The model reaction between the (R)-1,3-dimethyl-1-cyclohexyl cation (I) and methanol has been investigated under gas-phase radiolytic conditions (750 Torr; 25–120 °C) with the aim of evaluating the intrinsic factors that govern the facial selectivity of biased carbocations. The peculiarity of the experimental approach allows the formation of different CH318OH⋅I ionic adducts. Subsequent conversion of these adducts to give the corresponding E/Z covalent products follows different reaction coordinates, which are characterized by their own activation parameters. On the grounds of density functional theory (DFT) results, several [CH3OH⋅I] structures have been located on the relevant potential-energy surface (PES). The experimental results point to a gas-phase facial selectivity, which is mainly governed by entropic factors that arise as a result of the occurrence of different noncovalent ion–molecule “facial adducts” (FA). The formation of FAs may also play an important role in both the reaction dynamics and the positional selectivity. The present results cannot be interpreted by any of the models based on solution-phase experiments.

Facial selectivity of the (R)-1,3.dimethyl-1-cyclohexyl cation in the gas phase / Filippi, Antonello. - In: CHEMISTRY-A EUROPEAN JOURNAL. - ISSN 0947-6539. - STAMPA. - 9:(2003), pp. 5396-5403. [10.1002/chem.200304859]

Facial selectivity of the (R)-1,3.dimethyl-1-cyclohexyl cation in the gas phase.

FILIPPI, Antonello
2003

Abstract

The model reaction between the (R)-1,3-dimethyl-1-cyclohexyl cation (I) and methanol has been investigated under gas-phase radiolytic conditions (750 Torr; 25–120 °C) with the aim of evaluating the intrinsic factors that govern the facial selectivity of biased carbocations. The peculiarity of the experimental approach allows the formation of different CH318OH⋅I ionic adducts. Subsequent conversion of these adducts to give the corresponding E/Z covalent products follows different reaction coordinates, which are characterized by their own activation parameters. On the grounds of density functional theory (DFT) results, several [CH3OH⋅I] structures have been located on the relevant potential-energy surface (PES). The experimental results point to a gas-phase facial selectivity, which is mainly governed by entropic factors that arise as a result of the occurrence of different noncovalent ion–molecule “facial adducts” (FA). The formation of FAs may also play an important role in both the reaction dynamics and the positional selectivity. The present results cannot be interpreted by any of the models based on solution-phase experiments.
2003
01 Pubblicazione su rivista::01a Articolo in rivista
Facial selectivity of the (R)-1,3.dimethyl-1-cyclohexyl cation in the gas phase / Filippi, Antonello. - In: CHEMISTRY-A EUROPEAN JOURNAL. - ISSN 0947-6539. - STAMPA. - 9:(2003), pp. 5396-5403. [10.1002/chem.200304859]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/49207
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