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Continuous gas phase reaction method of isoprene-3-methyl butan-2-alkenyl ether

A technology of isoprenyl and alkenal diisoprenyl acetal is applied in the field of preparation of isoprenyl-3-methylbut-2-enyl ether, and can solve the requirement of phosphoric acid concentration control High, poor stability, difficulty and other problems, to reduce the operation of solvent recovery, improve the yield, and achieve the effect of less destructive

Inactive Publication Date: 2009-03-11
ZHEJIANG UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The above-mentioned process has high requirements for the control of phosphoric acid concentration, is difficult, has poor stability, and is difficult to implement in production

Method used

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  • Continuous gas phase reaction method of isoprene-3-methyl butan-2-alkenyl ether
  • Continuous gas phase reaction method of isoprene-3-methyl butan-2-alkenyl ether
  • Continuous gas phase reaction method of isoprene-3-methyl butan-2-alkenyl ether

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] Example 1 Preparation of 3-methylbut-2-enal di-isoprenyl acetal

[0033] In a 1000ml three-neck flask equipped with mechanical stirring, a 1.0m rectification tower (20 theoretical plates of the rectification tower), a water separator, and a thermometer, 100ml of cyclohexane was put in, and 3-methyl-2-butyl Alkenal 168g (2mol), 3-methyl-2-butenol 361g (4.2mol), adipic acid 5g, heat up and reflux, control the reaction temperature at 80-85°C, and separate the generated water in the water separator After 10 hours of reaction, the reaction was terminated, unreacted raw materials were recovered by distillation under reduced pressure, and then rectified under reduced pressure to obtain 296 g of 3-methylbut-2-enal di-prenyl acetal, with a content of 97%.

Embodiment 2

[0034] Embodiment 2 Preparation of Elimination Reaction Catalyst

[0035] 2 parts of calcium phosphate, 3 parts of diammonium hydrogen phosphate, 1 part of potassium dihydrogen phosphate, and 3 parts of graphite (parts by weight) are mixed evenly, pressed into tablets, baked at 250-280°C for 3 hours in an isolated air, crushed, sieved, and selected The 30-80 mesh sieve is used as the catalyst for elimination.

Embodiment 3-5

[0036] Example 3-5 Preparation of isoprenyl-3-methylbut-2-enyl ether

[0037]Use a reaction device with a gas-phase fixed-bed reactor, a 1.5m rectifying tower, and a 500ml reactor. The rectifying tower has a theoretical plate number of 30, and there is a side outlet at 15 plates from the bottom of the tower. The gas phase pipe at the top of the bed reactor leads to the bottom of the rectification tower, and the gas inlet is 1 plate away from the bottom of the rectification tower; Alkenyl acetal realizes accurate feeding; In the fixed-bed reactor, the catalyst prepared in embodiment 2 is loaded earlier, and 200g (content 97%) of 3-methylbut-2-enal diisoprene is dropped into the reactor Alkenyl acetal; pull vacuum at the top of the rectification tower, control 200-300MPa (absolute pressure); preheat the fixed bed to 200-250°C; heat up the reaction kettle, after heating to 140-150°C -2-enal diisoprenyl acetal is vaporized and enters the fixed bed reactor for reaction, the reacti...

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Abstract

The invention discloses a method for preparing an intermediate prenyl-3-methylbutyl-2-alkenyl ester. The prior methods have high control requirement on the concentration of a phosphoric acid catalyst, which have large difficulty and poor stability, and are hard to carry out in production; and other methods have low yield and conversion ratio. The method has the following steps: feeding 3-methylbutyl-2-olefine aldehyde di-prenyl acetal from a reaction kettle; performing a catalytical elimination reaction in a gas-phase fixed-bed reactor after vaporization to obtain mixed gas; introducing the mixed gas into a rectification tower; recovering the mixture at the top of the rectification tower to obtain 3-methyl-2-butenol; and discharging the material from one side of the rectification tower to obtain the prenyl-3-methylbutyl-2-alkenyl ester, wherein the unreacted raw material 3-methylbutyl-2-olefine aldehyde di-prenyl acetal at the bottom of the rectification tower is refilled into the reaction kettle for vaporization and continuous reaction, and the reaction kettle is replenished with new raw materials continuously. The catalyst used in the method has smaller destructive effect, reduces the quantity of leftover materials after the elimination reaction, and has high selectivity.

Description

technical field [0001] The invention relates to a method for preparing perfume and pharmaceutical intermediate isoprenyl-3-methylbut-2-enyl ether. Background technique [0002] Prenyl-3-methylbut-2-enyl ether, a precursor for the synthesis of citral, isoprenyl-3-methylbut-2-enyl ether via Claisen rearrangement and Cope rearrangement Get citral. Citral is a kind of food and daily chemical fragrance. Citral can be used as raw material to synthesize citronil and damascenone fragrances; it can also synthesize β-ionone, and then produce vitamin A and β-carotene. [0003] The structural formula of prenyl-3-methylbut-2-enyl ether is as follows: [0004] [0005] The synthesis of isoprenyl-3-methylbut-2-enyl ether is based on 3-methylbut-2-enal di-isoprenyl acetal, after eliminating a molecule of 3-methyl -2-butenol to give prenyl-3-methylbut-2-enyl ether. [0006] [0007] At present, isoprenyl-3-methylbut-2-enyl ether mainly has the following synthetic methods: [0008]...

Claims

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Application Information

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IPC IPC(8): C07C43/16C07C41/01
CPCY02P20/584
Inventor 商志才钱洪胜吕叔敏赵晓东王昌泽
Owner ZHEJIANG UNIV
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