Method for producing diol having cyclic acetal skeleton

A method for producing a diol having a cyclic acetal skeleton, the method comprising:

• conducting a first acetalization reaction of a raw material hydroxypivalaldehyde and at least pentaerythritol and/or trimethylolpropane under an acid catalyst, to obtain a reaction solution comprising the diol having the cyclic acetal skeleton;
• separating the diol having the cyclic acetal skeleton, which is precipitated in the reaction solution, to obtain a reaction mother liquor;
• and
• conducting a second acetalization reaction of a rain material hydroxypivalaldehyde and at least pentaerythritol and/or trimethylolpropane under the reaction mother liquor and an acid catalyst, to obtain the diol having the cyclic acetal skeleton,
• wherein the separating and the second acetalization reaction are conducted more than once,
• wherein the raw material hydroxypivalaldehyde comprises an impurity selected from the group consisting of formaldehyde, neopentyl glycol, isobutyraldehyde and an ester compound having a neopentyl glycol skeleton of formula (III):
• wherein R represents a hydrocarbon group having 1 to 4 carbon atoms, a hydrocarbon group having a hydroxy group and having 1 to 4 carbon atoms, or a hydrogen atom, and
• wherein when the impurity comprises the formaldehyde, a content of the formaldehyde is 0.80% by mass or less;
• when the impurity comprises the neopentyl glycol and/or the ester compound, a total molar concentration of the neopentyl glycol and/or the ester compound is 0.100 mol/kg or less;
• and
• when the impurity comprises the isobutyraldehyde, a content of the isobutyraldehyde is 0.05% by mass or less,
• all based on 100% by mass of the raw material hydroxypivalaldehyde.