| Autor: |
Nemoto, Nobukatsu, Aizawa, Masayuki, Ueno, Yukihiko, Ikeda, Koji, Takamiya, Nobuo |
| Zdroj: |
Polymer Bulletin; 1992, Vol. 27 Issue 4, p413-420, 8p |
| Abstrakt: |
The present study describes the preparation of polyorganosiloxanes containing dialkylaminopyridines in their side chains (POS-DAAPs) and the use of them as catalysts for esterolyses of p-nitrophenyl esters of CH(CH)COOH ( n=0-5). The POS-DAAPs ( 4, 5) were prepared from poly[(3-chlorocarbonylpropyl)methylsiloxane] (PCCPMS, 1) and two pyridine derivatives, such as 4-[(2-hydroxyethyl)methylamino]pyridine (HEMAP, 2) and 4-[4-(2-hydroxyethyl)piperidino]pyridine (HEPP, 3). Pyridyl groups of POS-DAAPs 4 and 5 were partially quaternized with dimethylsulfate ( 6, 7) in order to carry out esterolysis in homogenious systems. The esterolyses were examined in methanol/tris(hydroxymethyl)-aminomethane-hydrochloric acid buffer solution (vol. ratio 2/1, pH of buffer solution: 7.5) and analyzed following Michaelis-Menten like kinetics. The second-order rate constants ( k/ K) of the esterolyses catalyzed by POSs 6 and 7 were 22-38 fold values of those catalyzed by the corresponding monomolecular catalysts 2 and 3. In addition, the effects of POSs were discussed from the kinetic, thermodynamic, and activation parameters. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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