Computational study of isoprene telomerization catalized by Pal·ladium complexes

Identifier:  TFG:1194

Handle: https://hdl.handle.net/20.500.11797/TFG1194

Authors:  Gómez Lleberia, José Alberto

Abstract:
Abstract Experimentally is found that the regioisomer resulting from the reaction of telomerisation of isoprene with nucleophiles strongly depends on the proticity of the solvent; therefore this fact is an indicator that the mechanism of the reaction is sensitive to the solvent acidity. In order to explore the possible mechanisms that can take place during the course of the reaction under protic and aprotic conditions, a DFT study has been carried out, considering as nucleophile source dimethylamine, as protic solvent methanol and as aprotic solvent dimethylamine. Under aprotic conditions two mechanisms have been determined, the so called zwiterionic mechanism and coordinative mechanism, being both mechanisms, according to the calculations, competitive between them. The zwiterionic mechanism is selective towards the E product, whereas the coordinative mechanism is selective towards the Z product; this fact is in agreement with the experimental fact that an isomeric mixture of E/Z isomers results under aprotic conditions. Under protic conditions also two mechanisms have been determined, the so called coordinative and non-coordinative mechanisms, being the non-coordinative mechanism the most active one. The non-coordinative mechanism is selective towards the E product, whereas the coordinative mechanism is selective towards the Z product; as the non-coordinative mecanisme is the most active one the theoretical prediction is the E product to be formed mainly. These facts are also in agreement with experimental data: under protic conditions an isomèric mixture with a high E/Z ratio is obtained.