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Preparation method of 2-methyl-4-acetoxy-2-butenal with thermal stability

A technology of acetoxy and thermal stability, which is applied in the field of preparation of 2-methyl-4-acetoxy-2-butenal, can solve the problem of large loss, high content and affecting the effective yield of vitamin A synthesis reaction Physiological activity of vitamin A products and other issues to achieve the effect of improving quality

Active Publication Date: 2021-11-05
WANHUA CHEM GRP CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0018] One of the main disadvantages of 2-methyl-4-acetoxy-2-butenal prepared by the existing process is the heat-sensitive cis-2-methyl-4-acetoxy-2-butene in the product The content of aldehyde is high, and the loss in the rectification separation process is relatively large
In addition, the downstream of 2-methyl-4-acetoxy-2-butenal is mainly used in the synthesis of vitamin A to produce 2-methyl-4-acetoxy-2-butenal containing cis isomer The process of vitamin A synthesized as raw material will produce more isomers of 11-cis vitamin A, which seriously affects the effective yield of vitamin A synthesis reaction and the physiological activity of vitamin A products

Method used

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  • Preparation method of 2-methyl-4-acetoxy-2-butenal with thermal stability
  • Preparation method of 2-methyl-4-acetoxy-2-butenal with thermal stability
  • Preparation method of 2-methyl-4-acetoxy-2-butenal with thermal stability

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0059] Weigh 120kg xylene (active hydrogen content is 46mgKOH / kg in terms of hydroxyl value), 1000g 5%Pt / Al 2 o 3 Add the catalyst into a 500L bubbling kettle, raise the temperature to 90°C, add 40kg of the raw material 2-methylene-4-acetoxybutyraldehyde to the reaction kettle, and feed 200L / min Mixed gas (3%H 2 / 97%N 2 ) to start the reaction; after 6 hours of reaction, the temperature was lowered to 30° C. to stop the reaction, and the conversion rate of raw materials was measured to be 95.0%, the selectivity of trans-2-methyl-4-acetoxy-2-butenal was 83%, and the selectivity of cis The selectivity of 2-methyl-4-acetoxy-2-butenal is 0.8%; after the catalyst is filtered, the reaction solution is sequentially passed through the continuous solvent removal tower, by-product removal tower, raw material removal tower, and product tower separation system Solvent, hydrogenation by-products, unreacted raw material 2-methylene-4-acetoxybutyraldehyde, heavy components, product 2-meth...

Embodiment 2

[0063] Weigh 80kg toluene (the active hydrogen content is 15mgKOH / kg in terms of hydroxyl value), 890g 4.5%Pt / Al 2 o 3 Add the catalyst into a 500L bubbling kettle, raise the temperature to 50°C, add 40kg of the raw material 2-methylene-4-acetoxybutyraldehyde to the reaction kettle, and feed 89L / min Mixed gas (4%H 2 / 96%N 2 ) to start the reaction; after 7 hours of reaction, the temperature was lowered to 30° C. to stop the reaction, and the conversion rate of raw materials was measured to be 63%, the selectivity of trans 2-methyl-4-acetoxy-2-butenal was 92.7%, and the cis-2 - The selectivity of methyl-2-butenal is 0.8%; after the catalyst is filtered, the reaction solution passes through the solvent removal system, the by-product removal tower, the raw material removal tower, the product tower, and the hydrogenation by-product successively. The product, unreacted raw material 2-methylene-4-acetoxybutyraldehyde, heavy components, and the product 2-methyl-4-acetoxy-2-butenal...

Embodiment 3

[0067] Weigh 100kg toluene (the active hydrogen content is 27.3mgKOH / kg in terms of hydroxyl value), 800g 8%Pd / Al 2 o 3 Add the catalyst into a 500L bubbling kettle, raise the temperature to 90°C, add 40kg of the raw material 2-methylene-4-acetoxybutyraldehyde to the reaction kettle, and feed 200L / min Mixed gas (6%H 2 / 94%N 2 ) to start the reaction; after 4 hours of reaction, the temperature was lowered to 30° C. to stop the reaction, and the conversion rate of raw materials was measured to be 72%, the selectivity of trans-2-methyl-4-acetoxy-2-butenal was 93.1%, and the selectivity of cis The selectivity of 2-methyl-2-butenal is 0.8%. After the catalyst is filtered, the reaction solution passes through the solvent removal system, the solvent removal tower, the by-product removal tower, the raw material removal tower, and the product tower successively. By-products, unreacted raw materials 2-methylene-4-acetoxybutyraldehyde, heavy components, the yield of product 2-methyl-4...

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Abstract

The invention discloses a preparation method of 2-methyl-4-acetoxy-2-butenal with thermal stability, which comprises the following steps: (1) carrying out gas-solid-liquid three-phase hydroisomerization reaction on 2-methylene-4-acetoxybutyraldehyde and a solvent under the action of a catalyst to generate 2-methyl-4-acetoxy-2-butenal; (2) after the reaction reaches a specified conversion rate, terminating the reaction, conducting cooling and filtering out the catalyst; and (3) rectifying and separating the solvent, hydrogenation by-products and unreacted raw materials in the system to obtain the product 2-methyl-4-acetoxy-2-butenal. In the step (1), active hydrogen in the used solvent is controlled to be less than or equal to 100mgKOH / kg in terms of hydroxyl value content. The 2-methyl-4-acetoxy-2-butenal provided by the invention is good in thermal stability, low in loss rate in a rectification separation process and low in cis-isomer content, and can better meet downstream requirements.

Description

technical field [0001] The invention relates to a preparation method of 2-methyl-4-acetoxy-2-butenal with thermal stability, belonging to the field of chemical intermediate preparation. Background technique [0002] 2-Methyl-4-acetoxy-2-butenal is an important intermediate in the synthesis of vitamin A. Due to the importance of 2-methyl-4-acetoxy-2-butenal in the synthesis of vitamin A industry, the synthesis process of 2-methyl-4-acetoxy-2-butenal has been a long-standing Research hotspots. [0003] At present, the preparation process of 2-methyl-4-acetoxy-2-butenal is known, and the advantages or disadvantages of various routes are discussed in detail in the literature. [0004] Patent US5453547 discloses a synthetic route for the preparation of five-carbon aldehyde using dimethoxyacetone as the starting material. The reaction formula is as follows: dimethoxyacetone reacts with acetylene and hydrogen to form compound 2, and compound 2 reacts with acetic anhydride to form...

Claims

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Application Information

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IPC IPC(8): C07C69/145C07C67/28C07C67/54
CPCC07C67/28C07C67/54C07C69/145Y02P20/584
Inventor 程晓波吕英东张涛林龙张旭翟文超
Owner WANHUA CHEM GRP CO LTD
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