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Method for synthesizing trans-2-hexenal

A technology of hexenal and reaction formula, applied in the field of synthesizing trans-2-hexenal, can solve the problems of unavailable raw materials, low reaction yield, high price, etc., achieve a recyclable environment, easy separation and recovery, low cost effect

Active Publication Date: 2018-11-06
JIANGSU YANGNONG CHEM GROUP +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0007] Among the above synthetic routes, the raw materials used in route one are not easy to obtain, the price is expensive, and the reaction process is prone to excessive oxidation, the reaction selectivity is poor, and subsequent separation is difficult; the raw materials used in route two are easy to obtain, but the reaction yield is low, and a fluorine-containing catalyst is used in the reaction. Produces fluorine-containing wastewater, which is difficult to treat

Method used

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  • Method for synthesizing trans-2-hexenal
  • Method for synthesizing trans-2-hexenal
  • Method for synthesizing trans-2-hexenal

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] Add 15g ionic liquid [(CH 2 ) 3 SO 3 HMIM][HSO 4 ], 500g of vinyl ethyl ether and 1100g of n-butyraldehyde mixed solution was added dropwise at 25°C, stirred and reacted at 45°C for 1 hour after the dropwise addition, vacuum distillation after the reaction was completed, the water pump pressure was -0.1Mpa, the kettle temperature was 130°C, and the temperature At 125°C, 1582g of fractions were collected, the content of intermediate A was 84.3%, and the yield was 95.1%. The recovered ionic liquid catalyst weighed 16g in the still material.

[0027] Add 3164g of 0.5% dilute sulfuric acid solution and 1582g of the above-mentioned intermediate A with a content of 84.3% to the reaction bottle, and set up a reflux oil-water stratification device. Heating and normal pressure distillation, oil and water in the water separator are separated, the oil layer is recovered on the upper side and enters the oil layer receiving bottle, and the water layer is returned to the reaction ...

Embodiment 2

[0030] Add 10g ionic liquid [(CH 2 ) 3 SO 3 HMIM][CF 3 SO 3 ], 500g of vinyl ether and 1500g of n-butyraldehyde mixed solution was added dropwise at 0°C, after the dropwise addition was completed, the temperature was raised to 20°C and stirred for 6 hours, and after the reaction was completed, distillation under reduced pressure was carried out. The pressure of the water pump was -0.1Mpa, and the temperature of the kettle was 130°C. The temperature was 125° C., 1986 g of fractions were collected, the content of intermediate A was 69.3%, and the yield was 98.1%. The recovered ionic liquid catalyst weighed 11 g in the still material.

[0031] Add 397g of 25% dilute sulfuric acid solution and 1986g of the above-mentioned intermediate A with a content of 69.3% to the reaction bottle, and set up a reflux oil-water stratification device. Heating and normal pressure distillation, oil and water in the water separator are separated, the oil layer is recovered on the upper side and ...

Embodiment 3

[0034] Add 0.5 g ionic liquid [(CH 2 ) 3 SO 3 HMIM][CF 3 SO 3 ], 500g of vinyl ethyl ether and 2500g of n-butyraldehyde mixed solution was added dropwise at 15°C, after the dropwise addition was completed, the temperature was raised to 35°C and the reaction was stirred for 3 hours, and after the reaction was completed, distillation under reduced pressure was carried out. The pressure of the water pump was -0.1Mpa, and the temperature of the kettle was 130°C. The temperature was 125°C, 2995g of fractions were collected, the content of intermediate A was 20.9%, and the yield was 92.0%. The recovered ionic liquid catalyst weighed 0.6g in the still material.

[0035] Add 1000g of 5% dilute sulfuric acid solution and 2995g of the above-mentioned intermediate A with a content of 20.9% to the reaction flask, and set up a reflux oil-water stratification device. Heating and atmospheric pressure distillation, oil and water in the water separator are separated, the oil layer is recov...

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Abstract

The invention discloses a method for synthesizing trans-2-hexenal. The method includes steps of (1), adding acidic ionic liquid into reaction flasks, completely dropwise adding vinyl ethyl ether and butyraldehyde mixed liquid into the reaction flasks at the temperatures of 0-25 DEG C, then heating systems until the temperatures of the systems reach 20-45 DEG C, carrying out stirring reaction for 1-6 hours, and carrying out reduced pressure distillation after the reaction is completely carried out so as to obtain cyclization intermediates A; adding dilute sulfuric acid aqueous solution and theintermediates A into reaction flasks, erecting reflux oil and water layering devices, carrying out heating normal-pressure distillation for 4-48 hours, and extracting upper oil layers into oil layer receiving flasks; (3), rectifying and purifying hexenal crude products, carrying out normal-pressure rectification to obtain substances with low boiling points and then carrying out reduced pressure rectification to obtain the trans-2-hexenal. A molar ratio of butyraldehyde to vinyl ethyl ether is 2:1-5:1, and the usage of the acidic ionic liquid accounts for 0.1-5% of the total weight of the vinylethyl ether; the acidic ionic liquid is [(CH2)3SO3HMIM][HSO4] or [(CH2)3SO3HMIM][CF3SO3]. The oil layers are the hexenal crude products; the mass concentration of the dilute sulfuric acid aqueous solution is 0.5-25%, and a weight ratio of the dilute sulfuric acid aqueous solution to the intermediates A is 0.2:1-2:1. The method has the advantages of environmental protection, low cost and high yield.

Description

technical field [0001] The invention belongs to the field of organic synthesis, in particular to a method for synthesizing trans-2-hexenal. Background technique [0002] Trans-2-hexenal is one of the main components of the unique fragrance of green plants. Its fragrance presents green, aldehyde, fruity, spicy, fatty, etc. Before it is diluted, the fragrance is strong and strong. Spikes, after dilution, have a pleasant green leaf fragrance and fruity aroma. It is a food spice approved by my country's GB2760-1996. It can be used to prepare citrus, apple, strawberry, berry, tea and other food flavors. At the same time, trans- 2-hexenal is also an important intermediate in organic synthesis. Natural trans-2-hexenal is expensive and exists in a small amount, and is usually prepared by chemical synthesis. Trans-2-hexenal is a colorless oily liquid, hardly soluble in water, easily soluble in organic solvents such as ethanol, volatile, easy to oxidize under high temperature conditio...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C45/60C07C47/21
CPCC07B2200/09C07C45/60C07D323/04C07C47/21
Inventor 丁克鸿徐林朱叶峰王怡明王根林刘补娥孙伟顾峰
Owner JIANGSU YANGNONG CHEM GROUP
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