The aim of this project consists of detennining the feasibility of a new tandem reaction comprising isomerization and telomerization steps starting from internal diolefins. This type of reactions achieves not only a minimization 9fthe number of steps but also potentially reduces waste fonnation and process capital costs, thus fulfilling the main objectives of Green Chemistry towards the design of sustainable processes. Telomerization is a 100% atom efficient route to the fonnation of functionalized long chain molecules. However, only telomerization of tenninal . conjugated dienes has been reported which limits its applications due to the thennodynamically unfavourable presence of tenninal dienes in natural feedstocks. If proved feasible, the proposed tandem reaction would open opportunities for the utilization ofnew feedstocks and a potentially significant industrial impact. Titanate nanotubes was found to be a good support for metal catalysts (Pd, Rh, Ru), showing high activity in the isomerization of diolefins and very high selectivity for the reaction with allylbenzene. A novel Ru-PPh3-resin catalyst was also highly active in diolefins isomerization (including linoleic acid) with similar catalytic activity than homogeneous catalysts and the possibility of being reused without loss of activity. Screening of homogeneous catalysts based on phosphorus and carbene ligands was carried out for the telomerization reaction and the influence of different operation conditions such as temperature, initial concentration and the nature of nucleophiles was investigated. Heterogeneous catalysts based on DVBresins were also studied, revealing an unusual selectivity to tail-to-head products by Pd-(dvds)-PPh3-resin in the reaction of isoprene with methanol. The telomerization reaction was extended to 1,3-hexadiene when long-chain alcohols are used as nucleophiles and Pd(Imes)(dvds) as catalyst, opening opportunities for long-chain reactants. Finally, the feasibility of tandem reactions was successfully demonstrated with the best results obtained with homogeneous isomerization and telomerization catalysts in the presence of free carbene ligands in the reaction medium.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:485154 |
| Date | January 2007 |
| Creators | Torrente Murciano, Laura |
| Publisher | University of Bath |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
Page generated in 0.0132 seconds