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Systematic investigations on the reactivity of oxazolinium salts
Author(s) -
Nuyken Oskar,
Maier Gerhard,
Groß Aurelia,
Fischer Herbert
Publication year - 1996
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.1996.021970106
Subject(s) - piperidine , morpholine , chemistry , counterion , nucleophile , pyridine , cationic polymerization , ring (chemistry) , polymerization , reactivity (psychology) , polymer chemistry , medicinal chemistry , organic chemistry , ion , catalysis , medicine , alternative medicine , pathology , polymer
The termination reaction of the cationic polymerization of 2‐phenyl‐ and 2‐nonyl‐2‐oxazolines was examined by reacting the corresponding model oxazolinium salts having tosylate and trifluoromethansulfonate counterions with various nucleophiles. The reaction was monitored by 1 H NMR spectroscopy. Piperidine and KOH react with the oxazolinium salts very fast and quantitatively. In the case of piperidine, the use of a double molar amount of piperidine is necessary to achieve complete conversion. The addition of piperidine, pyridine, 4‐dimethylaminopyridine and morpholine takes place in position 5 of the oxazolinium ring, whereas water and KOH add in position 2. The rate of the termination reaction depends on the electron density of the nucleophile which can be correlated with the p K a value. With CF 3 SO 3 −as counterion the addition of nucleophiles in position 5 is distinctly faster, whereas the addition of water in position 2 is much slower than with TsO − as counterion. The ring‐opening of the nonyl oxazolinium ion is slower than that of the phenyl oxazolinium ion.