Process for the selective preparation of N-substituted 1,4-diamino-2-nitrobenzenes

US5091581A · kind A · utility

Assignee

• Hans Schwarzkopf GmbH · DE

Inventor

• Winfried Seidel · Obertshausen, DE

Key dates

• Filing date: May 7, 1990
• Grant date: Feb 25, 1992
• Expiry date: May 7, 2010

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C09B51/00
• WIPO field: Pharmaceuticals
• WIPO sector: Chemistry

Abstract

The invention relates to a process for the selective preparation of N.sup.4 -substituted 1,4-diamino-2-nitrobenzenes of the general formula I ##STR1## in which R.sub.1 denotes hydrogen, halogen, (C.sub.1 -C.sub.4) alkyl or (C.sub.1 -C.sub.4) alkoxy, it being possible for the carbon atoms to be arranged in straight-chain or branched form, and R.sub.2 represents a radical --COO--CH(A)--CH(B)--D with the meanings A=H, B=H, D=Cl, A=H, B=CH.sub.3, D=Cl, A=H, B=H, D=CH.sub.2 Cl or A=CH.sub.3, B=H and D=Cl (compounds of the general formula Ia) or a radical--CH(X)--CH(Y)--Z with the meanings X=H, Y=H, Z=OH, X=CH.sub.3, Y=H, Z=OH, X=H, Y=H, Z=CH.sub.2 OH or X=H, Y=CH.sub.3 and Z=OH (compounds of the general formula Ib) ##STR2## which is characterized in that 1,4-diamino-2-nitrobenzenes of the general formula II ##STR3## wherein R.sub.1 has the abovementioned meaning, are reacted in a first stage with an approximately equimolar amount of a chloroalkyl chloroformate of the general formula Cl--COO--CH(A)--CH(B)--D, wherein A, B and D have the above-mentioned meanings, in a predominantly aqueous medium which contains--based on the water present--not more than 20 percent by weight of an organic …