Kinetics of oxidation of acidic amino acids and their monoamides by N‐chloroarylsulphonamides in aqueous acidic medium

Abstract

Twelve sodium salts of N‐chloroarylsulphonamides were employed as oxidants for studying the kinetics of oxidation of two acidic amino acids (aspartic and glutamic acid) and their monoamides (aspargine and glutamine) in aqueous acidic medium under various conditions, to see how the oxidative strength of these reagents vary with substitution. The sodium salts of N‐chloroarylsulphonamides employed are of the general formulae i‐X‐C6H4SO2NaNCl·xH2O (where i‐X = 4‐C2H5, 4‐F, 4‐Cl or 4‐Br) and i‐X‐j‐Y‐C6H3SO2NaNCl·xH2O [where i‐X‐j‐Y = 2,3‐(CH3)2, 2,4‐(CH3)2, 2,5‐(CH3)2, 2‐CH3‐4‐Cl, 2,4‐Cl2 and 3,4‐Cl2]. The reactions show second‐order kinetics in [oxidant], fractional order in [amino acid] and an inverse dependence on [H+]. Addition of the reduced product of the oxidants or variation in ionic strength of the medium has no significant effect on the rates of oxidations. Mechanisms in conformity with the observed kinetics are discussed. The effective oxidizing species of the oxidants is Cl+ in different forms. The oxidizing strengths of N‐chloroarylsulphonamides depend on the ease with which Cl+ is released from them. The study reveals that the introduction of electron‐withdrawing groups such as halides to the benzene ring eases the release of Cl+ from the reagent and hence increases the oxidizing strengths of the N‐chloroarylsulphonamides. The effect of substituents on Ea of the reactions was analysed by optimising Ea with reference to log A, and log A with reference to Ea of the parent oxidant. Copyright © 2004 John Wiley & Sons, Ltd.

PotassiumN,2-dichlorobenzenesulfonamidate sesquihydrate

“…For our studies of the effect of substituents on the structures of N-haloarylsulfonamides, see: Gowda et al (2010Gowda et al ( , 2011a; and on the oxidative strengths of N-haloarylsulfonamides, see: Gowda & Shetty (2004); Usha & Gowda (2006). For similar structures, see: George et al (2000); Olmstead & Power (1986).…”

Kinetic study of the formation of N‐chloro compounds using N‐chlorosuccinimide

“…N ‐Chloro compounds are reagents that are frequently used in the intermediate steps of the synthesis of organic compounds . Sodium hypochlorite, N ‐chlorosuccinimide (NCS), chloramine‐T, chloramine‐B, and tert‐butyl hypochlorite are some of the most common reagents used to obtain N ‐chloro compounds . All of them contain one electrophile chlorine atom, positive chlorine, able to react with amino acids, amines, amides, and other nitrogenous compounds to form the corresponding N ‐chloro compound.…”

“…[1][2][3][4][5][6][7] Sodium hypochlorite, N-chlorosuccinimide (NCS), chloramine-T, chloramine-B, and tert-butyl hypochlorite are some of the most common reagents used to obtain N-chloro compounds. [8][9][10][11][12][13][14][15] All of them contain one electrophile chlorine atom, positive chlorine, able to react with amino acids, amines, amides, and other nitrogenous compounds to form the corresponding N-chloro compound. These reactions occur by the rupture of the N-H bond and formation of the N-Cl bond.…”

Use of N-chloro-N-methyl-p-toluenesulfonamide in N-chlorination reactions

“…The most commonly used reagents for the preparation of N‐chloro compounds are among others: sodium hypochlorite, N‐chlorosuccinimide, Chloramine‐T (CAT), Chloramine‐B (CAB) and tert‐butylhypochlorite ( t BuOCl) . All of them contain a chlorine atom electrophile, positive chlorine, able to react with the amino groups (R 1 R 2 NH) of amino acids, amines, amides and other nitrogenous compounds, to form the corresponding N‐chloro compounds, in a reaction in that takes place the process of breaking a NH bond and formation of the NCl bond.…”