The gas-phase acidity of ionized benzyl alcohol and of some of its derivatives with selected reference bases has been studied by Fourier Transform Ion Cyclotron Resonance (FT-ICR) mass spectrometry. The aim was to relate the gas-phase reactivity to the behavior in aqueous solution of the radical cations of benzyl alcohols bearing methoxy substituent(s) on the phenyl ring which are known to undergo deprotonation at both the CH2 and OH groups. The dual reactivity behavior is confirmed in the gas phase, in which the prototypical ion, C6H5CH2OH.+, is deprotonated at both the CH2 and OH groups, whereas the ring hydrogens are not involved. An increasing extent of O-deprotonation is shown as the strength of the base increases. Appropriate methyl substitution, as in the radical cations of C6H5C(Me)2OH and C6H5CH2OMe, allows only O- or C-acidity. The two processes are characterized by comparable thermodynamic features with a Gas-phase Basicity (GB) value of 852 kJ mol−1 for the cumyloxyl radical and 850 kJ mol−1 for the α-methoxybenzyl radical. The possible origin of the observed mechanistic dichotomy is discussed.

THE DEPROTONATION OF BENZYL ALCOHOL RADICAL CATIONS : A MECHANISTIC DICHOTOMY IN THE GAS PHASE AS IN SOLUTION / Baciocchi, Enrico; M., Bietti; Chiavarino, Barbara; Crestoni, Maria Elisa; Fornarini, Simonetta. - In: CHEMISTRY-A EUROPEAN JOURNAL. - ISSN 0947-6539. - STAMPA. - 8:(2002), pp. 532-537. [10.1002/1521-3765(20020118)8:2<532::AID-CHEM532>3.0.CO;2-T]

THE DEPROTONATION OF BENZYL ALCOHOL RADICAL CATIONS : A MECHANISTIC DICHOTOMY IN THE GAS PHASE AS IN SOLUTION

BACIOCCHI, Enrico;CHIAVARINO, Barbara;CRESTONI, Maria Elisa;FORNARINI, Simonetta
2002

Abstract

The gas-phase acidity of ionized benzyl alcohol and of some of its derivatives with selected reference bases has been studied by Fourier Transform Ion Cyclotron Resonance (FT-ICR) mass spectrometry. The aim was to relate the gas-phase reactivity to the behavior in aqueous solution of the radical cations of benzyl alcohols bearing methoxy substituent(s) on the phenyl ring which are known to undergo deprotonation at both the CH2 and OH groups. The dual reactivity behavior is confirmed in the gas phase, in which the prototypical ion, C6H5CH2OH.+, is deprotonated at both the CH2 and OH groups, whereas the ring hydrogens are not involved. An increasing extent of O-deprotonation is shown as the strength of the base increases. Appropriate methyl substitution, as in the radical cations of C6H5C(Me)2OH and C6H5CH2OMe, allows only O- or C-acidity. The two processes are characterized by comparable thermodynamic features with a Gas-phase Basicity (GB) value of 852 kJ mol−1 for the cumyloxyl radical and 850 kJ mol−1 for the α-methoxybenzyl radical. The possible origin of the observed mechanistic dichotomy is discussed.
Proton transfer reactions; FT-ICR mass spectrometry; Reaction mechanism; Gas phase ion chemistry
01 Pubblicazione su rivista::01a Articolo in rivista
THE DEPROTONATION OF BENZYL ALCOHOL RADICAL CATIONS : A MECHANISTIC DICHOTOMY IN THE GAS PHASE AS IN SOLUTION / Baciocchi, Enrico; M., Bietti; Chiavarino, Barbara; Crestoni, Maria Elisa; Fornarini, Simonetta. - In: CHEMISTRY-A EUROPEAN JOURNAL. - ISSN 0947-6539. - STAMPA. - 8:(2002), pp. 532-537. [10.1002/1521-3765(20020118)8:2<532::AID-CHEM532>3.0.CO;2-T]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/249877
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