Verbessertes Oxidationsverfahren zur Herstellung von Polycarboxylaten aus Polysacchariden

摘要

A process for producing polycarboxylic acids or their salts from polysaccharides by oxidation with gaseous nitrogen dioxide/dinitrogen tetroxide with the conversion of at least a part of the primary alcohol groups of the polysaccharides into carboxyl groups and possibly the at least partial neutralisation of the carboxylic acid groups produced is to be optimised. This has essentially been achieved in that nitrogen dioxide/dinitrogen tetroxide is taken at a charging temperature in the region of the boiling point of nitrogen dioxide at the prevailing pressure to a temperature 50 DEG C thereabove, which is at least partially absorbed by the polysaccharide, and then primary alcohol groups are oxidised to carboxyl groups at a temperature at least 10 DEG C above the charging temperature.