Manufacture of substantially pure monochloroacetic acid

A technology of chloroacetic acid and dichloroacetic acid, applied in the preparation of carboxylate, the preparation of organic compounds, chemical instruments and methods, etc., can solve problems such as uneconomical, and achieve the effect of improving selectivity

Active Publication Date: 2009-09-09
BUSS CHEMTECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although the process is disclosed for use with mixtures containing up to about 50% by weight of dichloroacetic acid, such amounts of said impurities require two passes through the hydrogenation step before melt crystallization, which is not economical.

Method used

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  • Manufacture of substantially pure monochloroacetic acid
  • Manufacture of substantially pure monochloroacetic acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] Hydrogenation of a mixture containing 35.0% by weight dichloroacetic acid

[0033] A tubular reactor with a Venturi mixer and equipped with a condenser and an absorption column integrated in the internal gas circuit as shown in the drawing was used. Into a passivated tubular reactor with a working volume of 15 liters was introduced 19 kg of a molten mixture comprising 35% by weight of DCAA and 65% by weight of MCAA. The reaction pump was started and 0.032 kg of a commercially available palladium on carbon catalyst (5% Pd on carbon) was added through the catalyst launder. Start the combined HCl absorption system filled with water. The reactor was flushed with hydrogen and the reaction mixture was heated to 155°C. The tubular reactor was pressurized with hydrogen to 3 bar and the hydrogenation was started by supplying hydrogen at a controlled pressure. During the reaction, the reactor headspace gas, consisting mainly of hydrogen chloride and hydrogen gas, is continuous...

Embodiment 2

[0035] Hydrogenation of a mixture containing 3.0% by weight dichloroacetic acid

[0036] The same reactor as in Example 1 was used to hydrogenate a mixture comprising 3.0% by weight DCAA, 95.4% by weight MCAA and 1.2% by weight acetic acid. 19 kg of the molten mixture having the abovementioned composition were introduced into the passivated tubular reactor. The reaction pump was started and 0.019 kg of a commercially available palladium on carbon catalyst (5% Pd on carbon) was added through the catalyst launder. Start the combined HCl absorption system filled with water. The reactor was flushed with hydrogen, then the reaction mixture was heated to 150°C. The tubular reactor was pressurized with hydrogen to 3 bar and the hydrogenation was started by supplying hydrogen at a controlled pressure. During the reaction, the reactor headspace gas, consisting mainly of hydrogen chloride and hydrogen gas, is continuously passed through an internal absorption system where hydrogen ch...

Embodiment 3

[0038] Hydrogenation of a mixture containing 4.0% by weight dichloroacetic acid at ambient conditions

[0039] The same reactor as in Example 1 was used to hydrogenate a mixture comprising 4.0% by weight DCAA, 93.1% by weight MCAA, 2.5% by weight acetic acid and 0.4% by weight water. 19 kg of the molten mixture having the abovementioned composition were introduced into the passivated tubular reactor. The reaction pump was started and 0.076 kg of a commercially available palladium on carbon catalyst (5% Pd on carbon) was added through the catalyst launder. Start the combined HCl absorption system filled with water. The reactor was flushed with hydrogen, then the reaction mixture was heated to 145°C. The hydrogenation was started by supplying hydrogen at a controlled pressure. Keep the pressure constant at 0-0.2 bar. During the reaction, the reactor headspace gas, consisting mainly of hydrogen chloride and hydrogen gas, is continuously passed through an internal absorption s...

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PUM

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Abstract

The present invention describes a process for the manufacture of substantially pure monochloroacetic acid from a liquid chloroacetic acid mixture comprising monochloroacetic acid and dichloroacetic acid, in particular in an amount of 2 to 40 percent by weight, wherein said mixture, further mixed with a suspended hydrogenation catalyst, is mixed with hydrogen gas and the resulting mixture is brought to reaction in a reactor, which is characterized in that the reactor is a loop reactor comprising a gas and liquid recirculation system coupled via an ejector mixing nozzle, in which reactor the gas and liquid are circulated in co-current flow, and the mixing intensity introduced to the liquid phase is at least 50 W/l of liquid phase.

Description

technical field [0001] The present invention relates to the preparation of highly pure monochloroacetic acid (MCCA), in particular to the preparation of monochloroacetic acid and a large amount of dichloroacetic acid (DCCA) (for example 2-20% by weight) (and in the case also trichloroacetic acid) Preparation of high-purity monochloroacetic acid from liquid mixture. Background technique [0002] Monochloroacetic acid is required for the synthesis of many basic chemicals, especially in the pharmaceutical or cosmetic industries. Monochloroacetic acid is generally produced on an industrial scale by direct chlorination of acetic acid, however, the reaction inevitably leads to crude products containing, in addition to the desired monochloroacetic acid, also large amounts of dichloroacetic acid and trichloroacetic acid (sometimes) and residual acetic acid . In particular it was found that it was practically impossible to eliminate the formation of the troublesome by-product dichl...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C51/377C07C53/16
CPCC07C51/377C07C53/16
Inventor R·史托尼斯库提姆曼斯G·凯顿贝兹
Owner BUSS CHEMTECH
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