O-protonated 1-aryl-l-methoxyethanes

Using the same experimental approach, a family of enantiomerically pure oxonium ions, i.e., O-protonated 1-aryl-l-methoxyethanes (aryl = 4-methylphenyl ((5 )-49) 4-chlorophenyl ((5)-50) 3-(a,a,a-trifluoromethyl)phenyl ((5)-51) 4-(a,a,a-trifluoromethyl)phenyl ((S)-52) 1,2,3,4,5- pentafluorophenyl ((/f)-53)) and 1-phenyl-l-methoxy-2,2,2-trifluoroethane ((l )-54), has been generated in the gas phase by (CH3)2Cl -methylation of the corresponding l-arylethanols. ° Some information on their reaction dynamics was obtained from a detailed kinetic study of their inversion of configuration and dissociation. Figs. 23 and 24 report respectively the Arrhenius plots of and fc iss for all the selected alcohols, together with (/f)-40) of Scheme 23. The relevant linear curves obey the equations reported in Tables 23 and 24, respectively. The corresponding activation parameters were calculated from the transition-state theory. 

Table 23 Arrhenius parameters for the gas-phase intracomplex inversion of O-protonated 1-aryl-l-methoxyethanes...

Fig. 24 Arrhenius plots for the dissociation of O-protonated 1-aryl-l-methoxyethanes (aryl = 4-chlorophenyl ((S)-50) 3-(a,a,a-trifluoromethyl)phenyl ((S)-51) 4-(a,a,a-trifluor-omethyl)phenyl ((S)-52) 1,2,3,4,5-pentafluorophenyl ((R )-53) phenyl (R)-40)).

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