Different Olefins

The codimerization of acrylonitrile and methyl acrylate is catalyzed by ruthenium complexes under an atmosphere of hydrogen. Besides the hydrodimerization products of each monomer, up to 50% of the head-to-head codimerization products are formed [65] (Equation 47). 

Barlow reported some examples of codimerization using the catalyst dichlorobis(benzonitrile)palladium [49]. The reaction of styrene and methyl acrylate yielded the straight-chain isomer methyl lrans-5-phenyl-4-pentenoate (Equation 48). 

The codimerization of a functional olefin with a non-functional olefin is an interesting possibility for the synthesis of longer-chain monofunctional products. One example is the rhodium or rutheniixm chloride catalyzed codimerization of methyl acrylate with ethylene yielding linear monounsat-urated acids [48]. The main product is methyl-3-pentenoate (47%), but also esters of acids containing seven and nine carbon atoms were isolated in yields of 12 and 9%, respectively (Equation 49). 

Dichlorobis(benzonitrile)palladium is also an effective catalyst, and the codimers are formed in 47% yield [49]. The non-conjugated esters predominate in the mixture of products (60% trans- and 10% cis-3-pentenoate), but methyl ra 5-2-pentenoate is also present in substantial amounts of about 30% (Equation 50). 

The codimerization of methylacrylate and ethylene can be obtained with nickel catalysts, too [57]. A suitable catalyst is Ni(l 4-5- -CgHi3)PR3(S03CF3). 

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Olefin Sources. The choice of feedstock depends on the alcohol product properties desired, availabiUty of the olefin, and economics. A given producer may either process different olefins for different products or change feedstock for the same appHcation. Feedstocks beheved to be currentiy available are as follows. 

As the process branches to send the outline procedure through the organization, there is a possibility that significantly different local procedures will be developed. For example, the VP Operations Olefins passes the outline procedure to five different olefins departments where each department will develop its own procedure. It is likely that a common olefins procedure could be developed, reducing the level of effort needed to develop five local procedures. 

Metathesis is a catalyzed reaction that converts two olefin molecules into two different olefins. It is an important reaction for which many mechanistic approaches have been proposed by scientists working in the fields of homogenous catalysis and polymerization. One approach is the formation of a fluxional five-membered metallocycle. The intermediate can give back the starting material or the metathetic products via a concerted mechanism ... 

Squalene epoxidase, a key enzyme in the biosynthesis of cholesterol (9), epoxidizes one face of one of the three different olefins in squalene (7) to give squalene epoxide (8), which then cyclizes eventually to give cholesterol (9) (Scheme 1). The AD of squalene (7)... 

The use of the ionic liquid [bmim][BF4] further improved the Burgess epoxidation system [70]. Chan and coworkers found that replacement of sodium bicarbonate for tetramethylammonium bicarbonate and performing the reaction in [hmim][BF4] allowed for efficient epoxidation of a number of different olefins, including substrates affording acid-labile epoxides (such as dihydronaphthalene (99% yield) and 1-phenylcyclohexene (80% yield)). 

The olefin cross metathesis (CM) can be described as the intermolecular metathesis of alkylidene fragments between two different olefins [133]. It can be farther divided into three main subtypes cross metathesis, ring opening cross metathesis (ROCM) and enyne cross metathesis (ECM) (Scheme 3.9). 

Most investigations of the photocycloaddition of simple a,0-unsaturated carbonyls have involved the reactions of the ring compounds cyclopentenone and cyclohexenone. The photoaddition of 2-cyelohexenone to a number of different olefins has been reported by Corey and co-workers(94) ... 

The basis for this method lies in the fact that complexes of different olefins have different stabilities. For several common olefins, the order of stability of complexes analogous to Zeise s salt is... 

Information published from several sources about 1970 presented details on both the halide-containing RhCl(CO)(PPh3)2- and the hydride-containing HRh(CO)(PPh3)3-catalyzed reactions. Brown and Wilkinson (25) reported the relative rates of gas uptake for a number of different olefinic substrates, including both a- and internal olefins. These relative rates are listed in Table XV. 1-Alkenes and nonconjugated dienes such as 1,5-hexadiene reacted rapidly, whereas internal olefins such as 2-pentene or 2-heptene reacted more slowly by a factor of about 25. It should also be noted that substitution on the 2 carbon of 1-alkene (2-methyl-l-pentene) drastically lowered the rate of reaction. Steric considerations are very important in phosphine-modified rhodium catalysis. 

The selectivity problem is particularly important in the dimerization of two different olefins when, in addition to the required codimers, a mixture of the two possible homodimers may be produced. 

