Green and Efficient: In Situ Oxidation Kinetics of
Some Tailor-Made γ‑Styrylpyridinium Dyes in Aqueous Medium Using the β‑CD-CTAP
Complex
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Abstract
β-CD-CTAP (<i>β-</i>cyclodextrin-cetyltrimethylammonium
permanganate) complex, a novel functionalized oxidant, has been used
to investigate the oxidation kinetics of some water-soluble γ-styrylpyridinium
dyes containing a trans-double bond. In absence of acid or base catalysis
and in neutral medium, the in situ oxidation process successfully
demonstrates the potential of β-CD-CTAP complex as a green oxidant,
in contrast to earlier reports on permanganate reagents. β-CD
lends a supramolecular catalysis during the reaction due to its noncovalent
interaction with CTAP. Substituent effect, reaction coefficient, deuterium
isotope effect, effect of β-CD concentration, and the values
of thermodynamic parameters help in proposing suitable mechanisms
for the oxidation process. Proportionate variation of the rate constant
values with the concentration of CTAP demonstrates the absence of
any reverse micellization phenomenon of the oxidant, in contrast to
earlier findings
