A time-resolved kinetic study of the hydrogen atom abstraction reactions from phenol by the cumyloxyl radical (CumO•) was carried out in different solvents. The hydrogen atom abstraction rate constant (kH) was observed to decrease by almost 3 orders of magnitude on going from isooctane to MeOH. In TFE, MeCN/H2O 2:1, and MeOH, the measured kH values were lower than expected on the basis of the Snelgrove−Ingold (SI) equation that correlates log kH to the solvent hydrogen bond acceptor (HBA) ability parameter β2 H. As these solvents also act as hydrogen bond donors (HBDs), we explored the notion that a more thorough description of solvent effects could be provided by including a solvent HBD ability term, α2 H, into the SI equation via β2 H(1 + α2 H). The inclusion of such a term greatly improves the fitting for TFE, MeCN/H2O 2:1, and MeOH but at the expense of that for tertiary alkanols. This finding suggests that, for the reaction of CumO• with phenol, the HBA and HBD abilities of both the solvent and the substrate could be responsible for the observed KSEs. but this requires that primary and tertiary alkanols exhibit different solvation behaviors. Possible explanations for this different behavior are explored.

Bietti, M., Salamone, M., Dilabio, G., Jockusch, S., Turro, N. (2012). Kinetic Solvent Effects on Hydrogen Abstraction from Phenol by the Cumyloxyl Radical. Towards an Understanding of the Role of Protic Solvents. JOURNAL OF ORGANIC CHEMISTRY, 77, 1267-1272 [10.1021/jo201454c].

Kinetic Solvent Effects on Hydrogen Abstraction from Phenol by the Cumyloxyl Radical. Towards an Understanding of the Role of Protic Solvents

BIETTI, MASSIMO;SALAMONE, MICHELA;
2012-01-04

Abstract

A time-resolved kinetic study of the hydrogen atom abstraction reactions from phenol by the cumyloxyl radical (CumO•) was carried out in different solvents. The hydrogen atom abstraction rate constant (kH) was observed to decrease by almost 3 orders of magnitude on going from isooctane to MeOH. In TFE, MeCN/H2O 2:1, and MeOH, the measured kH values were lower than expected on the basis of the Snelgrove−Ingold (SI) equation that correlates log kH to the solvent hydrogen bond acceptor (HBA) ability parameter β2 H. As these solvents also act as hydrogen bond donors (HBDs), we explored the notion that a more thorough description of solvent effects could be provided by including a solvent HBD ability term, α2 H, into the SI equation via β2 H(1 + α2 H). The inclusion of such a term greatly improves the fitting for TFE, MeCN/H2O 2:1, and MeOH but at the expense of that for tertiary alkanols. This finding suggests that, for the reaction of CumO• with phenol, the HBA and HBD abilities of both the solvent and the substrate could be responsible for the observed KSEs. but this requires that primary and tertiary alkanols exhibit different solvation behaviors. Possible explanations for this different behavior are explored.
4-gen-2012
Pubblicato
Rilevanza internazionale
Articolo
Esperti anonimi
Settore CHIM/06 - CHIMICA ORGANICA
English
Con Impact Factor ISI
Bietti, M., Salamone, M., Dilabio, G., Jockusch, S., Turro, N. (2012). Kinetic Solvent Effects on Hydrogen Abstraction from Phenol by the Cumyloxyl Radical. Towards an Understanding of the Role of Protic Solvents. JOURNAL OF ORGANIC CHEMISTRY, 77, 1267-1272 [10.1021/jo201454c].
Bietti, M; Salamone, M; Dilabio, G; Jockusch, S; Turro, N
Articolo su rivista
File in questo prodotto:
File Dimensione Formato  
joc2012-1.pdf

solo utenti autorizzati

Licenza: Copyright dell'editore
Dimensione 308.16 kB
Formato Adobe PDF
308.16 kB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/76317
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 19
  • ???jsp.display-item.citation.isi??? 20
social impact