Evaluation of molten inorganic salt hydrates as reaction medium for the derivatization of cellulose

Molten inorganic salt hydrates are highly efficient solvents for cellulose. The carboxymethylation of the polymer dissolved in this new group of cellulose solvents was investigated. The homogeneous carboxymethylation of cellulose in molten LiClO4.3H(2)O using sodium monochloroacetate in the presence of NaOH is possible. The formation of CMC was confirmed by FT- Raman spectroscopy. Structure analysis by means of HPLC after chain degradation showed the formation of CMC with a DS of 2 after a short reaction time of 4 h. The derivatives exhibit a statistical distribution of substituents along the polymer chain if prepared in molten LiClO4.3H(2)O as solvent. A substituent distribution in the order C- 6 > C- 2 approximate to C- 3 for anhydroglucose units (AGU) was concluded from H-1- NMR measurements. The synthesis of CMC in the swelling medium LiCl.xH(2)O (2 less than or equal to x less than or equal to 5) yields polymers with a statistical distribution of functional groups along the chain. The water content of the salt melts has a dramatic influence on the DSCMC.