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Method for preparing dichloro acetaldehyde from hydrated chloral

A technology of hydrated chloral and anhydrous chloral, which is applied to the preparation of carbon-based compounds, the preparation of organic compounds, chemical instruments and methods, etc. It can solve the problems of difficult industrial production, high production costs, and affecting reactions, etc. problems, achieve the effects of reducing concentrated sulfuric acid pollution, reducing equipment investment, and increasing operability

Inactive Publication Date: 2004-10-27
SHANGHAI INST OF TECH
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Problems solved by technology

[0004] But there is following shortcoming in said method: (1) this method will be raw material with the anhydrous chloral of new distillation, but chloral is easy to absorb water, can form hydrated chloral crystal in reaction process, affects The smooth progress of the reaction makes it more difficult to avoid the precipitation of solid hydrates during industrial production; (2) the reaction is more violent, and a large amount of ice and salt are needed to control it at about 0°C, which not only has high production costs, but is also unsafe
In short, this route has harsh conditions and is difficult to use in industrial production

Method used

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  • Method for preparing dichloro acetaldehyde from hydrated chloral

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Embodiment

[0015] Add 166 grams of chloral hydrate and 165 milliliters of benzene (volume ratio is about 1:1) into a 1000 milliliter three-necked flask, and connect an electric stirrer, a thermometer and a water separator respectively. Adjust the temperature to about 110°C and heat for about 1 hour and 30 minutes. When the amount of water in the water separator no longer increases, remove the water separator and use an ice-water bath instead, add 160 ml of trimethyl phosphite dropwise from the constant pressure dropping funnel, and control the dropping rate so that the reaction temperature does not exceed 30°C. The dropwise addition time is about 1 hour and 10 minutes. The reaction was continued for 15 minutes. After the reaction is completed, the solvent benzene and other impurities below 100°C are distilled off. Cool slightly, add 30 ml of distilled water and a small amount of concentrated sulfuric acid, distill under normal pressure, collect fractions at 89.0-91.0°C, and obtain 104....

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Abstract

A process for preparing dichloro acetaldehyde from trichloro acetaldehyde includes mixing hydrated trichloro acetaldehyd with benezene, azeotropy to remove water, dripping trimethyl phosphite, removing low-boiling-point (lower than 100 deg.C) substance, hydrolyzing and dewatering by concentrated sulfuric acid.

Description

technical field [0001] The invention relates to a method for preparing dichloroacetaldehyde from hydrated trichloroacetaldehyde, which belongs to the technical field of fine chemical synthesis. Background technique [0002] In 1955, Allen et al. found that the aqueous solution of the well-known pesticide dichlorvos would be hydrolyzed into dimethyl phosphate and dichlorovinyl alcohol in an alkaline medium. The latter was very unstable and rearranged into dichloroacetaldehyde. But this principle has not been applied in practice. It was not until 1976 that Swretoseawsk et al proposed a related method for preparing dichloroacetaldehyde: they used anhydrous chloraldehyde as a raw material to react with trimethyl phosphite, and the prepared dichlorvos could be obtained with an equivalent amount of water. Hydrolyzed into the hydrate of dichloroacetaldehyde, without separation, the hydrate can be dehydrated into dichloroacetaldehyde by distilling with concentrated sulfuric acid: ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C45/61C07C45/66C07C47/14
Inventor 孙小玲王世慧朱贤张静东薛善峰郑育卿
Owner SHANGHAI INST OF TECH
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