Method for preparing 4-acetoxy-2-methyl-2-crotonaldehyde

A technology of butyraldehyde and hydroxybutyraldehyde, which is applied in the field of preparation of 4-acetoxy-2-methyl-2-butenal, can solve problems such as high price, achieve less waste water, be environmentally friendly, and avoid phosphine Effects of the use of catalysts

Active Publication Date: 2019-08-20
WANHUA CHEM GRP CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

But this method needs to use expensive rhodium series catalyst and palladium metal catalyst

Method used

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  • Method for preparing 4-acetoxy-2-methyl-2-crotonaldehyde
  • Method for preparing 4-acetoxy-2-methyl-2-crotonaldehyde
  • Method for preparing 4-acetoxy-2-methyl-2-crotonaldehyde

Examples

Experimental program
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Effect test

Embodiment 1

[0050] (1) Preparation of 2-methylene-4-hydroxybutyraldehyde:

[0051] Add 1L tetrahydrofuran into a 3L glass three-neck flask, turn on the mechanical stirring, set the speed at 800rpm, cool down to -30°C, then add 2mol n-butyllithium and 2.5mol diisopropylamine to it, react for 0.5h, add 4-hydroxybutyl Add 1 mol of aldehyde, stir for 0.5 h, add 1 mol of (N,N-dimethyl)methylene ammonium iodide, and react at room temperature for 8 h. After the reaction is over, add 0.5 L of water to the system, extract three times with dichloromethane, 0.5 L each time, combine the organic phases, reclaim the dichloromethane under reduced pressure, and rectify the mother liquor under the condition of 1kPa with a packed column with a theoretical plate number of 20. The reaction solution after removing the solvent, the reflux ratio is 2:1, collect the distillate at 38-39°C at the top of the tower to obtain 2-methylene-4-hydroxybutyraldehyde, and analyze 2-methylene-4-hydroxybutyraldehyde by gas ch...

Embodiment 2

[0057] (1) Preparation of 2-methylene-4-hydroxybutyraldehyde:

[0058] Add 1L of toluene to a 3L glass three-neck flask, turn on mechanical stirring, set the speed at 800rpm, cool down to -40°C, then add 1.5mol of n-butyllithium and 2mol of diisopropylamine to it, react for 1h, then add 4-hydroxybutyraldehyde 1mol, stirred for 1h, added (N,N-dimethyl) methylene ammonium iodide 1mol, then reacted at room temperature for 6h. After the reaction is over, add 0.5 L of water to the system, extract three times with dichloromethane, 0.5 L each time, combine the organic phases, reclaim the dichloromethane under reduced pressure, and rectify the mother liquor under the condition of 1kPa with a packed column with a theoretical plate number of 20. The reaction solution after removing the solvent, the reflux ratio is 2:1, collect the distillate at 38-39°C at the top of the tower to obtain 2-methylene-4-hydroxybutyraldehyde, and analyze 2-methylene-4-hydroxybutyraldehyde by gas chromatograp...

Embodiment 3

[0064] (1) Preparation of 2-methylene-4-hydroxybutyraldehyde:

[0065] Add 1.5L tetrahydrofuran to a 3L flask, start stirring, set the speed at 800rpm, cool down to -10°C, then add 3mol n-butyl lithium and 2.5mol diisopropylamine to it, react for 2.5h, then add 1mol of 4-hydroxybutyraldehyde , stirred for 2.5h, added (N,N-dimethyl) methylene ammonium iodide 1.5mol, and then reacted at room temperature for 12h. After the reaction is over, add 0.5 L of water to the system, extract three times with dichloromethane, 0.5 L each time, combine the organic phases, reclaim the dichloromethane under reduced pressure, and rectify the mother liquor under the condition of 1kPa with a packed column with a theoretical plate number of 20. The reaction solution after removing the solvent, the reflux ratio is 2:1, collect the distillate at 38-39°C at the top of the tower to obtain 2-methylene-4-hydroxybutyraldehyde, and analyze 2-methylene-4-hydroxybutyraldehyde by gas chromatography The aldeh...

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Abstract

The invention discloses a method for preparing 4-acetoxy-2-methyl-2-crotonaldehyde, and provides a preparation method of five-carbon aldehyde which is an important intermediate of vitamin A. The method comprises the steps: (1) performing a reaction between 4-hydroxybutanal and (N, N-dimethyl) methylene ammonium iodide so as to produce 2-methylene-4-hydroxybutanal; (2) isomerizing 2-methylene-4-hydroxybutanal so as to obtain 4-hydroxy-2-methyl-2-crotonaldehyde; and (3) performing a reaction between 4-hydroxy-2-methyl-2-crotonaldehyde and acetic anhydride so as to obtain 4-acetoxy-2-methyl-2-crotonaldehyde (five-carbon aldehyde). According to the method, 4-hydroxybutanal which is adopted as a starting material is a common fine chemical intermediate, and is cheap and easily available, the method has a short reaction synthesis route, a high reaction yield, low cost, simple operation and little pollution to the environment, and an effective synthetic route is provided.

Description

technical field [0001] The invention belongs to the field of synthesis of chemical intermediates, and in particular relates to a preparation method of 4-acetoxy-2-methyl-2-butenal. Background technique [0002] 4-Acetoxy-2-methyl-2-butenal (hereinafter referred to as "penta-carbon aldehyde") is an important intermediate for the synthesis of vitamin A. Due to the importance of five-carbon aldehyde in the synthesis of vitamin A industry, the synthesis process of five-carbon aldehyde has been a research hotspot for a long time. [0003] 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 Compound 3, compound 3 was isomerized under the action of Cu catalyst to obtain compound 4, and compound 4 was hydrolyzed to finally obtain five-carbo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C69/145C07C67/297
CPCC07C67/16C07C45/68C07C45/67C07C69/145C07C47/263
Inventor 翟文超程晓波林龙朱龙龙张旭杨宗龙李莉宋军伟刘英瑞郭劲资王延斌吕英东张涛黎源
Owner WANHUA CHEM GRP CO LTD
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