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Method for preparation of citral

A technology of citral and inhibitors, which is applied in the field of preparation of citral, can solve the problems of violent heat release, side reactions, and difficulty in removing reaction heat from the reactor, and achieve enhanced heat and mass transfer effects, high selectivity, and shortened side reactions the effect of time

Active Publication Date: 2017-07-25
WANHUA CHEM GRP CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the defects that still exist in this method are: 1. The rearrangement process is violently exothermic, and it is difficult to remove the heat of reaction in a general reactor, and safety accidents are likely to occur in the actual production process
2. When the system contains alcohols, there will be obvious side reactions

Method used

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  • Method for preparation of citral

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] Embodiment 1 The preparation of cis / trans-isopentenyl-3-methylbutadiene ether

[0026] Add 774g prenol (about 9mol), 84g prenaldehyde (about 1mol) and 1.15g phosphoric acid (mass content 85%, about 0.01mol) into the bottom of the rectification column, the number of theoretical plates of the rectification column is 9 , the temperature at the bottom of the tower is 110°C, the vacuum at the top of the tower is 5KPa, and the reflux ratio is 1:10. Prenyl alcohol and water are extracted at the top of the tower. After heating the tower kettle for 5 hours, when there is almost no reflux at the top of the tower, stop heating. The product obtained in the tower kettle is isopentenyl prenyl aldehyde, and the acetal content is 99% as detected by the gas phase. Raise the temperature of the tower kettle to 150°C, the vacuum at the top of the tower is 2KPa, the reflux ratio is 1:3, and the cis / trans-prenyl-3-methylbutadiene ether and isopentenol are produced at the top of the tower . ...

Embodiment 2

[0028]The length of the microreactor preheating tube is 0.5m, the inner diameter is 1mm, and the temperature of the external constant temperature circulating bath of the preheating pipeline is 180°C. The temperature of the external constant temperature circulating bath of the microreactor is 200°C, and the temperature of the external constant temperature circulating bath of the micro heat exchanger is 120°C. The length of the delay line is 6m and the inner diameter is 4mm. The temperature of the constant temperature circulating bath outside the delay pipeline is 180°C. Feed the raw materials (cis / trans-prenyl-3-methylbutadiene ether mass content 97%, prenol content 2.5%) through the preheating pipeline at a rate of 15mL / min, formic acid The tert-butyl ester is pumped into the microreactor simultaneously with the raw material in the amount of 0.5mol% of the raw material, and flows through the micro heat exchanger and the delay pipeline (the pressure behind the micro heat excha...

Embodiment 3

[0030] The length of the preheating tube of the micro heat exchanger is 0.5m, the inner diameter is 1mm, the temperature of the external constant temperature circulating bath of the preheating pipeline is 200°C, the reaction liquid directly enters the micro heat exchanger, and the temperature of the external constant temperature circulating bath of the micro heat exchanger is 150°C. The length of the delay line is 6m and the inner diameter is 4mm. The temperature of the constant temperature circulating bath outside the delay pipeline is 180°C. Feed the raw materials (cis / trans-prenyl-3-methylbutadiene ether mass content 97%, prenol content 2.5%) through the preheating pipeline at a rate of 20mL / min, acetic acid The tert-butyl ester is pumped into the micro heat exchanger at the same time as the raw material in the amount of 2.0mol% of the raw material, and then enters the delay pipeline (the pressure after the micro heat exchanger will be 0.2MPa, and the reaction solution stay...

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Abstract

The invention provides a method for preparation of citral. The method comprises that cis / trans-isopentenyl-3-methyl butadiene ether is subjected to Claisen rearrangement to form 2, 4, 4-trimethyl-3-formyl-1, 5-hexadiene, and the 2, 4, 4-trimethyl-3-formyl-1, 5-hexadiene is subjected to Cope rearrangement to form citral (3, 7-dimethyl-2, 6-octadien-1-aldehyde). The method utilizes an ester as a side reaction inhibitor to adjust a reaction rate. The method has high selectivity, a fast reaction rate and whole process residence time of 1-15min.

Description

technical field [0001] The invention relates to a method for preparing citral. Claisen rearrangement of cis / trans-prenyl-3-methylbutadiene ether as starting material to obtain 2,4,4-trimethyl-3-formyl-1,5-hexanedi ene, followed by a Cope rearrangement to give citral (3,7-dimethyl-2,6-octadiene-1-al). Background technique [0002] Citral is not only a commonly used fragrance product itself, but also can be used as a raw material for various fine chemicals. Its downstream products include vitamins, precious spices and so on. In the U.S. published patent US4288636, there is an introduction about the preparation of citral intermediate product cis / trans-isopentenyl-3-methyl butadiene ether, which uses prenyl prenyl aldehyde to obtain a A molecule of prenyl-3-methylbutadiene ether and a molecule of prenyl alcohol, the prenyl alcohol is continuously distilled to obtain cis / trans-prenyl-3-methylbutadiene ether . Citral can be prepared by rearrangement reaction of cis / trans-pren...

Claims

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Application Information

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IPC IPC(8): C07C45/67C07C47/21
CPCC07C45/513C07C45/67C07C47/21
Inventor 鲍元野张静王亚新李广琼孙钦鹤代红涛宗芳崔乾张永振黎源
Owner WANHUA CHEM GRP CO LTD
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