Reaction of free [3H]phenylium ion, generated from nuclear decay of p-3H2C6H4 (I) in the presence of gaseous MeX (X = F, Cl, Br) at 30-760 Torr partial pressures, yields the corresponding labeled halobenzenes (F, 32-65%; Cl, 80-90%; Br, 84-91%), together with minor amts. of PhMe, MeC6H4X, PhCH2X, and fragmentation products. The resulting tritiated halobenzenes are characterized by significant 3H scrambling over the ring (ortho < meta < para), whose extent increased appreciably when the reaction is carried out at low MeX pressures. These results are consistent with previous expts. involving I decay in MeOH(g), and are interpreted in terms of a general mechanism involving a relatively fast (k ≃ 107 s-1) automerization sequence in the [3H]phenylium ion via consecutive 1,2-H shifts. An alternative interpretation of the MeOH data was excluded.
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|Titolo:||Automerization of gaseous phenylium ions. Direct evidence from the phenylation of methyl halides|
|Data di pubblicazione:||1983|
|Appartiene alla tipologia:||01a Articolo in rivista|