Method for preparing trimethylacetaldehyde

Abstract

The invention discloses a method for preparing trimethylacetaldehyde. The method comprises the following steps: (1) firstly, carrying out a reduction reaction, namely taking pivaloyl chloride as a rawmaterial, palladium-carbon as a catalyst, acetonitrile as a reaction solvent and N,N-diisopropylethylamine as an acid-binding agent, and carrying out a reduction reaction with hydrogen; (2) secondly,carrying out filtration after the reduction reaction, namely filtering reaction liquid to obtain filtrate and a palladium-carbon catalyst, dissolving the generated organic salt into a solvent, and recycling the palladium-carbon catalyst; and (3) finally, carrying out distillation, namely distilling the filtrate, and collecting a fraction at 76-78 DEG C to obtain a trimethylacetaldehyde product, wherein the yield of the trimethylacetaldehyde product is up to 73%, and the content is greater than 98%. According to the method, common Pa / C available in the market is adopted to replace quinoline-sulfur poisoned Pa / C as a catalyst, organic tertiary amine is adopted as the acid-binding agent, and acetonitrile, DMF (Dimethyl Formamide) and lower fatty acid are adopted as solvents to replace aromatic solvents such as methylbenzene and the like, so that reaction steps and later treatment steps are simple.

Description

technical field [0001] The invention relates to the technical field of pivalaldehyde preparation, in particular to a preparation method of pivalaldehyde. Background technique [0002] Pivalaldehyde is an important organic chemical intermediate. At present, there are mainly the following methods for its synthesis: [0003] 1. Document Bull.Soc.Chim.Belg., 1992, 101(9):817-819, using Grignard reagent formylation to prepare pivalaldehyde. Its reaction formula is as follows: [0004] [0005] Since the preparation and reaction of the Grignard reagent requires strict control of the reaction conditions, the product yield is only 57% to 61%, and the cost of raw materials is relatively expensive, so the production cost will be too high. [0006] 2. Documents J.Am.Chem.Soc,.1964,86(6):1085-1089, etc., use pivalonitrile as raw material to produce pivalaldehyde by reductive hydrolysis. Its reaction formula is as follows: [0007] [0008] Although this step reaction product y...

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Problems solved by technology

[0014] This method has a high yield, but there are problems that the generated salt compound is insoluble in the solvent, which leads to poor separation of the catalyst and the salt compound, and troublesome catalyst recovery and treatment, and the reaction solution needs to be filtered, washed, extracted, dried, and rectified. In order to get the product, the steps are relatively cumbersome

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