Process for the preparaton of low molecular weight polyhydroxyl compounds

In a process for the preparation of low molecular weight polyhydroxyl compounds wherein formaldehyde hydrate is condensed in the presence of soluble or insoluble compounds of metals of the 2nd to 4th Main Group or 2nd to 8th sub-Group of the Periodic System of Elements as catalyst, and optionally in the presence of compounds capable of enediol formation as cocatalyst and/or of low molecular weight and/or higher molecular weight polyhydroxyl compounds, the improvement which comprises controlling the pH during the condensation reaction by the addition of from 5 to 200 milliequivalents, based on 1 mol of formaldehyde, of N-methylmorpholine, N,N'-dimethylpiperazine or addition products, with a molecular weight of up to 1,000, of ethylene oxide and/or propylene oxide with morpholine or piperazine.