Oxidation of substituted benzyl alcohols by quinoxalinium dichromate. A kinetic study

Ozgun B., Degirmenbasi N.

MONATSHEFTE FUR CHEMIE, cilt.135, sa.5, ss.483-491, 2004 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 135 Sayı: 5
  • Basım Tarihi: 2004
  • Doi Numarası: 10.1007/s00706-003-0143-9
  • Dergi Adı: MONATSHEFTE FUR CHEMIE
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.483-491
  • Anahtar Kelimeler: quinoxalinium dichromate, oxidation, kinetics, mechanism, QUINOLINIUM CHLOROCHROMATE, EFFICIENT REAGENT, ORGANIC-COMPOUNDS, MECHANISM, FLUOROCHROMATE, BROMOCHROMATE, CHROMIUM(VI), BROMINATION
  • Gazi Üniversitesi Adresli: Evet

Özet

Quinoxalinium dichromate (QxDC) oxidizes benzyl alcohol and substituted benzyl alcohols smoothly in dimethyl sulfoxide (DMSO) and in the presence of acid to the corresponding aldehydes. The reaction has unit dependence on each of the alcohol, QxDC, and acid concentrations. Electron-releasing substituents accelerate the reaction, whereas electron-withdrawing groups retard the reaction, and the rate data obey Hammett's relationship. The reaction constant rho was -1.09 +/- 0.01 at 303 K. Oxidation of alpha,alpha-dideuteriobenzyl alcohol indicated the presence of a substantial primary kinetic isotope effect (k(H)/k(D) = 6.78 at 303 K). The reaction failed to induce the polymerization of acrylonitrile. The rates of oxidation were determined at different temperatures and the activation parameters were evaluated. The analysis of the dependence of the kinetic isotope effect on temperature indicated that the reaction involves a symmetrical cyclic transition state. A suitable mechanism is proposed.