7642-04-8Relevant articles and documents
Photochemistry of Alkenes. 7. E/Z Isomerization of Alkenes Sensitized with Benzene and Derivatives
Snyder, John J.,Tise, Frank P.,Davis, Robert D.,Kropp, Paul J.
, p. 3609 - 3611 (1981)
Contrary to numerous previous reports placing the (E/Z)pss ratios from benzene-sensitized isomerization of various alkenes at unity, the (E/Z)pss ratios for alkenes 1-4 (Table I) have been found to (a) differ from unity, with the less highly strained isomer predominating, (b) vary depending on the structure of the alkene, and (c) bear an apparently linear relationship with the triplet excitation energy of the sensitizer.The results are tentatively interpreted in terms of "nonvertical" energy transfer, with transfer occuring more efficiently to the thermodynamically less stable isomer.Possible difficulties with the quantitative aspects of this interpretation are dicussed.Of several sensitizers evaluated for efficiency in effecting E/Z isomerization of 3,4-dimethyl-2-pentene (2) (Table III), p-xylene and phenol were found to be superior.The latter has the added advantage of being easily separated from the alkene by extraction with base.
Designing and synthesis of phosphine derivatives of Ru3(CO)12 – Studies on catalytic isomerization of 1-alkenes
Pandya, Chayan,Panicker, Rakesh R.,Senjaliya, Parth,Hareendran, M.K. Hima,Anju,Sarkar, Sibasis,Bhat, Haamid,Jha, Prakash C.,Rao, Koya Prabhakara,Smith, Gregory S.,Sivaramakrishna, Akella
, (2021/01/12)
A comparative investigation on the isomerization reactions of 1-alkenes to their corresponding 2-alkenes catalyzed Ru3(CO)12 (1), Ru3(CO)9(PEt3)3 (2) and Ru3(CO)10(dppe) (3), (where dppe = 1,2-bis(diphenylphosphino)ethane) is described. Both the complexes of types 2 and 3 were characterized by all analytical and spectroscopic data. The molecular structure of 2 was confirmed by single-crystal X-ray analysis. It is observed that the nature of phosphine ligands plays an important role in the isomerization of 1-alkenes. When the chelated diphosphine is used, the internal isomerization reaction by [Ru3(CO)10(dppe)] (3) is completed relatively in less time compared to other derivatives. As per the DFT calculations, the observed reaction rate for the alkene isomerization may be explained based on the relative stability of 1, 2, and 3. The CO abstraction step is highly feasible in 3, the least stable among the three, thus the reaction occurs at the highest rate. Due to the increased relative stability from 2 to 1, the reaction requires more time at elevated temperatures and the rate decreases as a consequence.
Steric and Electronic Effects of Phosphane Additives on the Catalytic Performance of Colloidal Palladium Nanoparticles in the Semi-Hydrogenation of Alkynes
Staiger, Lena,Kratky, Tim,Günther, Sebastian,Tomanek, Ondrej,Zbo?il, Radek,Fischer, Richard W.,Fischer, Roland A.,Cokoja, Mirza
, p. 227 - 234 (2020/10/14)
We report on the influence of phosphanes on the catalytic activity and selectivity of colloidal, tetraoctylammonium bromide (TOAB) stabilised palladium nanoparticles (NPs) in the semi-hydrogenation of alkynes to olefins. Full characterisation of the catalytic system (HRTEM, EDX, XPS, IR, NMR) confirmed the formation of spherical particles with a narrow size distribution (1.9±0.5 nm). The catalytic performance of the Pd NPs in the semi-hydrogenation of 1-octyne, 2-octyne and phenylacetylene to the respective olefins and the influences on the selectivity was investigated. The system shows high activities and selectivities at mild conditions (0 °C and 1.0 bar H2 pressure). It was shown that generally, phosphanes lead to an increase of both the reaction rate and selectivity towards the olefin where both steric and electronic effects of the ligand play a crucial role for the catalyst performance. A moderate steric demand of the ligand with a rather weak σ-donating ability turned out to give the highest catalytic performance.
