Synthesis method for 2, 6-dihydroxytoluene

A technology of dihydroxytoluene and a synthesis method, which is applied in the field of chemical material preparation, can solve the problems of impurities in post-processing, difficult to control reaction conditions, multiple by-products, etc., and achieves the advantages of mild reaction conditions, saving drying time, and optimizing product color and luster. Effect

Active Publication Date: 2015-02-11
JIANGSU DINGYE PHARMA CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The acetic anhydride vapor used in this route is poisonous, and this synthesis route is relatively complicated, which will produce more by-products, which is not convenient for the separation and purification of the product, making the post-processing relatively complicated and polluting the environment. Severe, uncontrollable reaction conditions

Method used

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  • Synthesis method for 2, 6-dihydroxytoluene
  • Synthesis method for 2, 6-dihydroxytoluene
  • Synthesis method for 2, 6-dihydroxytoluene

Examples

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Embodiment 1

[0044] Step 1): In a 2000L diazonium reactor, add 1750kg of 40% by mass sulfuric acid aqueous solution and heat it with steam. When the temperature rises to 90-95°C, start to drop 225kg of 3-chloro-2-methylaniline at a uniform rate. The dripping is completed within 1.5-2h, and the reaction is kept for 1.0h. Pass salt water to cool to below 5℃. Control the temperature at 0-5°C, drop 380kg of sodium nitrite aqueous solution with a mass percentage of 30% within 3-4h, keep it for 1.0h after the addition, and obtain a suction-filtered diazonium liquid for later use.

[0045] Step 2): Inject 780kg of water or recovered mother liquor water into the hydrolysis kettle, add 10kg of active rare earth catalyst lanthanum phosphate, turn on the stirring, add 560kg of concentrated sulfuric acid, 700kg of toluene or the secondary extracted toluene extract at a constant speed, and heat to reflux. Add the diazonium solution obtained in step 1) dropwise within 3-4h, keep it for 0.5h and then cool ...

Embodiment 2

[0049] Step 1): In a 2000L diazonium reactor, add 1969kg of a 40% mass percent sulfuric acid aqueous solution and heat it with steam. When the temperature rises to 90-95°C, start dropping 225kg of 3-chloro-2-methylaniline at a uniform rate. The dripping is completed within 1.5-2h, and the reaction is kept for 1.0h. Pass salt water to cool to below 5℃. Control the temperature at 0-5°C, add 390 kg of sodium nitrite aqueous solution with a mass percentage of 30% in 3-4 hours, keep the temperature for 1.0 hour after the addition, and obtain the diazonium liquid by suction filtration for use.

[0050] Step 2): Inject 780kg of recovered mother liquor water into the hydrolysis kettle, add 15kg of active rare earth catalyst lanthanum phosphate, turn on the stirring, add 600kg of concentrated sulfuric acid and 700kg of secondary extraction toluene extract at a constant speed, and heat to reflux for 3-4h The diazonium liquid obtained in step 1) is added dropwise, after holding for 0.5h, t...

Embodiment 3

[0054] Step 1): In a 2000L diazonium reactor, add 1850kg of 40% sulfuric acid aqueous solution and heat with steam. When the temperature rises to 90-95°C, start to add 225kg of 3-chloro-2-methylaniline dropwise at a uniform rate. The dripping is completed within 1.5-2h, and the reaction is kept for 1.0h. Pass salt water to cool to below 5℃. Control the temperature at 0-5°C, drop 385 kg of a 30% mass percent sodium nitrite aqueous solution within 3-4 hours, keep it for 1.0 h after the addition, and obtain a suction-filtered diazonium solution for later use.

[0055] Step 2): Inject 780kg of recovered mother liquor water into the hydrolysis kettle, add 13kg of active rare earth catalyst lanthanum phosphate, turn on the stirring, add 560kg of concentrated sulfuric acid and 700kg of toluene extract for secondary extraction at a constant speed, and heat to reflux for 3-4h The diazonium liquid obtained in step 1) is added dropwise, the temperature is lowered after holding for 0.5h, th...

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Abstract

The invention discloses a synthesis method for 2, 6-dihydroxytoluene. According to the method, the 2, 6-dihydroxytoluene is obtained from 3-chloro-2-methylaniline is used as raw materials through diazotization reaction, lanthanum phosphate catalysis hydrolysis, alkali dissolution and acidification. The synthesis method has the advantages that (1) the raw material resources are wide; (2) the process is simple, and the operation is easy; (3) active rear earth is used as catalysts, and the color and luster of products can be optimized; (4) the reaction conditions are relatively mild, and the safety factor is high; (5) the total yield is as high as more than 65 percent, the purity reaches more than 99.0 percent, in addition, solvents can be recovered and reused, and the energy-saving and emission-reduction effects are obvious.

Description

One technical field [0001] The invention relates to a method for synthesizing 2,6-dihydroxytoluene and belongs to the technical field of chemical material preparation. This method is suitable for the synthesis of 2,6-dihydroxytoluene with 3-chloro-2-methylaniline as raw material. 2. Background technology [0002] 2,6-Dihydroxytoluene is an important fine chemical intermediate, widely used in pigments, dyes, hair dyes, synthetic resins, medicines, pesticides, photography and other fields. [0003] At present, 2,6-dihydroxytoluene mainly has the following synthetic methods: [0004] (1) High-pressure hydrogenation hydrolysis method using 2,6-dinitrotoluene as raw material. [0005] [0006] This method is divided into two steps. First, 2,6-dinitrotoluene is used for hydrogenation reaction under high temperature and high pressure, and then under acetic acid system, palladium carbon is used as a catalyst, and then hydrolyzed to obtain 2,6-dihydroxytoluene . However, the method needs to...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C39/08C07C37/055
Inventor 戴铭周永广
Owner JIANGSU DINGYE PHARMA CO LTD
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