Hex-l-ene, hydrogenation

Figure 3. A comparrison of the hex-l-ene hydrogenation behaviour of the two nanoparticle catalysts Ag4Rul2 and Cu4Rul2. Note how the silver containing catalyst is significantly superior in terms of TOF in the early stages of the reaction (i.e. no induction time).

Similarly, reactions between Ag+ ions and [Ru5C(CO)14]2 have given [Ag3Ruio(C)2( r-Cl)(CO)2g]2 (403), which retains the square pyramidal Ru5C core.581 The Cl atom is presumably derived from the [ppn]Cl or [AsPh4]Cl used to provide counter-cations for this large anion. When anchored inside mesoporous silica (MCM-41), the intact cluster core acts a catalyst for hex-l-ene hydrogenation. 

The cyclooctene dimer [IrCl(C8H]4)2] can selectively hydrogenate cy-clooctene in mixtures with hex-l-ene, and an unsaturate route [Eq. 1(b)] via a monomeric olefin complex was demonstrated (181). The pentamethylcyclopentadienyl dimer was mentioned at the end of Section II, B, 2. 

Adsorption of hex-l-ene, a mixture of cis- and frans-hex-2-ene, and c/s-hex-3-ene on nickel—silica results in identical infrared spectra [83]. Addition of hydrogen results in an intensification of the spectrum suggesting that the initial spectrum results from dissociatively adsorbed species, a conclusion substantiated by the observation that the gas in equilibrium with the surface during the initial adsorption contains isomerised hexenes. Evacuation of the hydrogen causes a decrease in intensity and the reappearance of the initial spectrum. 

The catalytic performance of the supported bimetallic nano-particles in the hydrogenation of unsaturated molecules was tested on a wide variety of unsaturated species hex-l-ene, phenyl acetylene, diphenyl acetylene, trans-stilbene, cis-cyclooctene and D-limonene. The highly efficient hydrogenation of hex-1 -ene was accompanied by the isomerisation reaction to cis-and trans-hex-2-ene, which were subsequently hydrogenated (albeit at a much slower rate) as reaction ensued. 

In concerted E2 eliminations from monofluorides a predominance of Hofmann orientation is observed, as is consistent with a poor leaving group and a transition state with high charge on the /2-carbon atom, that is, orientation is controlled by the relative acidities of the /1-hydrogens.6,7 2-Fluorohexane (1) when treated with sodium methoxide in methanol gives both hex-l-ene and hex-2-cne in yields of 69 and 31 %, respectively.6... 

It was the virtually identical infrared spectra from the hex-l-ene, hex-2-ene, and hex-3-ene isomers when adsorbed on Ni/Si02 (7) that first led Eischens and Pliskin to the conclusion that the finely divided metal catalysts involve isomerization of the monohexenes. Their mutual spectrum and that obtained after hydrogenation are shown in Fig. 24B. Similar spectra at higher resolution were obtained by Shopov, Andreev, and Palazov (162) and by Erkelens and Liefkens (262) these are illustrated in Figs. 24C and D, respectively. 

Fig. 24. Infrared spectra from hex-l-ene adsorbed near room temperature before and after hydrogenation on (A) Pt/Al203 (171) (B) Ni/Si02 (7) (C) Ni/SiOi (162) and (D) Ni/SiOj on a hydrogen-covered surface (upper spectrum) and on a hydrogen-depleted metal surface (lower spectrum) (262).

The desired number may be recognized as the difference of the enthalpies of hydrogenation of cubene and bicyclo[2.2.0]hex-l-ene and found to be ca 50 17 kJmol-1 endothermic. In that cubene is more rigid than the bicyclohexene, it is surprising that the hydrogenation enthalpy is smaller for the former than the larger. Alternatively, consider reaction 22. 

The crystal structure of the square planar complex [Ir(Cl)(Cu)(Ph2PC6H4NMe2)] (53) has been determined. IR and31P NMR spectra for complexes (53), (54) and (55) have suggested that all three complexes possess the same stereochemistry.138 It was also observed that these complexes are more effective than Vaska s complex for the isomerization of 1-hex-l-ene under hydrogenation conditions.138... 

Striking hydride derivatives are formed, which are efficient catalysts for the homogeneous hydrogenation of hex-l-ene (Figure 13.10) ... 

In addition, as esters, phthalate plasticisers are susceptible to hydrolysis when exposed to strongly acidic or alkaline environments. Acid hydrolysis causes the formation of crystalline phthalic acid, volatile 2-ethyl hex-l-ene and 2-ethylhexanol. Acidic environments may develop when the PVC polymer degrades to form hydrogen chloride. Oxygen attack on alkyl groups in the DEHP molecule also results in the formation of phthalic acid. 

Intramolecular hydrogen abstraction in 2-alkoxynaphtho-l,4-quinones in the presence of olefins (hex-l-ene, hept-l-ene, oct-1-ene, cyclohexene, cyclo-octene,... 

The concentrations of phosphine and CO can markedly alter the equilibria shown in Scheme 1 and hence the reaction pathway may be affected, giving rise to differing selectivities. This has been discussed by Hjortkjaer and illustrated by variation of phosphine and CO concentrations in hex-l-ene hydroformylation. At constant concentrations of alkene, [RhH(COXPPh3)3] and hydrogen (0.05 MPa) and at 0.1 MPa total pressure (balance N2) the CO partial pressure was varied from 0.01 to 0.05 MPa with from zero to six molar equivalents of excess phosphine added. At phosphine Rh levels of seven to nine the hydroformylation rate was zero order with respect to CO for pCO... 

Titanium. Catalyses of hydrogenation of alkenes, alkynes, carbonyl-, and nitro-compounds have been described. The effect of the nature of the ligand L and of the alkene to be reduced on reactivity in catalytic hydrogenation by Ti(7r-C5H5)2L2 has been quantitatively studied. The dependence of rate constants on solvent for reduction of decene in the presence of Ti(7r-C5H5)Me+ is interpreted in terms of electrostatic interaction between the active ionic species and the solvent. There is also a thermochemical report relevant here, and that is of a determination of the heats of mixing of cyclohexene and of hex-l-ene with titanium tetrachloride. The heats of mixing are close to zero, which implies very small heats of complex formation between these alkenes and titanium. ... 

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