GB457518A - Process for the manufacture of 2.4-dinitro-3:6-dihalogenanilines - Google Patents

Abstract

2 : 4-Dinitro-3 : 6-dihalogenanilines are prepared (1) by treating 3 : 6-dihalogen-4-nitranilines with nitric acid of specific gravity about 1,54, or (2) by treating 3 : 6-dihalogen-N-alkylsulphonylanilines with nitric acid of specific gravity not below about 1,4 in the absence of sulphuric acid, and subsequently removing the alkylsulphonyl group by hydrolysis, or (3) by treating 3 : 6-dihalogen-N-arylsulphonyl group by hydrolysis, Process (1) may be effected in the presence or absence of sulphuric acid; if sulphuric acid is present the 2 : 4-dinitro-3 : 6-dihalogenaniline is obtained directly, but if sulphuric acid is absent the 3 : 6-dihalogen-4-nitrophenylnitramine is first obtained, and is then converted into the 2 : 4-dinitro-3 : 6-dihalogenaniline by treatment with sulphuric acid. The products are useful as diazo components in the manufacture of azo dyes. In the examples, (1) 3 : 6-dichloro 4-nitraniline is treated with sulphuric acid monohydrate and nitric acid of specific gravity 1,54; 2 : 4-dinitro-3 : 6-dichloraniline is obtained; (2) 2 : 4 - dinitro - 3 : 6 - dibromaniline is obtained similarly from 3 : 6-dibromo-4-nitraniline; (3) 3 : 6-dichloro-4-nitraniline is treated with nitric acid of specific gravity 1,54, and the 3 : 6-dichloro-4-nitrophenylnitramine so obtained is treated with sulphuric acid, this yielding 2 : 4-dinitro-3 : 6-dichloraniline; (4) N-methanesulphonyl-3 : 6-dichloraniline is boiled with nitric acid of specific gravity 1,4 to yield N-methanesulphonyl - 2 : 4 - dinitro - 3 : 6-dichloraniline, which is then warmed with sulphuric acid to split off the methanesulphonyl group; (5) N-p-toluenesulphonyl-3 : 6-dichloraniline is treated with nitric acid of specific gravity 1,54 to yield N-(3<1>-nitro-4<1>-methylbenzenesulphonyl)-3 : 6-dichlor-2 : 4-dinitraniline, which is then warmed with sulphuric acid to split off the arylsulphonyl group; 3 - nitro - 4 - methylbenzenesulphonic acid is obtained as a by-product. The Specification as open to inspection under Sect. 91 states that the 2 : 4-dinitro-3 : 6-dihalogenanilines may be prepared by nitrating N-alkylsulphonyl- or N-arylsulphonyl-4-nitro-3 : 6-dihalogenanilines, and includes an example in which N-p-toluenesulphonyl-4-nitro-3 : 6-dichloraniline is treated with nitric acid of specific gravity 1,52 to yield an initial product identical with that of example 5 above, which is then hydrolyzed as described in that example. This subject-matter does not appear in the Specification as accepted.