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Dialkylaminopyridine catalysed esterolysis of p-nitrophenyl alkanoates in different cationic microemulsions

Bhattacharya, Santanu and Snehalatha, Karnam (1996) Dialkylaminopyridine catalysed esterolysis of p-nitrophenyl alkanoates in different cationic microemulsions. In: Perkin Transactions 2 (9). 2021-2025 .

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The reactions of p-nitrophenyl alkanoate esters with dialkylaminopyridine (DAAP) and its related mono- and di-anionic water-soluble derivatives have been studied separately in three different microemulsion (ME) media. These were (a) oil-in-water ME (O/W), (b) water-in-oil ME (W/O) and (c) a bicontinuous ME, where oil and water are in nearly comparable amounts. All the ME systems were stabilized by cationic surfactant, cetyltrimethylammonium bromide (CTABr) and butanol as a cosurfactant. The second-order rate constants (k(2)) in the microemulsion media were also determined : over a phase volume (phi) of approximately 0.13-0.46. In order to explain the contribution of effective concentration of the nucleophiles in the aqueous pseudophase, corrected rate constants k(2 phi) = k(2)(1 - phi) were obtained, The rate constants of the corresponding hydrolytic reactions were also examined in CTABr micelles. While the DAAP catalysts were partitioned between the micellar and aqueous pseudophases in ME, the hydrophobic substrates were found to be mainly confined to oil-rich phases, Present results indicate that the main effect of ME media on the hydrolysis reaction is due,to both electrostatic reasons and substrate partitioning.

Item Type: Journal Article
Publication: Perkin Transactions 2
Publisher: Royal Society of Chemistry
Additional Information: Copyright of this article belongs to Royal Society of Chemistry.
Department/Centre: Division of Chemical Sciences > Organic Chemistry
Date Deposited: 07 May 2011 05:26
Last Modified: 07 May 2011 05:26
URI: http://eprints.iisc.ac.in/id/eprint/37111

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