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Method for preparing trichloroacetaldehyde

A technology of chloral and acetaldehyde, which is applied in the field of preparation of pesticide and pharmaceutical intermediate chloral, can solve the problems of low chlorination synthesis yield, harsh reaction conditions, large production energy consumption, etc., and achieve production cost Low, simple post-processing, good yield effect

Inactive Publication Date: 2011-06-29
INST OF PLANT PROTECTION CHINESE ACAD OF AGRI SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The direct chlorination of acetaldehyde needs to be carried out under low temperature conditions, the reaction conditions are harsh, and the production energy consumption is large
Adopt chloral aqueous solution to be substrate, and chlorination synthetic yield is lower, needs to improve

Method used

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  • Method for preparing trichloroacetaldehyde
  • Method for preparing trichloroacetaldehyde
  • Method for preparing trichloroacetaldehyde

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] Example 1: Add the catalyst antimony trichloride (SbCl) into a 1000ml four-necked flask 3 ) 2.65g and 250ml of 40% acetaldehyde solution, cool to below 10°C, open the vent valve. At the beginning, let in chlorine gas slowly (5 bubbles / min), then gradually increase to 20-30 bubbles / min, turn on the stirring switch of the thermostatic magnetic stirrer, and let the cold acetaldehyde aqueous solution stir quickly to break the chlorine bubbles. Bring it into full contact with acetaldehyde. Stepwise control of the reaction temperature: the first stage: ice water bath, the temperature of the reaction system is controlled below 20°C, preferably around 15°C. The second stage: the reaction system is placed in the temperature range of 40-60 ℃. The third stage: Put the reaction system in the temperature range of 75-90°C.

[0030] The reaction process is detected by gas chromatography. The control of the reaction time in each stage: depending on the relative content of the intermedi...

Embodiment 2

[0032] Example 2: In a 1000ml four-necked flask was added a mixture of 5.6g of catalyst ferric chloride and 4.8g of aluminum trichloride, and then 250ml of 85% acetaldehyde solution was added, cooled to below 10°C, and the vent valve was opened. At the beginning, let in chlorine gas slowly (10 bubbles / min), then gradually increase to 30-40 bubbles / min, turn on the stirring switch of the thermostatic magnetic stirrer, let the cold acetaldehyde aqueous solution quickly stir to break the chlorine bubbles, Bring it into full contact with acetaldehyde. Reaction temperature

[0033] Stage control: the first stage: ice water bath, the temperature of the reaction system is controlled below 20°C, preferably around 15°C. The second stage: the reaction system is placed in the temperature range of 40-60 ℃. The third stage: Put the reaction system in the temperature range of 75-90°C.

[0034] The reaction process is detected by gas chromatography. The control of the reaction time in each st...

Embodiment 3

[0036] Example 3: Add a mixture of 7.5 g of catalyst mercury sulfate and 4.8 g of concentrated sulfuric acid into a 1000 ml four-necked flask, then add 250 ml of 20% acetaldehyde solution, cool to below 5° C., and open the vent valve. At the beginning, let in chlorine gas slowly (5 bubbles / min), then gradually increase to 20-40 bubbles / min, turn on the stirring switch of the thermostatic magnetic stirrer, and let the cold acetaldehyde aqueous solution stir quickly to break the chlorine bubbles. Bring it into full contact with acetaldehyde. Stepwise control of the reaction temperature: the first stage: ice water bath, the temperature of the reaction system is controlled below 10°C, preferably around 5°C. The second stage: Put the reaction system in a temperature range of 45-50°C. The third stage: Put the reaction system in the temperature range of 75-90°C.

[0037] The reaction process is detected by gas chromatography. The control of the reaction time in each stage: depending ...

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Abstract

The invention discloses a method for preparing trichloroacetaldehyde through catalysis of aqueous solution of aldehyde. The aqueous solution of aldehyde is taken as a raw material, and the method comprises the following steps of: performing chlorination on aldehyde by controlling reaction temperature in the presence of a single or mixed catalyst; and after the reaction is finished, performing azeotropy dehydration through a latent solvent, and distilling a product to obtain high-purity trichloroacetaldehyde. The method has the advantages of high yield and light environmental pollution, and can be applied to preparation of a small amount of trichloroacetaldehyde in a laboratory and industrial production.

Description

Technical field [0001] The method relates to a method for preparing fine chemical products, specifically, a method for preparing pesticides and pharmaceutical intermediates chloroacetaldehyde. Chloral is an important organic synthesis intermediate and an important halogen derivative. It is widely used in the production of pesticides, medicines, organic raw materials and other fields. Background technique [0002] Chloral, English name Chloral, CAS NO: 75-87-6, molecular weight: 147.38, molecular formula C 2 HCl 3 O, a colorless and volatile oily liquid with a pungent odor. Melting point: -57.5, boiling point: 97.7, relative density (water = 1): 1.51, relative density (air = 1): 5.1, saturated vapor pressure (kPa): 4.67 / 20℃, solubility: soluble in water, ethanol , Ether, chloroform, etc. Trichloroacetaldehyde is an important chemical intermediate, widely used in the preparation of various compounds such as medicines (such as chloramphenicol), pesticides (such as trichlorfon, DDT...

Claims

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Application Information

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IPC IPC(8): C07C47/16C07C45/63
Inventor 折冬梅黄啟良李凤敏陈大舟
Owner INST OF PLANT PROTECTION CHINESE ACAD OF AGRI SCI
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