Patent ID: 7301058

Claim:
A process for preparing polyhydric alcohols in increased yields comprising aldolizing formaldehyde with a higher aldehyde in the presence of catalytic amounts of a tertiary amine and hydrogenating the resulting mono- or polymethylolalkanals, said process further comprising the steps of: a) distillative removal of components having lower boiling points than the polyhydric alcohol from the crude product of the hydrogenation of the mono- or polymethylolalkanals; b) separation of the resulting bottom product in a second distillation stage into a high boiler fraction and a fraction comprising the majority of the polyhydric alcohol; c) acid treatment of the high boiler fraction, the water content of the high boiler fraction being from 20% to 90% by weight, based on the total amount of high boiler fraction and water; and d) distillation of the fraction comprising the majority of the polyhydric alcohol to remove the more volatile compounds (medium boiler fraction) and recovery of pure polyhydric alcohol; wherein the acid-treated high boiler fraction is recycled into the hydrogenation of the mono- or polymethylolalkanals to the polyhydric alcohol.