Abstract:
The kinetics of the reactions between triethylaluminium and phenylacetylene have been studied in cyclohexane between 313 and 333 K. Two reactions are observed; metallation, which proceeds by the bimolecular reaction of dimeric triethylaluminium and phenylacetylene with a rate coefficient k2= 106.8 ± 1.5 e–(64000 ± 2900K/8.314T) dm3 mol–1 s–1, and addition which proceeds by way of an alkyne π-complex (I). The equilibrium constant for the formation of (I) has been estimated. The rate controlling step of the addition reaction is a rearrangement of (I), through a four-centre transition state, with a rate coefficient k1= 1011.6 ± 0.9 e–(94000 ± 2500K)/8.314T) s–1.
