Efficient heterogeneous synthesis of reactive polygalacturonic acid hydrazides

Low-methoxy ammonium pectinate (APC) and polygalacturonic acid (PG) could be transformed heterogeneously in a catalyst-free system very efficiently to the corresponding polysaccharide (PS) hydrazides. The hydrazide formation proceeds even at room temperature efficiently and is almost independent of the reaction temperature in the range from 25 of up to 80°C. In contrast to a homogeneous reaction, the heterogeneous path is efficient considering the amount of hydrazine hydrate employed. The PS hydrazides obtained show no signs of degradation or side reactions that might occur due to the basicity of the hydrazine reagent used. The polygalacturonic acid hydrazide (PGH) obtained is nontoxic as revealed by a chicken egg test. Furthermore, preliminary studies indicate that the PS hydrazides synthesized possess good metal chelating abilities, especially high amount of lead (II) can be bound from an aqueous solution.