Patent · US Expired

Process for the preparation of isolated 3,4-diaminobenzenesulphonic acid

US6787666B2 · kind B2 · utility

0Cited by

8References

5Claims

0Family size

Assignee

Bayer Chemicals AG · DE

Inventors

Gunter Rauchschwalbe · Leverkusen, DE
Herbert Emde · Cologne, DE
Wolfram Kissener · Neunkirchen, DE

Key dates

Filing date	Sep 16, 2003
Grant date	Sep 7, 2004
Priority date	—
Expiry date	Sep 16, 2023

Classification

Technology area (CPC C)Chemistry; Metallurgy
CPC primaryC07C303/06
WIPO fieldOrganic fine chemistry
WIPO sectorChemistry

Abstract

Described herein is a process for the preparation of 3,4-diaminobenzenesulphonic acid, characterized in that 1,2-diaminobenzene is reacted with anhydrous sulphuric acid which optionally comprises SO3 in up to stoichiometric amount, at a temperature in the range from 100 to 160° C. with stirring for a reaction time of from 1 to 20 hours; water or ice is added to the reaction mixture, optionally with cooling, up to a sulphuric acid concentration in the range from 30 to 75% by weight, based on the total mixture; the 3,4-diaminobenzenesulphonic acid precipitated out of the reaction mixture is filtered off, optionally washed with dilute sulphuric acid and worked up.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.