Preparation of high functional cellulose derivatives by active esterification and aminolysis

点击翻译按钮获取中文摘要

The aminolyses of alkyl acetates carrying electron-withdrawing substituents in leaving groups were investigated. The relative rates in DMF were found to be as follows : 1 for ethyl acetate, 37 for beta-chloroethyl acetate, 87 for beta-cyanoethyl acetate, and 2700 for trichloroethyl acetate. These reactions followed the Taft equation, and it was concluded that the inductive effect plays an important role in the activation of these alkyl acetates.Carboxymethyl cellulose was esterificated with alcohols having electron-withdrawing groups, using DCC as the dehydrating sgent. The aminolyses of these actively esterificated celluloses took place easily, but yields were low, e.g.25% because of the formation of lactone ring between C_2-carboxyl and C_3-hydroxyl groups during the esterification.To prevent this phenomenum, carboxymethylation of methyl cellulose (MC) in which C_2 or C_3-hydroxyl groups were blocked was carried out. The problem of lactone formation was solved. Unfortunately, however, considerable amount of active ester groups were hydrolyzed during purification by the dialysis. Thus it is needed that the samples are used without purification or proper precipitating agent is seeked.Vinyl monomers bearing active ester group such as N-acryloxy succinimide were prepared and grafted onto cellulose using cerium (IV) salt. Grafting was confirmed by an increase in weight and IR spectra. Amylase was immobilized onto the grafted celluloses in the phosphoric acid buffer (pH6.3) solution at 37ﾟC.The activity of immobilized enzyme was about 10% of that of original amylase, but the activity was little lowered even after repeated usage 10 times. It was speculated that the low activity of immobilized enzyme depends on the reaction of active parts of enzyme because of high density of active ester groups. To prepare the carrier resolving optical isomers, celluloses with active ester groups and also isocyanate groups were allowed to react with (R) -2-amino-1-butanol.