5,6-dihydropyrane and preparation method for derivative thereof

Abstract

The invention discloses a preparation method of a 5, 6-dihydrogen-pyran and the derivatives of the 5, 6-dihydrogen-pyran. In the present methods, the self-polymerization of conjugate dienes is easily happened in a synthesis reaction, and as a result, the yield rate of products is low. In the invention, under the catalysis of lewis acid, the conjugate dienes and anhydrous formaldehyde synthesize the 5, 6-dihydrogen-pyran and the derivatives by the Diels-Alder reaction; after being depolymerized by paraformaldehyde, trioxymethylene or polyoxymethylene in another reaction kettle, the anhydrous formaldehyde in the form of gas enters into the reaction kettle of synthesis reaction which is carried out under the temperature between 30 DEG C and 100 DEG C. Because the invention separates the depolymerization from the synthesis, the synthesis reaction does not have to be carried out under a high temperature, the self-polymerization of conjugate dienes is avoided, and therefore the yield rate of reaction is increased.

Description

technical field [0001] The invention relates to the field of chemistry, in particular to a preparation method of 5,6-dihydro-pyran and its derivatives. Background technique [0002] 5,6-dihydro-pyran and its derivatives are important intermediates in the organic chemical industry, which have a special fragrance and play a very important role in the perfume synthesis industry, and can also be used as a good solvents, even insecticides, fungicides, parasiticides. For example, 2-methyl-5,6-dihydro-pyran is an intermediate in the synthesis of precious spice leaf alcohol. [0003] There are many ways to synthesize 5,6-dihydro-pyran and its derivatives. The method with synthetic value is to use conjugated diolefins and aldehyde groups under Lewis (Lewis) acid catalysis, through Diels-Alder reaction (Diels-Alder), the self-polymerization of conjugated dienes at high temperatures is very serious. U.S. Patent No. 5,162,551 discloses benzaldehyde and conjugated diolefins in AlCl 3...

AI Technical Summary

Problems solved by technology

U.S. Patent No. 5,162,551 discloses benzaldehyde and conjugated diolefins in AlCl 3 2-phenyl-5,6-dihydro-2H-pyran can be synthesized under the catalysis of AlCl 3 It is also the initiator of self-polymerization of conjugated diolefins, so in the occasion where formaldehyde needs to be decomposed at high temperature, conjugated diolefins are more likely to self-polymerize, and the yield of the product is very low