1,5-cyclo-octadiene hydrogenation

Similar low activities were found in the hydrogenation of 1-octene [47]. The use of [Ni(PPh3)2I2] in the hydrogenation of norbomadiene resulted in considerable amounts of nortricyclene, via transannular ring closure, whereas 1,5-cyclo-octadiene yielded bis-cyclo-[3.3.0]oct-2-ene. According to these authors, the re-... 

By hydrogenation of the diene, the cyclo-octadiene precatalyst can easily be transformed into the solvent complex. 

In contrast, 1,5-cyclo-octadiene remains coordinated during the catalytic cycle of hydrogenation of phenylacetylene to styrene, catalyzed by the related iridium complex [Ir(C0D)( Pr2PCH2CH20Me)]BF4. This complex, which contains an ether-phosphine-chelated ligand, catalyzes the selective hydrogenation reaction via a dihydrido-cyclo-octadiene intermediate. The reaction is first order in each of catalyst, phenylacetylene and hydrogen [11] the proposed catalytic cycle is shown in Scheme 2.3. 

Soluble and stable iridium nanoparticles (3.0 0.4nm diameter) have been prepared by reduction of the polyoxoanion-supported lr(l) complex (n-Bu4N)sNa3 [(C0D)lr(P2WisNb3062)] (COD = 1,5-cyclo-octadiene) with molecular hydrogen in... 

Hence, two methods are available that can be applied to follow nanoparticles formation and growth (i) an indirect method that utilizes the consumption of molecular hydrogen pressure versus time and (ii) a direct method that follows the loss of precursor by the 1 1 conversion of its cyclo-octadiene ligand to cyclo-octane by GLC measurements. The mechanism developed by Watzky and Finke suggests that the nanoparticles act as Hving-metal polymers -a concept that could be used to obtain particles with defined sizes simply by adding the appropriate amounts of catalyst precursors [32]. 

The hydrogenation of 1,5-cyclo-octadien (COD) to cyclo-octene (COE) is performed in a slurry reactor. The reaction is relevant because the product is an intermediate for the production of special polymers. However, this reaction suffers from the drawback that the hydrogenation does not stop at cyclo-octene, because a full hydrogenation to cyclo-octane (COA) is possible, as shown in Figure 4.1.12. 

Figure 4.1.12 Reaction scheme of the hydrogenation of 1,5-cyclo-octadien.

Dimerization of butadiene is used for the selective formation of 1,5-cyclo-octadiene (1,5-COD), which on selective hydrogenation gives cyclooctene. By ring-opened metathesis polymerization of cyclooctene a specialty polymer is obtained (see Section 7.6.1). Hulls sells this polymer as Vestenamer . 

High catalytic activities, with turnovers of up to 9(X) cycles min , is displayed in the transfer hydrogenation of a,p-unsaturated ketones, such as benzylideneacetone and chalcone, using 2-propanol and catalytic amounts of [Ir(3,4,7,8-Me4-phen)COD]Cl (phen = 1,10-phenanthroline COD = 1,5-cyclo-octadiene) in a weakly alkaline medium. Other Ir-chelated complexes are also active catalysts in this reaction, with over 95% selectivity for the 1,4-reduction mode. Divalent lanthanide derivatives, such as Sml2 or Ybh in stoichiometric quantities, in THF and t-butyl alcohol or methanol reduce ethyl cinnamate and cinnamic acid to give the saturated derivatives. " Similarly, 3-methylcyclohexenone is reduced to 3-methylcyclohexen-l-ol in 67% yield, but a,p-unsaturated aldehydes are nonselectively reduced with these systems. 

Catalytic hydrogenation of copolymers was performed in a volumetric microhydrogenation apparatus. Tetramethylene sulfone is used as solvent and 10% palladium-on-charcoal is the catalyst. In each case the reaction is allowed to run for 18 hr to ensure complete reaction. The infrared spectrum of I showed the pertinent peak as listed in Table XI. For comparison, significant peaks of cis,cis-1,5-cyclooctadiene are also listed in Table XI. The co-polymerization of sulfur dioxide and 1,5-cyclo-octadiene is shown in Table XII. 

On an unspecified supported palladium catalyst at 323 K, 1,5-cyclo-octadiene isomerised to the 1,3-form at about the same rate as it was hydrogenated 5tot was about 90%, and some mathematical modelling was attempted. Other cyclic dienes have also been examined. ... 

Since the 1970s, palladium and platinum complexes with dibenzylideneacetone Pd(dba)2 and M2(dba)3 (M = Pd, Pt) have been known to react under mild conditions with either hydrogen or carbon monoxide, with the formation of a metal [211]. Indeed, there exists a long series of examples where CO and H2 have been used to decompose organometallic precursor molecules [173-177,179-181,183,184,186-188, 212-216]. As an example, the decomposition Ru(COD)(COT) (COD = cyclo-octadiene COT =cydo-octatriene) in an atmosphere of hydrogen is worthy of mention [189,190]. (Scheme 3.20). In this case, the precursor molecule is dissolved in a methanol-THF mixture and is contacted with H2 (3 bar pressure) at room temperature for at least 45 min. Depending on the nature of the MeOH-THF mixture, the Ru particle size can be designed between 3 and 86 nm. 

Nickel. Product analysis gives some information on the catalytic role of Ni(CN)2L2 , where L = CN, phen, etc., in the hydrogenation and isomerisation of dimethyl maleate and of 1,5-cyclo-octadiene. ... 

The air-stable complex [Ir(cyclo-octadiene)(PMePh2)2]PF6, after activation with hydrogen, isomerizes allyl ethers to the corresponding frans-propenyl ethers at room temperature with very high stereoselectivity ( 97%) and in high yield (3=95%) [equation (6)]. This appears to be the first stereoselective conversion of alkyl ethers into rrans-propenyl ethers, but the reaction is limited to primary allyl ethers, secondary allyl ethers being unaffected even at 65 °C. 

The metal-catalysed autoxidation of alkenes to produce ketones (Wacker reaction) is promoted by the presence of quaternary ammonium salts [14]. For example, using copper(II) chloride and palladium(II) chloride in benzene in the presence of cetyltrimethylammonium bromide, 1-decene is converted into 2-decanone (73%), 1,7-octadiene into 2,7-octadione (77%) and vinylcyclohexane into cyclo-hexylethanone (22%). Benzyltriethylammonium chloride and tetra-n-butylammo-nium hydrogen sulphate are ineffective catalysts. It has been suggested that the process is not micellar, although the catalysts have the characteristics of those which produce micelles. The Wacker reaction is also catalysed by rhodium and ruthenium salts in the presence of a quaternary ammonium salt. Generally, however, the yields are lower than those obtained using the palladium catalyst and, frequently, several oxidation products are obtained from each reaction [15]. 

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