Sodium N-chlorobenzenesulfonamide as a selective oxidant for hexosamines in alkaline medium: A kinetic and mechanistic study

Rangappa, K. S. and Raghavendra, M. P. and Mahadevappa, D. S. and Channegowda, D. (1998) Sodium N-chlorobenzenesulfonamide as a selective oxidant for hexosamines in alkaline medium: A kinetic and mechanistic study. Journal of Organic Chemistry, 63 (3). pp. 531-536.

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Official URL: https://doi.org/10.1021/jo971398t

Abstract

Oxidation of D-mannosamine (1), D-glucosamine (2), and D-galctosamine (3) by sodium N-chlorobenzenesulfonamide or chloramine-B (CAB) at 313 K is followed by a shortening of carbon chain and obeys the rate law, rate = kCAB]sugar]HO-](x), where x is less than unity. The products are arabinonic acid, ribonic acid, and erythronic acid for 1 and 2 with smaller amounts of glyceric and hexonic acids, while lyxonic and threonic acids are predominant in the oxidation of 3 with smaller amounts of glyceric and hexonic acids. Proton inventory studies made in a H2O-D2O mixture point toward a single transition state. In the proposed mechanism the alkoxy anion (S-) of the hexosamine formed in a base-catalyzed reaction at C-1 carbon is subjected to an electrophilic rate-limiting attack by Cl+ of the oxidant. The hexonic acid formed is decarboxylated with loss of ammonia to form the respective pentose, which is further converted into the corresponding pentonic acid. The breaking of the bond between C-1 and C-2 carbons in pentose yields tetronic acids. The thermodynamic parameters for sugar alkoxy anion formation and activation parameters for the rate-limiting step have been evaluated.

Item Type: Article
Subjects: C Chemical Science > Chemistry
Divisions: Department of > Chemistry
Depositing User: Users 23 not found.
Date Deposited: 07 Jun 2021 04:44
Last Modified: 04 Jul 2022 07:09
URI: http://eprints.uni-mysore.ac.in/id/eprint/16729

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