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A kind of preparation method of 4,5-dihydroxy-2-methylbenzoic acid

A technology of methylbenzoic acid and dihydroxytoluene, which is applied in the fields of fine chemicals and pharmaceutical intermediates, can solve the problems of heavy pollution, complicated steps, and difficulty in obtaining raw materials, and achieve the effects of simple and safe operation, easy access to raw materials, and easy products

Active Publication Date: 2016-10-26
YANCHENG TEACHERS UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The source of raw materials used in this method is not easy, thus limiting its use
(2) Utilizing 3,4-dimethoxybenzoic acid as a raw material, reacting with methyl iodide in the presence of isobutyllithium to generate 35% of 4,5-dimethoxy-2-methylbenzoic acid, At the same time, it is accompanied by a large number of by-products, which have no production value
However, in order to generate 3,4-dihydroxy-2-methylbenzoic acid, a large amount of boron tribromide is required, which is costly and polluting, and is not suitable for large-scale production
[0005] It can be seen that the existing synthetic methods are either difficult to obtain raw materials, many by-products, low yield, high cost, or complicated steps, unsafe, and serious pollution

Method used

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  • A kind of preparation method of 4,5-dihydroxy-2-methylbenzoic acid
  • A kind of preparation method of 4,5-dihydroxy-2-methylbenzoic acid
  • A kind of preparation method of 4,5-dihydroxy-2-methylbenzoic acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0051] Embodiment 1 prepares intermediate III

[0052] Take the preparation of 2-bromo-4,5-dihydroxytoluene as an example

[0053] Into a 500 ml three-necked round bottom flask equipped with a mechanical stirrer, 24.8 g of 4-methylbenzene-1,2-diol (0.2 mol) and 200 ml of dichloromethane were added and stirred to form a solution. Place the reaction flask in a cooling tank of acetone and dry ice and keep stirring. 38.4g of bromine (0.24mol) was added dropwise within half an hour, and the temperature in the reaction flask was kept at -70°C to -30°C during the dropwise addition. After the dropwise addition, the cooling tank was removed and the temperature was naturally raised to room temperature. The solvent was evaporated to dryness, recrystallized, filtered, and sucked dry to obtain 38.2 g of product with a yield of 94.2% and a purity of 93.8%. The crude product was recrystallized from ethyl acetate / petroleum ether (1:4) to obtain 35.8 g of a solid with a purity of 98.1%.

[...

Embodiment 2

[0055] Embodiment 2 prepares intermediate V

[0056] Take the preparation of 3,4-dibenzyloxytoluene as an example

[0057] To a 500 ml three-neck round bottom flask equipped with a mechanical stirrer, first add 66.7 g of potassium carbonate (0.48 mol), 24.8 g of 4-methylbenzene-1,2-diol (0.2 mol) and 250 ml of acetone, and stir for half Hour. 60.8 g of benzyl chloride (0.48 mol) was added to the mixture, heated to reflux for 5 hours, and the reaction was tracked by TLC. After the reaction, filter, add water to stir, filter under reduced pressure, collect the solid, and drain to obtain 56.9 g of a light yellow solid with a yield of 93.4% and a purity of 95.4%.

[0058] If the same mole of benzyl bromide is used instead of benzyl chloride, 57.4 g of solids are obtained with a purity of 96.1%.

Embodiment 3

[0059] Embodiment 3 prepares intermediate IV

[0060] Taking intermediate V as raw material to prepare 4,5-dibenzyloxy-2-bromotoluene as an example

[0061] Into a 500 ml three-neck round bottom flask equipped with a mechanical stirrer, add 30.4 g of intermediate V (0.1 mol) and 200 ml of dichloromethane, and stir to form a solution. Place the reaction flask in a cooling tank of acetone and dry ice and keep stirring. Within half an hour, 19.2 g of bromine (0.12 mol) was added dropwise to the solution. During the dropwise addition, the temperature in the reaction flask was kept at -70°C to -30°C. After the dropwise addition, the cooling tank was removed and the temperature was naturally raised to room temperature. The solid was collected by filtration under reduced pressure and sucked dry to obtain 36.5 g of a light yellow solid with a purity of 96.4% and a yield of 95.3%.

[0062] If NaBr-Br with bromine equimolar 2 Using the same operation method instead of bromine, 37.1 g...

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Abstract

The invention discloses a preparation method of 4,5-dihydroxyl-2-methyl benzoic acid and belongs to the fields of fine chemical engineering and medicine intermediates. The preparation method of 4,5-dihydroxyl-2-methyl benzoic acid comprises the following steps: preparing an intermediate III or V by taking 4-methylbenze-1,2-diphenol as a raw material, then preparing an intermediate IV by virtue of the intermediate III or V, then transforming the intermediate IV into an intermediate II, and finally preparing 4,5-dihydroxyl-2-methyl benzoic acid by virtue of the intermediate II. The preparation method of 4,5-dihydroxyl-2-methyl benzoic acid has the advantage that the problems that raw materials are difficult to acquire, byproducts are many, yield is low, cost is high, steps are miscellaneous, safety can not be guaranteed and serious pollution is produced in the prior art are overcome.

Description

technical field [0001] The invention relates to a preparation method of 4,5-dihydroxy-2-methylbenzoic acid, which belongs to the fields of fine chemical industry and pharmaceutical intermediates. Background technique [0002] 4,5-dihydroxy-2-methylbenzoic acid is an important pharmaceutical and fine chemical intermediate. Its structural formula is as follows: [0003] [0004] For the preparation method of 4,5-dimethoxyl-2-methylbenzoic acid, there are following several kinds: (1) utilize 4,5-dimethoxyl-2-methylbenzaldehyde as raw material, by oxidation Generate 4,5-dimethoxy-2-methylbenzoic acid; after deprotection, the target product is obtained. The source of raw materials used in this method is not easy, thereby limiting its use. (2) Utilizing 3,4-dimethoxybenzoic acid as a raw material, reacting with methyl iodide in the presence of isobutyllithium to generate 35% of 4,5-dimethoxy-2-methylbenzoic acid, At the same time, it is accompanied by a large number of by-p...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C65/03C07C51/377
CPCC07C37/62C07C41/16C07C41/22C07C51/15C07C51/377C07C39/27C07C43/205C07C43/225C07C65/21C07C65/03
Inventor 孙雅泉
Owner YANCHENG TEACHERS UNIV
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