PROCESS FOR PRODUCING HYDROXYL GROUP-CONTAINING ACETAL COMPOUND

PROBLEM TO BE SOLVED: To provide a process for producing an acetal compound having a hydroxyl group in the molecule in a high purity, the acetal compound being a raw material of a polyalkylene glycol derivative having an aldehyde group used for pharmaceutical preparation applications.SOLUTION: The process for producing an acetal compound represented by formula (1) (wherein n=0 or 1; when n=0, Rmay or may not be bonded to each other; Rare a 1-2C alkyl group or a 1-2C alkylene group, and may be identical or different to each other; and Ris a 1-6C alkylene group) includes, in the following order, a step (A) of dissolving an acetal compound represented by formula (1) in a solvent composed of a 5-8C hydrocarbon of ≥0.1 mass time the formula (1) to thereby obtain a solution, a step (B) of adding a buffer solution of 6 to 10 in pH of ≥0.5 mass time the formula (1) to thereby extract the acetal compound of the formula (1) in the buffer solution, a step (C) of adding one or more extracting solvents selected from the group consisting of chloroform and dichloromethane in an amount of ≥0.5 mass time the acetal compound of the formula (1) to the buffer solution in which the acetal compound has been extracted to extract the acetal compound of the formula (1) in the extracting solvents to thereby obtain an extracted solution, and a step (D) of distilling the extracted solution obtained in the step (C) under a reduced pressure of ≤0.3 kPa and at ≤65°C.