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Method for preparing acetyl bromide from phosphorus tribromide

A technology of phosphorus tribromide and acetyl bromide, applied in chemical instruments and methods, preparation of organic compounds, preparation of carboxylate, etc., can solve the problem of wasting a lot of manpower and material resources, increasing production costs of enterprises, unsuitable control of the amount of liquid bromine, etc. question

Inactive Publication Date: 2015-04-22
JIANGSU DACHENG PHARMA TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this method is the same as the traditional method for preparing acetyl bromide. In the reaction process, liquid bromine and acetic anhydride are used for synthetic reaction, but the amount of liquid bromine in the reaction process should not be controlled. In the reaction process, excessive bromine often occurs due to the excessive amount of bromine. Bromination produces excessive bromide-bromoacetyl bromide, the purity of the product is low, and at the same time, hydrogen bromide gas will be produced due to the reaction. Although the gas can be absorbed by water, a large amount of manpower and material resources are wasted for collection and treatment, which greatly Increased the production cost of the enterprise

Method used

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  • Method for preparing acetyl bromide from phosphorus tribromide
  • Method for preparing acetyl bromide from phosphorus tribromide
  • Method for preparing acetyl bromide from phosphorus tribromide

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] Example 1: like figure 1 Shown:

[0029] 1) Add 180g (3mol) acetic acid and 306g (3mol) acetic anhydride to a dry and clean 1000ml four-neck flask, stir, cool down to below 20°C, add 830g (3.06mol) phosphorus tribromide dropwise, and slowly heat up to 30°C ℃ for 2 hours, then heated to reflux for 0.5 hours.

[0030] 2) Start steaming at normal pressure for 6 hours, then distill under reduced pressure for 2 hours until no liquid is evaporated.

[0031] 3) A total of 1087g of acetyl bromide was distilled, and the GC purity was 98.3%;

[0032] Keep the water bath at 80°C, add 100ml of 80°C hot water dropwise to the flask, cool to obtain white crystals, filter and dry to obtain 185g of phosphorous acid with a content of 98.6%.

Embodiment 2

[0033] Example 2: Example 2 repeats the test of example 1: as figure 1 Shown:

[0034] 1) Add 180g of acetic acid and 306g of acetic anhydride to a dry and clean 1000ml four-neck flask, stir, cool down to below 20°C, add 830g of phosphorus tribromide dropwise, slowly raise the temperature to 30°C and keep it warm for 2 hours, then raise the temperature to reflux, keep warm and reflux 0.5 hours.

[0035] 2) Start steaming at normal pressure for 8 hours, then distill under reduced pressure for 2 hours until no liquid is evaporated. Acetyl bromide 1092g was obtained with a purity of 98.6%.

[0036] 3) Add 55ml of water and the mother liquor of Example 1 to the distillation residue to obtain 243g of phosphorous acid with a content of 98.1%.

Embodiment 3

[0037] Example 3: Embodiment 3 repeats the test of example 2 again: as figure 1 Shown:

[0038] 1) Add 180g of acetic acid and 306g of acetic anhydride to a dry and clean 1000ml four-neck flask, stir, cool down to below 20°C, add 830g of phosphorus tribromide dropwise, slowly raise the temperature to 30°C and keep it for 2 hours, then heat it up to reflux and keep it at reflux for 0.5 Hour.

[0039] 2) Start steaming at normal pressure for 7 hours, then distill under reduced pressure for 2 hours until no liquid is evaporated. Acetyl bromide 1090g was obtained with a purity of 98.2%.

[0040] 3) Add 55ml of water and the mother liquor of Example 1 to the distillation residue to obtain 246g of phosphorous acid with a content of 98.3%.

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Abstract

The invention discloses a method for preparing acetyl bromide from phosphorus tribromide. The method comprises the steps of carrying out reaction on raw materials at the temperature of 20-40 DEG C, and after reaction, distilling to obtain the target product acetyl bromide, wherein the raw materials are acetic acid, acetic anhydride and phosphorus tribromide. The reaction equation is as follows: 6(acetic acid)+6(acetic anhydride)+6(phosphorus tribromide)->18(acetyl bromide)+hexametaphosphate. Bromine is not added into the raw materials, thus excessive bromination can be avoided and bromoacetyl bromide which is an excessive bromination product can not be generated. Due to the combination of acetic acid and acetic anhydride, water generated during the polymerization of phosphorous acid which is a reaction intermediate product can be consumed effectively. The raw materials which participate in reaction can be reacted almost completely, thus the conversion rate of the product can be improved.

Description

technical field [0001] The invention relates to the field of synthesis of organic compounds, in particular to a method for preparing acetyl bromide from phosphorus tribromide. Background technique [0002] Acetyl bromide is an intermediate of dyes, medicines, and pesticides, and can also be used in other organic synthesis, with an annual consumption of about 2,000 tons. There are two old preparation methods: [0003] 1) React with acetic anhydride and bromine, brominate at 80°C, and then add bromine between 95°C and 125°C. It takes about 2.5h. After adding, continue to reflux for 3h and leave overnight. Refined by fractional distillation; the mol yield of acetyl bromide produced by this method is low, about 45%. The reaction equation is: [0004] [0005] 2) React with acetic acid and phosphorus tribromide, mix the acetic acid and phosphorus tribromide, raise the temperature to 40°C and keep it warm for 5 hours, and then separate into layers. The upper layer is the b...

Claims

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Application Information

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IPC IPC(8): C07C53/40C07C51/60
CPCC07C51/60C07C53/40
Inventor 杨书华任有俊吴永张兆春史永林朱云董长生
Owner JIANGSU DACHENG PHARMA TECH CO LTD
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