I. Tunon et al., TRANSITION STRUCTURES OF THE FRIEDEL-CRAFTS REACTION IN SOLUTION, Journal of the Chemical Society. Faraday transactions, 90(12), 1994, pp. 1757-1761
Citations number
24
Categorie Soggetti
Chemistry Physical","Physics, Atomic, Molecular & Chemical
We have studied the Friedel-Crafts reaction between HF and CH4 both un
catalysed and catalysed by BF3. Stationary structures have been locate
d and characterized at the HF/6-31 + G level of theory both in the gas
phase and in solution. For the uncatalysed process, by using the cont
inuum model, we have located a transition structure in solution which
is different from that in the gas phase. This structure is also differ
ent from that obtained including the solvation effects in the reaction
path constructed in the gas phase. Discrete calculations including tw
o solvent molecules agree with the results obtained with the continuum
model. Two different mechanisms have been investigated for the cataly
sed process, an acid catalysis and a bifunctional one. Solvent effects
also produce important changes in the transition structures of the ca
talysed processes from both the nuclear and the electronic points of v
iew. The relative stability of the transition states of the acid and b
ifunctional catalysis is changed, showing that the solvent can modify
the mechanism in solution, compared with the gas phase, for the cataly
sed process.