Method for preparing CLT acid (2-amino-4-methyl-5-chlorobenzene sulfonic acid) by continuous catalytic hydrogenation reduction

A catalytic hydrogenation and catalyst technology, applied in the preparation of sulfonic acid, organic chemistry, etc., can solve the problems of low selectivity, high equipment investment, difficult to control, etc. Effect

Active Publication Date: 2015-02-18
ZHEJIANG QINYAN TECH CO LTD
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Problems solved by technology

At present, there are many research reports on the preparation of CLT acid by catalytic hydrogenation reduction. There are mainly the following methods: 1. Using Pd / C as a catalyst, a batch reaction method is used in a high-pressure hydrogenation reactor to carry out catalytic hydrogenation reduction preparation CLT acid, the method has the following problems: (1) the volume of the reactor is relatively large, resulting in higher equipment investment
(2) The reaction stability is poor, the product dechlorination is high, the selectivity is low, resulting in more by-products
(3) There is a large loss of catalyst active components and a short catalyst life, resulting in high catalyst costs; 2. Using Pt / C as a catalyst, a batch reaction method is used in a high-pressure hydrogenation reactor for catalytic hydrogenation reduction to prepare CLT acid , the method has the following problems: (1) The volume of the reactor is relatively large, resulting in high equipment investment
(2) Although the catalytic hydrogenation reduction effect is very good when Pt / C is used as the catalyst, the dechlorination of the product is low, but because the market price of CLT acid is only 25,000-28,000 yuan / ton, and the price of Pt / C is relatively high, In the batch reaction mode, the loss of catalyst active components is large, resulting in high catalyst costs
3. Utilize granular carbon-supported or Al2O3-supported Pt-type catalysts, in a fixed-bed reactor, adopt the mode of continuous feeding, continuous discharging and continuous feeding of hydrogen to carry out continuous catalytic hydrogenation reduction to prepare CLT acid, This method has the following problems: (1) The reaction temperature and pressure are high, and the requirements for the material and pressure resistance level of the equipment are also high, resulting in high investment in equipment
(2) The fixed bed reactor has high requirements on the purity of the raw materials, otherwise, due to too many impurities in the material, it will easily cause the poisoning and failure of the granular catalyst, which will cause a large risk in large-scale production and is difficult to control. In addition, due to the purity of the CLT acid nitro material Not very high, so not suitable for continuous catalytic hydrogenation reduction to prepare CLT acid

Method used

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  • Method for preparing CLT acid (2-amino-4-methyl-5-chlorobenzene sulfonic acid) by continuous catalytic hydrogenation reduction
  • Method for preparing CLT acid (2-amino-4-methyl-5-chlorobenzene sulfonic acid) by continuous catalytic hydrogenation reduction
  • Method for preparing CLT acid (2-amino-4-methyl-5-chlorobenzene sulfonic acid) by continuous catalytic hydrogenation reduction

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Experimental program
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Effect test

Embodiment 1

[0021] Add 300g of 10% mass percent, PH=7.2 aqueous solution of 2-amino-4-methyl-5-chlorobenzenesulfonic acid into the 2-stage series tank type continuous reactor, and add 6g into the first-stage reactor. For a Pt / C catalyst with a Pt content of 3%, add 4g of a Pt / C catalyst with a Pt content of 3% in the second-stage autoclave, replace the air with nitrogen twice, and replace the nitrogen twice with hydrogen, then start stirring , raise the temperature of the reaction material to 60°C, continuously feed hydrogen, control the hydrogen pressure at 1MPa, and then start to continuously pump 2-nitro-4 with a weight percentage of 10% and a pH of 7.5 at a feed rate of 1000ml / h -Aqueous solution of methyl-5-chlorobenzenesulfonic acid, while controlling the reaction temperature at 70°C, adopting the methods of continuous feeding of hydrogen, continuous feeding and continuous discharging, to carry out catalytic hydrogenation reduction to prepare CLT acid, and the CLT acid aqueous soluti...

