METHOD FOR PRODUCING TETRAHYDRO-4H-PYRAN-4-ONE

PURPOSE: To obtain tetrahydro-4H-pyran-4-one useful as a synthetic raw material for fine chemicals such as a medicine, capable of reducing the generation of an insoluble material by reacting a 1,5-dihalopentan-3-one in the presence of a specific catalyst and water. CONSTITUTION: The method for producing tetrahydro-4H-pyran-4-one comprises reacting a compound of formula I (X is a halogen) in the presence of a phosphoric acid salt (e.g. sodium dihydrogenphosphate), a halogenated alkali or alkaline earth metal (e.g. sodium chloride) and water, and if necessary in the copresence of a carboxylic acid or salt thereof (e.g. salicylic acid) at 90-105 deg.C for 0.5-6hr to obtain the compound of formula II. The phosphoric acid salt of 4-1.8 fold mole in the case of dihydrogen salt based on the compound of the formula I, 0.01-0.5g halogenated alkali or alkaline earth metal per 1ml water and 1-20ml water based on 1g compound of the formula I are used. This production method can reduce the generation of an insoluble material sticking to the wall of a vessel and hardly removable since it is insoluble to various organic solvents, and simplify the post treatments of the reaction.