Process for continuously preparing nitro-xylene isomer monomer

Abstract

The present invention is continuous xylene isomer monomer nitrifying and rectifying process with sulfuric acid and nitric acid mixture to obtain nitro xylene isomer monomer. The optimized process has product yield over 97 %; consumption of xylene, nitric acid and sulfuric acid of 750kg / ton, 465kg / ton and 40kg / ton separately; and purity of the 2, 6-dimethyl nitrobenzene, 2, 4-dimethyl nitrobenzene, 3, 4-dimethyl nitrobenzene, 2, 3-dimethyl nitrobenzene and 2, 5-dimethyl nitrobenzene up to 99.5 %. When the process has the material changed from xylene to o-xylene or p-xylene and the technological conditions changed correspondingly, 3, 4-dimethyl nitrobenzene, 2, 3-dimethyl nitrobenzene and 2, 5-dimethyl nitrobenzene may be produced.

Description

technical field [0001] The invention relates to a method for preparing nitroxylene isomer monomers by continuous nitration and continuous rectification with nitric acid, sulfur mixed acid and xylene isomer monomers, in particular to using nitric acid, sulfur mixed acid and m-xylene, ortho-xylene respectively. Nitration reaction of toluene and p-xylene and rectification to prepare 2-nitro-m-xylene, 4-nitro-m-xylene, 4-nitro-o-xylene, 3-nitro-o-xylene and 2-nitro-p-xylene Methods. technical background [0002] There are six isomers of nitroxylene, all of which have the molecular formula C 8 h 9 NO 2 , there are five kinds of industrial application value: 2-nitro-m-xylene is also known as 2,6-dimethylnitrobenzene or 2-nitro-1,3-dimethylbenzene; 4-nitro-m-xylene Xylene is also known as 2,4-dimethylnitrobenzene or 4-nitro-1,3-dimethylbenzene; 4-nitro-o-xylene is also known as 3,4-dimethylnitrobenzene Or 1,2-dimethyl-4-nitrobenzene; 3-nitro-o-xylene is also known as 2,3-dimet...

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Problems solved by technology

Another major disadvantage is the need for post-treatment of spent acid

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