The reactivities of different olefins toward seodecylsulfonic peracid (values of k and k2) are listed in Table 12.5. 

Unsymmetrical dimers are accessible through the coelectrolysis of different olefins (Table 7, number 11). Coupling can also be achieved by the addition of anodically generated radicals with subsequent dimerization of the adduct radicals (additive dimerization, see Section 5.3.3). 

Figure 3.31 Conversion versus time in the hydrogenation of two different olefinic alcohols (hex-2-en-1-ol and hex-5-en-1-ol) with two different catalysts (a) Rh/Si02 (b) [Rhsjsfri SnBu)/...

The organoactinide surface complexes exhibited catalytic activities comparable to Pt supported on sihca [at 100% propylene conversion at —63°C, >0.47s (U) and >0.40 s (Th)], despite there being only a few active sites (circa 4% for Th, as determined by CO poisoning experiments and NMR spectroscopy) [92]. Cationic organoactinide surface complexes [Cp An(CH3 ) ] were proposed as catalytic sites. This hypothesis could be corroborated by the use of alkoxo/hydrido instead of alkyl/hydrido surface ligands, which led to a marked decrease of the catalytic activity, owing to the oxophilic nature of the early actinides [203, 204]. Thermal activation of the immobihzed complexes, support effects, different metal/ligand environments and different olefins were also studied. The initial rate of propylene conversion was increased two-fold when the activation temperature of the surface complexes under H2 was raised from 0 to 150°C (for Th 0.58 0.92 s" ). 

The selection of steam cracker feedstock is mainly driven by market demand as different feedstock qualities produce different olefins yields. One of the commonly used feed quality assessment methods in practice is the Bureau of Mines Correlation Index (BMCI) (Gonzalo et al., 2004). This index is a function of average boiling point and specific gravity of a particular feedstock. The steam cracker feed quality improves with a decrease in the BMCI value. For instance, vacuum gas oil (VGO) has a high value of BMCI and, therefore, is not an attractive steam cracker feed. The commonly used feedstocks in industry are naphtha and gas oil. 

When a pure alkene is polymerized and only one form of the olefin is possible or when it is definitely known that only one molecular form is reacting under the polymerizing conditions, there is no need to decide which molecule is the acceptor and which the donor molecule. On the other hand, when two different olefins are copolymerized, it is necessary... 

Pd/Cu zeolite Y associations were found to be selective catalysts for oxidation of olefins in the presence of steam at temperatures ranging from 373 to 433K [22-30]. Acetone and acetaldehyde were obtained by propylene and ethylene oxidation, with selectivities of at least 90%. Neither Pd/Y nor Cu/Y showed good activity in these reactions. The conversion of different olefins under the same experimental conditions decreases in the following order [23] ethylene > propylene > 1-butene > cis-2-butene - trans-2-butene. 

The results of the various published known methods for molybdenum-catalyzed epox-idation of different olefins are presented in Table 22. 

Fig. 6. The decay with distance down a flow tube of Oa Aj) in the presence of equal concentrations of different olefins.44...

The contrast between the behavior of recoil atoms and those produced in the carbon arc may reflect the larger kinetic energy of the former. However, even in solid xenon at low temperatures the recoil atoms yield no spiropentane from ethylene.17 It has been suggested that the initial carbon atom-olefin adducts may partition themselves differently for different olefins.17... 

The isomerization of the olefin prior to its hydroformylation has been the explanation of this question (3) and the formation of isomeric aldehydes was related to the presence of isomeric free olefins during the hydroformylation. This explanation, however, is being questioned in the literature. The formation of (+) (S) -4-methylhexanal with an optical yield of more than 98% by hydroformylation of (+) (S)-3-methyl-l-pentene (2, 6) is inconsistent with the olefin isomerization explanation. Another inconsistency has been the constance of the hydroformylation product composition and the contemporary absence of isomeric olefins throughout the whole reaction in hydroformylation experiments carried out with 4-methyl-1-pentene and 1-pentene under high carbon monoxide partial pressure. The data reported in Ref. 4 on the isomeric composition of the hydroformylation products of 1-pentene under high carbon monoxide pressure at different olefin conversions have recently been checked. The ratio of n-hexanal 2-methylpentanal 2-ethylbutanal was constant throughout the reaction and equal to 82 15.5 2.5 at 100°C and 90 atm carbon monoxide. 

Table V. Influence of the Reaction Conditions on the Optical Yield in the Hydroformylation of Different Olefins with HRh(CO) (P< 3)3 and ( —)-DIOP pn2 = pco...

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