7319-00-8Relevant articles and documents
Isomerization of 1,5-hexadiene catalyzed by bis-(cyclopentadienyl) lanthanide schiff base/NaH systems; Ln = Sm, Dy, Y, Er
Yousaf, Muhammad,Qian, Yanlong,Saeed, Muhammad Khalid
, p. 81 - 85 (2007/10/03)
Catalytic isomerization of 1,5-hexadiene by Cp2Ln Schiff base/NaH (Schiff base = C14H14NO2, Ln = Sm, Dy, Y, and Er) systems was studied. The isomerization resulted in a mixture of 1,4-hexadiene, 2,4-hexadiene, 1,3-hexadiene, methylene-cyclopentane, and methylcyclopentene. 1,4-Hexadiene and methylenecyclopentane were the intermediate products, while 2,4-hexadiene and methylcyclopentene were the end-products. The effects of the nature of catalyst, temperature, amount of the catalyst, time and solvent, on the isomerization rate and product composition were also studied. The ratio of the linear to the cyclic product in the reaction depended on the amount of catalyst used.
Homogeneous Catalysis on Metal Clusters. The Isomerization and Selective Hydrogenation of Dienes, Alkenes, and Alkynes in the Presence of and . Spectroscopic Identification of the Reaction Intermediate...
Castiglioni, Mario,Giordano, Roberto,Sappa, Enrico,Tiripicchio, Antonio,Camellini, Marisa Tiripicchio
, p. 23 - 30 (2007/10/02)
The complexes and catalyze under homogeneous conditions the hydrogenation of one double bond of dienes and show selectivity in the hydrogenation of triple and double C-C bonds; non-conjugated dienes are isomerized.Experimental evidence suggests that the cluster acts as a catalyst.Complexes and have been isolated in the reaction solutions.The former complexes have been identified by spectroscopy and the latter by X-ray diffraction methods.A reaction path is proposed.Crystals of are monoclinic, space group P21/n, with unit-cell dimensions a=10.960(7), b=17.064(8), c=10.162(5) Angstroem, β=106.07(2) deg, and Z=4.The structure was determined from diffractometer data by Patterson and Fourier methods and refined by full-matrix least squares to R=0.048.In the complex an allylic ligand (derived from a pentadiene) co-ordinated to a triangular osmium cluster has been found; although this type of structure has already been reported, this is the first osmium complex obtained by reaction with a diene.
Solution-Phase Photodecarbonylation of the Bicyclohexan-3-one System
Cooke, Robert S.,Lyon, Gregory D.
, p. 7317 - 7322 (2007/10/02)
Direct irradiation of solutions containing (-)-thujone (6) or (+)-isothujone (7) affords trans- and cis-5-methylene-6-methylhept-2-ene (8 and 9) in quantitative yield.The epimeric ketones give identical produc mixtures, which are somewhat temperature dependent.The product ratio remains constant throughout irradiation, and appropriate control experiments indicate that the observed diene mixture does not represent a rapidly established photostationary state.Limited epimerization of the ketones is observed although this process is much less efficient than extrusion of carbon monoxide.Quenching studies employing piperylene indicate that the majority of the decarbonylation products originate from a short-lived triplet state.Direct irradiation of solutions containing exo- or endo-2-methylbicyclohexan-3-one (10 or 11) yields trans- and cis-hexa-1,4-diene (12 and 13) in high yield.Again the epimeric ketones give identical product mixtures, which are slightly temperature dependent.Direct irradiation of solutions containing exo,exo-, exo,endo-, or endo,endo-2,4-dimethylbicyclohexan-3-one (16, 15, or 14) affords similar, but not identical, mixtures of trans,trans-, trans,cis-, and cis,cis-hepta-2,5-diene (17, 18, and 19) in high yield.Each of these product ratios is somewhat temparature dependent.These data are explained in terms of a mechanism involving biradical intermediates.Excitation followed by intersystem crossing leads to a short-lived triplet state which undergoes Norrish I cleavage toward the more substituted α position.The diene products are formed upon synchronous cleavage of the cyclopropane bond and loss of carbon monoxide.If internal rotation in the intermediate is rapid with respect to decay, the observed product ratios may be rationalized.Inefficient reclusure of the biradical species leads to limited epimerization of the bicyclohexan-3-ones.