Embodiment 2

[0026] Add 300g of 18% by weight of 2-amino-4-methyl-5-chlorobenzenesulfonic acid (CLT acid) aqueous solution (PH=7.5) into the 2-stage series tank type continuous reactor, in the first stage Add 10.8g3%Pt / C catalyst in the autoclave, add 3.6g3%Pt / C catalyst in the second-stage autoclave, replace the air twice with nitrogen, and replace the nitrogen twice with hydrogen, start stirring, and The temperature of the reaction material was raised to 70°C, hydrogen gas was continuously fed in, and the pressure of the hydrogen gas was controlled at 1MPa. Then, at a feed rate of 1000ML per hour, continuous pumping of 18% by weight of 2-nitro-4-methyl-5- The aqueous solution of chlorobenzenesulfonic acid (CLT acid nitro) (PH=7.5), while controlling the reaction temperature at 70°C, adopts the methods of continuous feeding of hydrogen, continuous feeding and continuous discharging, to prepare CLT acid by catalytic hydrogenation reduction, The CLT acid aqueous solution after the reaction ...

Embodiment 3

[0031]300g of 10% by weight of 2-amino-4-methyl-5-chlorobenzenesulfonic acid (CLT acid) aqueous solution (PH=7.5) was respectively added to the 3-stage series tank type continuous reactor, and in the first Add 45g90% Raney nickel catalyst to the first-stage autoclave, add 15g90% Raney nickel catalyst to the second-stage autoclave, replace the air twice with nitrogen, and replace the nitrogen twice with hydrogen, start stirring, and put the reaction Raise the temperature of the material to 65°C, continuously feed hydrogen, control the hydrogen pressure at 2MPa, and then start to continuously pump 10% by weight of 2-nitro-4-methyl-5-chloro at a feed rate of 1000ML per hour Aqueous solution of benzenesulfonic acid (CLT acid nitro) (PH=7.5), while controlling the reaction temperature at 80°C, adopting the method of continuous feeding of hydrogen, continuous feeding and continuous discharging, to prepare CLT acid by catalytic hydrogenation reduction, reaction The completed CLT acid...

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Abstract

The invention provides a method for preparing CLT acid (2-amino-4-methyl-5-chlorobenzene sulfonic acid) by continuous catalytic hydrogenation reduction. The 2-amino-4-methyl-5-chlorobenzene sulfonic acid (CLT acid) can be prepared from a water solution of 2-nitro-4-methyl-5-chlorobenzenesulfonic acid by adopting a continuous catalytic hydrogenation reduction method. According to the method provided by the invention, the loss of a catalyst caused by frequent filtration during the intermittent reaction process can be effectively reduced, and the internal circulating utilization of the catalyst can be realized to prolong the service life of the catalyst; and simultaneously, when the CLT acid is prepared by continuous catalytic hydrogenation reduction according to the method, the volume of a reaction kettle is smaller, the reaction stability is good, the dechlorination of a product is lower, the selectivity is high, and byproducts are fewer.

Description

technical field [0001] The invention relates to the field of organic chemical synthesis, in particular to a method for preparing CLT acid through continuous catalytic hydrogenation reduction. Background technique [0002] CLT acid, also known as 2-amino-4-methyl-5-chlorobenzenesulfonic acid, is an important red organic pigment intermediate, mainly used in the manufacture of organic pigments Jinguanghong C, rubber scarlet LG and Lithol scarlet, etc. , which are widely used in the formulation of inks, paints and coatings, and in the coloring of plastics and rubber. At present, the synthesis method of CLT acid used at home and abroad is basically the toluene sulfonation method, that is, the finished product of CLT acid is obtained after toluene sulfonation, chlorination, nitration, reduction, acid analysis, pressure filtration and drying. [0003] For the reduction process of CLT acid, the iron powder reduction process is widely used at home and abroad at present. A large amou...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C309/48C07C303/22
Inventor 仇文仲邹刚王晓辉徐钦政陈昭文柳锐赵伟
Owner ZHEJIANG QINYAN TECH CO LTD
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