New 6-butylamino-6-deoxycellulose and 6-deoxy-6-pyridiniumcellulose derivatives with highest regioselectivity and completeness of reaction Original Research Article

This paper investigates the nucleophilic substitution (SN) reactions of tosylcellulose with butylamine and pyridine, respectively. The SN reactions of tosylcellulose 1 (DSTotal 2.02; DSC-6 1.0) with butylamine carried out at 25, 50, 75 and 100 °C in both dimethyl sulfoxide (DMSO) and pure butylamine showed that the regioselectivity of substitution at C-6 of cellulose is temperature dependent: the highest regioselectivity at C-6 can be reached at 25 and 50 °C; substitution at C-2 also occurred at 75 and 100 °C. The substitution speed in pure butylamine is greater than that in the presence of DMSO. A complete and regioselective substitution at C-6 with a DS of 1.0 was obtained under the conditions of 50 °C, 40 h in butylamine. The substitution reactions of 1 with pyridine carried out at 25, 50, 75 and 100 °C for 24 h in DMSO did not occur. In contrast to this the SN reactions done in pure pyridine showed that a temperature- and steric-dependent, regioselective substitution took place at C-6 at temperatures from 25 to 145 °C. The highest regioselectivity and completeness at C-6 can be obtained at 100 °C for 90 h, whereas at 145 °C substitution also occurs at C-2. The results were proved by 1H NMR and 13C NMR spectroscopy.