydrogen under pressure in presence of a catalyst.  The catalysts mentioned are reduced metals (nickel, cobalt, copper, iron) or their oxides, and they may be used upon inert supports such as charcoal, pumice or quartz.  Any halogen, sulphur, selenium, or tellurium, in organic combination, should not be present during the reduction process.  The aminonaphthalene trisulphonic acid solution is then saponified by heating with caustic soda at 150-180 DEG  C. and the H-acid precipitated by mineral acid.  The Specification as open to inspection under Sect. 91 (3) (a) describes also the use of nitrates, silicates and fluosilicates of the catalytic metals as catalysts and of metal oxides, Kieselguhr, silicates and fluosilicates as additional carriers for the catalyst.  In place of hydrogen may be used water-gas, "poor gas" or sulphur dioxide for the catalytic reduction.  The process is also stated to be applicable to the production of other aminosulphonic acids such as Cleve's acids, Freund's acid, S-acid, and metanilic acid.  This subject-matter does not appear in the Specification as accepted.