ISSN:
0887-624X
Schlagwort(e):
poly(4-vinyl-2-hydroxypyridine
;
2,3,4,6-tetramethyl-α-D-glucose
;
mutarotation
;
catalytic activity
;
complex formation
;
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
Poly(4-vinyl-2-hydroxypyridine), PVHP, was prepared by the reaction of poly(4-vinylpyridine) with hydrogen peroxide in acetic acid, and subsequent refluxing in acetic anhydride at 150°C. Conversion of pyridine units to 2-hydroxypyridine units was about 75% and the obtained product was a deep-brown powder. Mutarotation rates of 2,3,4,6-tetramethyl-α-D-glucose, TMG, in chloroform and in ethanol in the presence of the PVHP were measured and compared with those in the presence of 2-hydroxypyridine. The PVHP was found to show higher catalytic activities on the mutarotation than 2-hydroxypyridine in both solvents, which was deduced to be due to more efficient formation of the complex between TMG and the catalyst molecules. The mutarotation rates were higher in chloroform than in ethanol for both catalysts, which suggests that the mutarotation in the presence of the catalyst is more favorable in the strongly hydrogen bonding solvent because of higher interaction between the substrate and the catalyst molecules. The mutarotation rates increased proportionally with increasing concentration of the substrate in both solvents and in the presence of both catalyst, while they increased but not proportionally with increasing concentration of the catalyst; the increase began to level-off with increasing concentration of the catalyst. The latter tendency was assumed to result from the association of the catalyst units themselves, which makes efficiency of the complex formation between TMG and the catalyst molecules lower. © 1993 John Wiley & Sons, Inc.
Zusätzliches Material:
7 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/pola.1993.080310123
