Hexene production

The enthalpies of formation of the monoolefin hexene products are derived from Reference 11. 

G-Values for Hexene Products from Irradiated re-Hexene ... 

Figure 3.22 Structures of four similar titanium catalyst precursors with different symmetries, used in the polymerization of 1-hexene, and the corresponding isotactic poly(hexene) product yields.

It is also clear that double-bond-shift is relatively facile on the nickel-silica-alumina catalysts. Double-bond shift may occur on the nickel cation centers or on the silica-alumina support or on both14. The hexene products formed from ethene are as expected for a reaction sequence involving (1) dimerization of ethene to but-l-ene etc, (2) double-bond-shift of but-l-ene to a but-2-ene mixture, and (3) reaction of but-2-ene with a further ethene... 

Table n. Chromatographic Analysis of Major Hexene Products From Propylene Conversion Over SAPO Catalysts (Propylene Inlet Pressure= 16.2 KPa)... 

Figure 220 is a plot of the logarithm of the mol% a-olefin produced in the presence of BEt3 against the carbon number of the olefin. In this format, the Schulz-Flory distribution stands out clearly as a straight line on which the data for all the olefins but 1-hexene fall. The 1-hexene product clearly stands out as a spike off the Schulz-Flory background. 

Reaction temperature also increased the selectivity for 1-hexene production. In one experiment the reaction temperature was increased from 80 °C to 95 °C, and BEt3 cocatalyst was adjusted to hold density at 0.940. This increased the molar ratio of 1-hexene to 1-butene produced from 0.44 up to 0.90, thus doubling the selectivity. 

The selectivity of 1-hexene production, relative to the Schulz-Flory background, here measured as the molar ... 

When metathesis is effected with tra i-2-pentene, rather than cis-, and (diphenylcarbene)pentacarbonyltungsten is the initiator, the 2-butene and 2-hexene products are largely trans. The stereospecificity (73-83% trans) is not as great as for cw-olefin metathesis, but it is appreciable (63). The ratios of the stereoisomers in the products are close to the equilibrium ratios, but they probably are not determined by the products equilibrating, for in the short time the metathesis was run to determine the stereochemistry of the initial product, the precursor, tranj-2-pentene, underwent only negligible isomerization. The stereochemistries therefore are determined by the kinetics, which in turn should be affected by conformational factors similar to those in Scheme... 

Pulsed-laser studies with W(CO)jL (L = pyridine or piperidine) have essentially confirmed the earlier observations. This work also showed that a solvent complex is formed within 10 ps of the laser flash and this "intermediate" is the ultimate source of the substitution products. These authors also reported that if 1-hexene is the entering ligand, then the first product has W(CO>5 complexed to the "alkyl portion" of the hexene and this species rearranges in about 10 ns to the T -hexene product. These observations may be relevant to those of Stoutland and Bergman on the addition of ethylene to Ir(Cp )(PMe3) discussed in Section 5.5. 

Extrusion is the reverse reaction of insertion (CN +1, VE +2, ON unchanged). The reaction plays a very important role in ethylene oligomerization according to the insertion/elimination mechanism as the so-called P-H-elimination. Scheme 6.16.6 illustrates this elementary step for the extrusion of a 1-hexene product from a Ni-hexyl complex. The extrusion step is followed by 1-hexene dissociation from the complex (see above) to finally liberate the 1-hexene product. Below, in Scheme 6.16.8, the extrusion step is shown as part of a more complex reaction sequence for the liberation of a 1-alkene product from a chromium metallacyclic intermediate. 

The process given in Figure B.11.1 is based on the liquid-phase catalytic codimerization of C3 and C4 olefins using an organometallic catalyst. This catalyst is slurried with a small volume of the hexenes product and fed to the reactor with the feed streams. The volume of the catalyst stream is small conpared with the other streams and is not included in the material balance given in Table B.11.1. In 1976 (CEPCI = 183), consumption of catalyst amounted to 9.5/1000 kg of 1-heptene product [1]. 

I Stereochemisty of the proton at C6 of the bicylo[3.1.0]hexene products endo only implies a benzvalene intermediate. 

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