Method for preparing CLT acid (6-chloro-3-aminotoluene-4-sulfoacid) by utilizing o-chlorotoluene direct nitrification method

Abstract

The invention relates to a method for preparing 6-chloro-3-aminotoluene-4-sulfoacid (hereinafter referred to as CLT acid) in a direct nitrification way by taking o-chlorotoluene as a raw material. The method comprises the following steps of: obtaining o-chlorotoluene nitrate by taking acidic Beta zeolite as a catalyst and acetyl nitrate as a nitrifying agent; reducing the o-chlorotoluene nitrate by utilizing iron powder; recrystallizing the reduced product and separating out 6-chloro-3-aminotoluene crystal and 6-chloro-4-aminotoluene containing little 6-chloro-3-aminotoluene by adopting an acid extraction method; adding dichlorobenzene and sulfuric acid in the 6-chloro-3-aminotoluene crystal, and carrying out sulfonation at 170-190 DEG C to obtain the CHLOROT acid; and carrying out sulfonation on the 6-chloro-4-aminotoluene containing little 6-chloro-3-aminotoluene to obtain 2B acid containing little CLT acid. The invention has the characteristics of low pollution, high yield, simple process, low device requirements, and the like.

Description

[technical field] [0001] The present invention relates to the manufacture method of 6-chloro-3-aminotoluene-4-sulfonic acid (hereinafter referred to as CLT acid), specifically refer to directly nitrate o-chlorotoluene with acetyl nitrate in the presence of β-zeolite, continue to reduce, Sulfonation, a method of making CLT acid. The invention is characterized in that the equipment is simple, the yield is high, no highly toxic bromine and chlorine are used, the amount of "three wastes" is small, and the CLT acid is produced under environment-friendly conditions. [Background technique] [0002] There are many synthesis routes of CLT acid: toluene sulfonation route, m-toluidine route, o-chlorotoluene bromination route, o-chlorotoluene direct nitration route, m-xylene route, etc. The o-chlorotoluene bromination route has the advantages of short process route and high yield, such as CN 1099027, in the presence of iodine catalyst, o-chlorotoluene is brominated with bromine at 0-5°...

AI Technical Summary

Problems solved by technology

The disadvantage of this method is that it needs to use bromine and chlorine that are strictly controlled by the state for transportation and use, and requires an autoclave and a bromine recovery device, which requires high equipment requirements.

The direct nitration route of o-chlorotoluene, for example, Zhao 58-96056, nitrates o-chlorotoluene with mixed acid to obtain 6-chloro-3-nitrotoluene, and then undergoes platinum-catalyzed hydrogenation reduction to generate 6-chloro-3-aminotoluene, Then bake and sulfonate with concentrated sulfuric acid to obtain CLT acid. This method has simple process, low equipment requirements, and less "three wastes", but the yield of 6-chloro-3-nitrotoluene is only 43%.