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Method for preparing dibromomethane

A technology of dibromomethane and dichloromethane, which is applied in the field of dibromomethane preparation, can solve the problems of complex process, difficult operation, low conversion rate, etc., and achieve the effects of reducing diffusion, improving operating environment and increasing yield

Active Publication Date: 2009-04-22
TIANJIN CHANGLU HAIJING GRP CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

At present, the arsenic trioxide method, i.e. the tribromomethane method, is mostly used to prepare methylene bromide. The process mainly includes the preparation and heating of sodium arsenite solution, synthesis reaction, water washing fractionation, drying and dehydration, and heating rectification. There are many types, difficult operation, low conversion rate, high hazard of raw materials, and high pollution. Due to the consumption of 1.2t / t of diarsenic trioxide and 8.3t / t of tribromomethane per ton, the production cost is high, and highly toxic substances are used in the production process. - arsenic, thus seriously limiting the industrial production of this method

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  • Method for preparing dibromomethane

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Embodiment 1

[0021] First, add 250kg of dichloromethane and 10kg of aluminum trichloride to the 500L synthetic kettle, and then use 4m 3 The flow rate of / h is fed into the hydrogen bromide gas containing 99% pure, and at the same time, it is heated with 0.1MPa steam. During this period, the dichloromethane volatilized is recovered to the synthesis tank after forced condensation to continue to participate in the reaction.

[0022] After 22 hours of reaction, when the temperature of the feed liquid in the synthesis tank reached 65° C., the content of dichloromethane in the synthesis liquid was 0.15%, that of chlorobromomethane was 8.9%, and that of dibromomethane was 85%. After the obtained synthetic liquid is washed and separated by soda ash, the pH of the oil phase is 6, and then it is passed into the rectification tower for rectification. At this time, the temperature at the top of the tower is 65°C, and the temperature of the material is 97.5°C. It can produce 680kg of dibromomethane, th...

Embodiment 2

[0024] First, add 500kg of dichloromethane and 14kg of aluminum trichloride to the 500L synthetic kettle, and then use 6m 3 The flow rate of / h is passed into the hydrogen bromide gas containing pure 99.2%, while heating with 0.3MPa steam, during which the volatilized dichloromethane returns to the reactor to participate in the reaction after being forced to condense.

[0025] After 28 hours of reaction, when the reaction temperature reaches 72°C, the content of dichloromethane in the synthetic liquid is 0.377%, that of chlorobromomethane is 12.327%, and that of dibromomethane is 87.262%. Phase PH is 6.2, and weight is 980kg, passes into the rectification tower again rectification, this moment, tower top temperature is 67 ℃, and material taking temperature is 97 ℃, makes methylene bromide 850kg after rectification, product quality 99.7%, color degree is 10 # , the acidity (as hydrogen bromide) is 0.0025%, and the density is 2.49g / cm 3 .

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Abstract

The invention provides a method for preparing dibromomethane. The method is divided into three parts of synthesis, alkali cleaning and rectification; in the method, hydrogen bromide gas with purity of not less than 99 percent and methylene dichloride are used as raw materials and generate a dibromomethane synthetic solution under the condition of catalytic heating; and the synthetic solution is subjected to alkali cleaning and rectification to prepare the dibromomethane. The method has the advantages that the prepared dibromomethane is characterized in that the purity of the dibromomethane reaches over 99.5 percent; the acidity (counted by hydrogen bromide) is not more than 0.01 percent; the chroma is not more than 20<#>; and the density is between 2.48 and 2.50 g / cm. The process improves the yield of products, greatly improves operating environment and reduces the diffusion of harmful substances in air.

Description

technical field [0001] The invention relates to a method for preparing dibromomethane, in particular to a method for synthesizing dibromomethane with gas containing not less than pure hydrogen bromide and dichloromethane, followed by alkali washing and rectification to prepare dibromomethane. Background technique [0002] Dibromomethane (alias: methylene bromide) is a colorless transparent liquid, specific gravity: 2.4969 (20°C). At present, the arsenic trioxide method, i.e. the tribromomethane method, is mostly used to prepare methylene bromide. The process mainly includes the preparation and heating of sodium arsenite solution, synthesis reaction, water washing fractionation, drying and dehydration, and heating rectification. There are many types, difficult operation, low conversion rate, high hazard of raw materials, and high pollution. Due to the consumption of 1.2t / t of diarsenic trioxide and 8.3t / t of tribromomethane per ton, the production cost is high, and highly tox...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C19/075C07C17/20B01J27/125B01J27/128
Inventor 张德强李萌魏炳举田凤麟杨金水陈向锋
Owner TIANJIN CHANGLU HAIJING GRP CO LTD
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