3-methylcrotonaldehyde synthesis process

Abstract

The invention provides a 3-methylcrotonaldehyde synthesis process. A metal oxide is adopted as a catalyst, in the presence of aids, 2-methyl-3-butyne-2-alochol is adopted as a raw material for catalytic rearrangement to prepare 3-methylcrotonaldehyde. The process is high in catalysis efficiency, good in selectivity and applicable to industrial production, and the yield is as high as 93.9-96.1. Thecatalyst used in the process is low in price and small in amount, so that the production cost can be reduced; the catalysis system of the process is simple, later separation steps can be simplified,and energy consumption and cost can be reduced; the process is rapid in conversion speed, and the reaction time only needs 20-40 minutes; the catalyst used in the process is good in stability, high performance can be still maintained after multiple batches of mechanically application, and the yield is reduced by 0.94% after 20 times of mechanically application.

Description

technical field [0001] The invention belongs to the technical field of organic chemical industry and relates to a synthesis process of prenaldehyde. Background technique [0002] Prenal, 3-methyl-2-butenal, is a colorless liquid. It is mainly used as an intermediate for the production of various fine chemical products and pharmaceuticals such as citral, vitamin E and vitamin A. [0003] According to the difference of reaction raw materials, there are three main synthetic routes of prenal. [0004] Prenol as raw material: In DE-2517859, a tubular reactor is used at 150-300°C in an atmosphere of excess oxygen to catalyze the oxidation of prenol to prenal by copper, and the reaction produces more by-products. Less selective. JP-60 / 246340 reported that using a silver and copper composite catalyst loaded on a carrier, at 400-500 ° C, prenol is oxidized by oxygen to prepare prenal, with a selectivity of 96%, but high temperature and high temperature are required. The conversio...

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Problems solved by technology

CN101709026A adopts 2,2,6,6-tetramethylpiperidine nitroxide free radical compound as catalyst, nitrate as auxiliary agent, oxygen-containing gas as oxidant, catalyzes the oxidation of isopentene in organic solvent at room temperature or under heating conditions Alcohol synthesis of prenaldehyde, the yield can reach 92.3%, but the price of the catalyst is high, it cannot be reused and the reaction time is long (>6h)

[0006] 3-methyl-3-butene-1 alcohol as raw material: In US4192820, the catalytic oxidation and rearrangement reaction are combined to operate, and 3-methyl-3-butene-1 alcohol is catalyzed on silver crystals or silver-loaded Oxidation (at the same time as catalytic oxidation, it has been partially rearranged into prenaldehyde), the mixture is rearranged with acid or alkali, the selectivity can be stabilized at about 91%, but the reaction temperature is 400-460 ° C and the alcohol content is relatively high 52% lower conversion rate

[0008] 2-methyl-3-butyn-2-alcohol is raw material: Tetrahedron Letters, 1988,29,6253 will 2-methyl-3-butyn-2-alcohol, tetrabutoxytitanium, cuprous chloride and p-toluenesulfonic acid reacted in o-dichlorobenzene to obtain prenal, the reaction time was 1h, and the yield was 83%. This reaction used the toxic solvent o-dichlorobenzene, and increased the separation cost

CN101381292B adopts a composite catalyst composed of titanium acetylacetonate, cuprous chloride and benzoic acid to realize the continuous production of 2-methyl-3-butyn-2-alcohol to prenal through reactive distillation coupling technology, comprehensive The yield can reach 88-93%, but the price of the catalyst is high and it is difficult to recycle and apply

[0011] (1) The price of the catalyst is relatively high;

[0012] (2) Long reaction time;

[0013] (3) The yield of prenaldehyde is low;

[0014] (4) It is difficult to recover and apply the catalyst;

[0015] (5) Use of highly toxic solvents

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