Journal
CARBOHYDRATE RESEARCH
Volume 340, Issue 14, Pages 2229-2235Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.carres.2005.07.018
Keywords
regioselective modifications; temperature dependence; nucleophilic substitution; steric effect; tosylcellulose
Ask authors/readers for more resources
This paper investigates the nucleophilic substitution (S-N) reactions of tosylcellulose with butylamine and pyridine, respectively. The S-N reactions of tosylcellulose 1 (DSTotal 2.02; DSC-6 1.0) with butylamine carried out at 25, 50, 75 and 100 degrees 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 degrees C, substitution at C-2 also occurred at 75 and 100 degrees 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 degrees C, 40 h in butylamine. The substitution reactions of 1 with pyridine carried out at 25, 50, 75 and 100 degrees 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 degrees C. The highest regioselectivity and completeness at C-6 can be obtained at 100 degrees C for 90 h, whereas at 145 degrees C substitution also occurs at C-2. The results were proved by H-1 NMR and C-13 NMR spectroscopy. (C) 2005 Elsevier Ltd. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available