Catalyses by polymer complexes. Part 3. Polymer micellar catalysis of isoalloxazine (flavin) oxidation of thiols

Seiji Shinkai, Reiko Ando, Toyoki Kunitake

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Abstract

The effect of cationic polymer micelles on the isoalloxazine (flavin) oxidation of thiols is reported: the polymers employed were poly-(2-ethyl-1-vinylimidazole) quaternized with ethyl bromide and lauryl bromide [lauryl group content: 8.8 mol % (L-9), 28.9 mol % (L-29), and 40.9 mol % (L-41)]. Addition of L-29 and L-41 polymers caused a red shift of the u.v. absorption maximum of thiophenoxide ion and an increase in its acid dissociation constant, while L-9 polymer scarcely affected these values. Under anaerobic conditions, the oxidation of thiophenol and 2-mercaptoethanol by 10-ethyl-3-methylisoalloxazine in the presence of micelle-like polymers (L-29 and L-41) was 102-105 times faster than the corresponding reaction in a non-polymeric system, whereas L-9, a polyelectrolyte-like polymer, produced almost no acceleration. The thiolate anion bound to the polymer domain is activated probably due to the formation of a hydrophobic ion pair. On the other hand, the oxidation of butane-1,4-dithiol was not much affected by the polymer micelle. The difference in mechanism of dithiol oxidation is discussed in connection with the microenvironmental effect.

Original languageEnglish
Pages (from-to)1271-1277
Number of pages7
JournalJournal of the Chemical Society, Perkin Transactions 2
Issue number12
Publication statusPublished - Dec 1 1978

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Sulfhydryl Compounds
Catalysis
Polymers
Oxidation
Micelles
Bromides
Ions
4,6-dinitro-o-cresol
isoalloxazine
Mercaptoethanol
Polyelectrolytes
Anions
Acids

All Science Journal Classification (ASJC) codes

  • Chemistry(all)

Cite this

Catalyses by polymer complexes. Part 3. Polymer micellar catalysis of isoalloxazine (flavin) oxidation of thiols. / Shinkai, Seiji; Ando, Reiko; Kunitake, Toyoki.

In: Journal of the Chemical Society, Perkin Transactions 2, No. 12, 01.12.1978, p. 1271-1277.

Research output: Contribution to journalArticle

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AB - The effect of cationic polymer micelles on the isoalloxazine (flavin) oxidation of thiols is reported: the polymers employed were poly-(2-ethyl-1-vinylimidazole) quaternized with ethyl bromide and lauryl bromide [lauryl group content: 8.8 mol % (L-9), 28.9 mol % (L-29), and 40.9 mol % (L-41)]. Addition of L-29 and L-41 polymers caused a red shift of the u.v. absorption maximum of thiophenoxide ion and an increase in its acid dissociation constant, while L-9 polymer scarcely affected these values. Under anaerobic conditions, the oxidation of thiophenol and 2-mercaptoethanol by 10-ethyl-3-methylisoalloxazine in the presence of micelle-like polymers (L-29 and L-41) was 102-105 times faster than the corresponding reaction in a non-polymeric system, whereas L-9, a polyelectrolyte-like polymer, produced almost no acceleration. The thiolate anion bound to the polymer domain is activated probably due to the formation of a hydrophobic ion pair. On the other hand, the oxidation of butane-1,4-dithiol was not much affected by the polymer micelle. The difference in mechanism of dithiol oxidation is discussed in connection with the microenvironmental effect.

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