Claims
- 1. A Process for the preparation of an 2-aminobenzene-1,4-disulphonic acid of the formula (I) ##STR5## in which X represents hydrogen or chlorine,
- in which a 4-chloro-3-nitrobenzene-sulphonic acid of the formula (II) ##STR6## in which X represents hydrogen or chlorine,
- is reacted with sodium sulphite in an aqueous alkaline medium and then reduced with iron, in which process the reaction with sodium sulphite is carried out at 40.degree. to 90.degree. C., no intermediate isolation is carried out before the reduction with iron and the 2-aminobenzene-1,4-disulphonic acid of the formula (I) is isolated after filtering off the iron oxide, after a pH of <1 has been established in the filtrate at 70.degree. to 90.degree. C. using mineral acid and after the filtrate has been cooled.
- 2. The process of claim 1, in which 1.0 to 1.5 moles of sodium sulphite are employed per mole of the compound of the formula (II).
- 3. The process of claim 1, in which the reaction with sodium sulphite is carried out at 60.degree. to 80.degree. C.
- 4. The process of claim 1, in which the reaction with sodium suphite is carried out at a pH of 8 to 12.
- 5. The process of claim 1, in which the reduction with iron is carried out at 85.degree. to 100.degree. C. and at a pH in the range from 5 to 7.
- 6. The process of claim 1, in which sulphuric acid is used as the mineral acid.
- 7. The process of claim 1, in which the filtrate is finally cooled to a temperature of 10.degree. to 30.degree. C.
Priority Claims (1)
Number |
Date |
Country |
Kind |
3937342 |
Nov 1989 |
DEX |
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Parent Case Info
This application is a continuation, of application Ser. No. 815,901, filed Dec. 31, 1991, now abandoned, which is a continuation of application Ser. No. 583,188, filed Oct. 5, 1990, now abandoned.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
2965675 |
Novello et al. |
Dec 1960 |
|
4179476 |
Franz et al. |
Dec 1979 |
|
Foreign Referenced Citations (2)
Number |
Date |
Country |
77192 |
Apr 1905 |
DE2 |
285488 |
May 1929 |
GBX |
Continuations (2)
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Number |
Date |
Country |
Parent |
815901 |
Dec 1991 |
|
Parent |
583188 |
Oct 1990 |
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