Nitrosation and denitrosation of substituted N-methylbenzenesulfonamides. Evidence of an imbalanced concerted mechanism

Abstract

The kinetics of the nitrosation reaction of several substituted sulfonamides and of the denitrosation of the resulting products have been studied. The denitrosation rate is first-order with respect to both the nitroso compound and acid concentration and no effect of added nucleophiles was observed. The denitrosation reaction is general-acid catalysed, with a Brønsted parameter, d , of 0.7, which is independent of the substituents on the aromatic ring. Kinetic solvent isotope effects range from1.20 ± 0.05 to 2.04 ± 0.06 for denitrosation by L 3 O ϩ and from k d AH /k d AD ‫؍‬ 1.5 ± 0.2 to 2.3 ± 0.3 for denitrosation by dichloroacetic acid, which suggest that a rate-determining proton transfer is involved in this reaction. For nitrosation reaction, the absence of catalysis by nucleophilic anions, the observed general-base catalysis ( NO ‫؍‬ 0.3) and the substituent effects suggest a concerted nitrosationdenitrosation process. The Leffler parameters obtained for N ؒ ؒ ؒ H bond formation ( nuc ‫؍‬ 0.7) as well as for N ؒ ؒ ؒ N᎐ ᎐ O bond breaking ( lg ‫؍‬ 0.17) are in favour of an imbalance in the transition state ( imbalance ‫؍‬ 0.53) with the development of a positive charge on the nitrogen adjacent to the nitroso group.

Stability and nitrosation efficiency of substitutedN-methyl-N-nitrosobenzenesulfonamides

“…The values of K 3 for the different sulfonamides were obtained in our laboratory. 15 For the nitrosation reaction, r(K a ) = 2.21 AE 0.04, i.e. the rate of nitrosation is more sensitive to substituent effects than the equilibrium, implying that the transition state is subject to greater stabilization by electron-withdrawing substituents than the product ion.…”

Synthesis of ruthenium(II) complexes derived from reduced imine ligands: As catalysts for transfer hydrogenation of ketones

“…2. The synthesized compounds were characterized by 1 H NMR, 13 C NMR and IR spectroscopy techniques.…”

“…The sulfonamides and their derivatives have attracted the interest of many researchers due to their importance in the development of coordination chemistry, their application in medicinal chemistry, catalytic fields, etc. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. For example, metal complexes containing sulfonamide ligands have been used as catalysts in different organic reactions [19][20][21][22][23][24][25][26].…”

Synthesis, characterization and catalytic properties of novel palladium(II) complexes containing aromatic sulfonamides: effective catalysts for the oxidation of benzyl alcohol

“…In general, sulfonamides are obtained from the reaction of sulfonyl chloride with primary or secondary amines in alkaline . Sulfonamides and their derivatives have attracted the interest of many researchers' owing to their importance in the development of coordination chemistry, and their application in medicinal chemistry, catalytic fields, etc . For example, metal complexes containing sulfonamide ligands have been used as catalysts in various organic reactions …”