Influence of benzene-containing reaction media on cellulose reactivity in the carboxymethylation process

The evolution of the degree of substitution during the transformation of both amorphous and crystalline domains of cellulose during carboxymethylation in systems consisting of ethanol/benzene mixtures is properly described by a pseudo-first-order kinetic equation with a higher reaction rate for less ordered regions. In the amorphous domains, the rate constants depend on the composition of the solvent mixture just for the higher molar ratio NaOH/AGU, which is the main factor influencing the reaction rate in the studied conditions. For the predominant transformation of crystalline regions, the reaction rate depends both on NaOH content and on the proportion of the two inert solvents. The increase of the reaction rate with the increase of the ratio ethanol/benzene is more pronounced than is its decrease with the increase of the molar ratio NaOH/AGU. This behavior is explained by the changes of polymorphism produced in the alkalization step.