Method for recovering di-trimethylolpropane and trimethylolpropane-enriched product streams from the side streams of trimethylolpropane production

Process for obtaining ditrimethylolpropane and trimethylolpropane-enriched product streams from the high-boiling fractions and residues which are obtained in the distillative purification of trimethylolpropane, characterized in that these high-boiling fractions and residues are combined and a polar solvent is added to produce a solution and the solution is treated at a temperature of 120 to 280° C. and at a pressure of 2 to 25 MPa with hydrogen in the presence of a solid nickel catalyst and an acidic compound. After catalytic treatment, the solution is subjected to multi-stage distillation including with a thin film evaporator with a column attachment in order to recover ditrimethylolpropane and trimethylolpropane-enriched product streams.