Preparation method of 2-carboxybenzaldehyde

A technology of o-carboxybenzaldehyde and toluene, applied in the preparation of carboxylate/lactone, organic chemistry, etc., can solve the problems of high production cost, low purity, and low yield, and achieve low cost, high purity, and high yield. high rate effect

Active Publication Date: 2010-06-16
TAICANG YUNTONG BIOCHEM ENG
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  • Abstract
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Problems solved by technology

The yield of this method is low, and the purity is not high

Method used

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  • Preparation method of 2-carboxybenzaldehyde

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Embodiment 1

[0013] Embodiment 1: the preparation method of a kind of o-carboxybenzaldehyde of the present invention is that phthalide takes chlorobenzene as solvent, first reacts with bromine to prepare 3-bromophthalide, then adds water to initially synthesize o-carboxybenzaldehyde wet product, and finally Add water and refine to obtain high-quality o-carboxybenzaldehyde, specifically comprising the following steps: (1) preparing 3-bromophthalide: adding chlorobenzene 200kg and phthalide 225kg in a 500L reactor equipped with a reflux distillation condenser, heating and dissolving; Put 270kg of bromine into the high-level tank, raise the temperature to about 100-110°C, start to add bromine slowly, and control the speed just so that the escaping hydrogen bromide gas does not have red color, and the hydrogen bromide gas is absorbed by the absorption device as Hydrogen bromide; after bromine is added dropwise, heat up to 110-120°C and keep reflux reaction for 2 hours, then use nitrogen gas to ...

Embodiment 2

[0014] Embodiment 2: the preparation method of a kind of o-carboxybenzaldehyde of the present invention is that phthalide takes chlorobenzene as solvent, first reacts with bromine to prepare 3-bromophthalide, then adds water to initially synthesize o-carboxybenzaldehyde wet product, and finally Add water and refine to obtain fine-quality o-carboxybenzaldehyde; the mol ratio of phthalide, bromine, chlorobenzene, and water is 1:1:0.5:1, and the specific steps are as follows: (1) prepare 3-bromophthalide: ① in the reactor Add chlorobenzene, then add phthalide, heat to 100°C, then slowly add bromine dropwise; ②After the dropwise addition of bromine is completed, raise the temperature to 105°C, and keep the reflux reaction for 1.5 hours; ③Introduce nitrogen into the reaction kettle , and properly remove hydrogen bromide to make the reaction complete; ④ Cooling, the cooling temperature is 15 ° C, crystallization is precipitated, and suction filtration and centrifugation obtain 3-brom...

Embodiment 3

[0015] Embodiment 3: the preparation method of a kind of o-carboxybenzaldehyde of the present invention is that phthalide takes toluene as solvent, first reacts with bromine to prepare 3-bromophthalide, then adds water to initially synthesize o-carboxybenzaldehyde wet product, and finally Add water and refine to obtain fine-quality o-carboxybenzaldehyde, and the molar ratio of phthalide, bromine, toluene, and water is 1:3:2:20. The specific steps are as follows: (1) Preparation of 3-bromophthalide: 1. Add Add toluene, then add phthalide, heat to 110°C, and then slowly add bromine dropwise; ②After the dropwise addition of bromine is completed, raise the temperature to 120°C, and keep the reflux reaction for 2.5 hours; ③Blow nitrogen into the reaction kettle, and properly Remove hydrogen bromide to make the reaction complete; ④ cool to 20°C, precipitate crystals, filter and centrifuge to obtain 3-bromophthalide; (2) Preliminary synthesis of o-carboxybenzaldehyde wet product: add ...

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Abstract

This invention discloses a preparation method of 2-carboxybenzaldehyde. In the method, phthalide dissolved in chlorobenzene or toluene solvent is first used to react with bromine to obtain 3-bromo phthalide, and then the 3-bromo phthalide is hydrolyzed to obtain wet 2-carboxybenzaldehyde, at last the wet 2-carboxybenzaldehyde is refined by recrystal to obtain the 2-carboxybenzaldehyde. In the method of invention, the mol ratio of phthalide to bromine to chlorobenzene or toluene and to water is 1: 1-3: 0.5-2: 1-20. The preparation method of 2-carboxybenzaldehyde has the advantages of low cost,simple steps, good controlability of each step, high yield and high purity of products, and is conducive to the expanding production and realizing industrialization.

Description

technical field [0001] The invention relates to a method for preparing o-carboxybenzaldehyde, in particular to a method for preparing o-carboxybenzaldehyde with low cost, simple process, high product yield and high purity. Background technique [0002] O-carboxybenzaldehyde is an important intermediate in the synthesis of antipyretic and analgesic drugs. In the prior art, o-carboxybenzaldehyde is mostly prepared by bromination and hydrolysis of phenol. The specific method is: heat phthalide to 140-145°C, conduct bromine reaction, and control the feed rate so that the reaction tail gas is basically free Bromine vapor is discharged; after the bromine is passed through, carbon dioxide is introduced at 120°C and the residual hydrogen bromide is removed under reduced pressure; the reactant is added with water, and hydrolyzed in a boiling water bath for 0.5h; cooled, and o-carboxybenzaldehyde is precipitated, with a yield of 60% about. The yield of this method is low, and the pu...

Claims

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Application Information

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IPC IPC(8): C07C65/30C07C51/09
Inventor 张卫东
Owner TAICANG YUNTONG BIOCHEM ENG
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