High-resolution nuclear magnetic resonance spectroscopy studies of polysaccharides crosslinked by sodium trimetaphosphate: a proposal for the reaction mechanism

Abstract : An NMR spectroscopy study (31P, 1H, 13C) of the postulated crosslinking mechanism of sodium trimetaphosphate (STMP) on polysaccharides is reported using methyl α-d-glucopyranoside as a model. In a first step, reaction of STMP with Glc-OMe gives grafted sodium tripolyphosphate (STPPg). On the one hand, STTPg can react with a second alcohol functionality to give a crosslinked monophosphate. On the other hand, a monophosphate (grafted phosphate) could be obtained by alkaline degradation of STPPg. NMR spectroscopy allows to detect the various species formed and to obtain the crosslinking density of STMP–polysaccharides hydrogels.