ISSN:
0894-3230
Keywords:
Organic Chemistry
;
Physical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The reaction between α-tocopheroxyl radical (VE·) and ascorbic acid (VC) and its lipophilic derivatives ascorbyl-6-caprylate (VC-8), 6-laurate (VC-12) and 6-palmitate (VC-16) was studied by stopped-flow ESR spectroscopy in cetyltrimethylammonium bromide (CTAB) micelles. The second-order rate constants for the reaction were found to be 9 · 0, 3 · 0, 0 · 7 and 0 · 03 × 105 1 mol-1 s-1 for VC, VC-8, VC-12 and VC-16, respectively, indicating a remarkable influence of the aliphatic side-chain on the reactivity. The lifetime of the reaction intermediate, ascorbate radical anion, was greatly enhanced by the lipophilic side-chain, being 0 · 4, 5 and 110 s for VC-8-., VC-12-. and VC-16-. respectively. Kinetic analysis shows that the inter- and intramicellar diffusion may be the rate-limiting steps for the reaction carried out in micelles.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/poc.610050105
