Method for preparing whisky lactone

Abstract

This invention provides a method for preparing whiskey lactone. The method comprises: (1) reacting n-valeraldehyde and crotonic acid by free radical addition under N2 protection in the presence of initiator and catalyst to obtain a mixture containing ketonic acid; (2) cooling, washing, drying and distilling to obtain ketonic acid; (3) hydrogenating in the presence of Raney Ni catalyst, filtering, heating for vaporizing, dehydrating and cyclizing to obtain whiskey lactone with a yield of 87% and a refractive index ND20 of 1.441-1.447. Determined by a combination of chromatography and mass spectrometry, the whiskey lactone comprises 98% cis-isomer, as well as 2% trans-isomer. The method has such advantages as high yield, simple process, reduced wastewater discharge and is good for environmental protection.

Description

technical field [0001] The invention belongs to a preparation method of alkyl lactone compounds in fine chemical spices. Background technique [0002] Whiskey lactone (Whiskey lactone) naturally exists in whiskey and oak (Oak wood), it has a strong, long-lasting coconut and creamy aroma, mainly used in food, alcohol and tobacco flavor formulations, is a high-end precious of spices. [0003] The preparation method of the whiskey lactone of existing literature report has two kinds. Wherein, one of the methods is synthesized by nitropentane and methyl crotonate as starting materials: [0004] [0005] In this method, the raw material source is inconvenient, the reaction conditions are harsh, and the yield is not high enough. Therefore, it has no application value (Japanese Journal of Oil Chemistry, V01.32, 749 in 1983). [0006] Another preparation method is a synthesis route of using n-valeraldehyde and crotonic acid as starting materials, addition of free radicals, red...

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Problems solved by technology

[0009] The first step reaction yield of the above method is not high, the highest is only 66%; the second step reaction needs to use a large amount of expensive sodium borohydride, and using methanol as a solvent is extremely unstable, and the reaction is difficult to carry out. Excessive; the 3rd step reaction will use a large amount of dilute sulfuric acid aqueous solution, cause a large amount of waste acid water, also will extract with solution afterwards, wash and neutralize, and multiple procedures such as reclaiming solvent, cause complex process, product cost is also high (Japanese publication Charter 1988, 41473)

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