PubMed:16099440 JSONTXT

{"project":"sentences","denotations":[{"id":"TextSentencer_T1","span":{"begin":0,"end":139},"obj":"Sentence"},{"id":"TextSentencer_T2","span":{"begin":140,"end":272},"obj":"Sentence"},{"id":"TextSentencer_T3","span":{"begin":273,"end":684},"obj":"Sentence"},{"id":"TextSentencer_T4","span":{"begin":685,"end":772},"obj":"Sentence"},{"id":"TextSentencer_T5","span":{"begin":773,"end":910},"obj":"Sentence"},{"id":"TextSentencer_T6","span":{"begin":911,"end":1031},"obj":"Sentence"},{"id":"TextSentencer_T7","span":{"begin":1032,"end":1229},"obj":"Sentence"},{"id":"TextSentencer_T8","span":{"begin":1230,"end":1383},"obj":"Sentence"},{"id":"TextSentencer_T9","span":{"begin":1384,"end":1443},"obj":"Sentence"},{"id":"T1","span":{"begin":0,"end":139},"obj":"Sentence"},{"id":"T2","span":{"begin":140,"end":272},"obj":"Sentence"},{"id":"T3","span":{"begin":273,"end":684},"obj":"Sentence"},{"id":"T4","span":{"begin":685,"end":772},"obj":"Sentence"},{"id":"T5","span":{"begin":773,"end":910},"obj":"Sentence"},{"id":"T6","span":{"begin":911,"end":1031},"obj":"Sentence"},{"id":"T7","span":{"begin":1032,"end":1229},"obj":"Sentence"},{"id":"T8","span":{"begin":1230,"end":1383},"obj":"Sentence"},{"id":"T9","span":{"begin":1384,"end":1443},"obj":"Sentence"}],"namespaces":[{"prefix":"_base","uri":"http://pubannotation.org/ontology/tao.owl#"}],"text":"New 6-butylamino-6-deoxycellulose and 6-deoxy-6-pyridiniumcellulose derivatives with highest regioselectivity and completeness of reaction.\nThis 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."}