New 6-butylamino-6-deoxycellulose and 6-deoxy-6-pyridiniumcellulose derivatives with highest regioselectivity and completeness of reaction.
This paper investigates the nucleophilic substitution (S(N)) reactions of tosylcellulose with butylamine and pyridine, respectively. The S(N) reactions of tosylcellulose 1 (DS(Total) 2.02; DS(C-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 24h in DMSO did not occur. In contrast to this the S(N) 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 1H NMR and 13C NMR spectroscopy.
Liu
Chun
C
ITMC, Institute of Technical Chemistry and Macromolecular Chemistry, Hemocompatible and Biocompatible Biomaterials, University of Technology Aachen, Worringer Weg 1, D-52074 Aachen, Germany. chunliu70@yahoo.com
Baumann
Hanno
H
D002082:Butylamines / Q000737:chemistry; D002482:Cellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D004121:Dimethyl Sulfoxide; D011725:Pyridines / Q000737:chemistry; D011726:Pyridinium Compounds / Q000737:chemistry*; D013816:Thermodynamics
D002082:Butylamines; D011725:Pyridines; D011726:Pyridinium Compounds; D002482:Cellulose; C023666:pyridine; D004121:Dimethyl Sulfoxide