Catalytic olefin

Fig. 2 Ruthenium-NHC complexes active in catalytic olefin metathesis...

An area in which catalytic olefin metathesis could have a significant impact on future natural product-directed work would be the desymmetrization of achiral molecules through asymmetric RCM (ARCM) or asymmetric ROM... 

Keii T, Soga K (1990) Catalytic Olefin Polymerization. Elsevier, Lausanne... 

It should be noted here again that the catalytic reaction does not involve a change of valence of the metal. In general, catalytic olefin addition reactions that involve a hydride transfer do not require change of valence in the metal catalyst. On the other hand, carbon-carbon bond formation by coupling reactions which involve electron shifts, such as in Wilke s Ni°-catalyzed butadiene oligomerization reaction [Eq. (1)], requires a valence change on the metal. 

Experiments with trichlorosilane-d, Cl3SiD, were most instructive about side reactions that can take place in the hypothetical catalytic olefin PtH(—S ) species during hydrosilation. Although trichlorosilane-d and methyldichlorosilane showed no exchange of deuterium and hydrogen at 100°C during many hours in the absence of a catalyst, traces... 

The reaction of olefin epoxidation by peracids was discovered by Prilezhaev [235]. The first observation concerning catalytic olefin epoxidation was made in 1950 by Hawkins [236]. He discovered oxide formation from cyclohexene and 1-octane during the decomposition of cumyl hydroperoxide in the medium of these hydrocarbons in the presence of vanadium pentaoxide. From 1963 to 1965, the Halcon Co. developed and patented the process of preparation of propylene oxide and styrene from propylene and ethylbenzene in which the key stage is the catalytic epoxidation of propylene by ethylbenzene hydroperoxide [237,238]. In 1965, Indictor and Brill [239] published studies on the epoxidation of several olefins by 1,1-dimethylethyl hydroperoxide catalyzed by acetylacetonates of several metals. They observed the high yield of oxide (close to 100% with respect to hydroperoxide) for catalysis by molybdenum, vanadium, and chromium acetylacetonates. The low yield of oxide (15-28%) was observed in the case of catalysis by manganese, cobalt, iron, and copper acetylacetonates. The further studies showed that molybdenum, vanadium, and... 

CATOFIN [CATalytic OleFIN] A version of the Houdry process for converting mixtures of C3 - C5 saturated hydrocarbons into olefins by catalytic dehydrogenation. The catalyst is chromia on alumina in a fixed bed. Developed by Air Products Chemicals owned by United Catalysts, which makes the catalyst, and licensed through ABB Lummus Crest. Nineteen plants were operating worldwide in 1991. In 1994, seven units were used for converting isobutane to isobutylene for making methyl /-butyl ether for use as a gasoline additive. 

Auriemma, F. Talarico, G. Corradini, P. In Progress and Development of Catalytic Olefin Polymerization. Sano, T. Uozumi, T. Nakatani, H. Terano, M. (Eds.). Technology and Education Publisher, Tokyo, 2000, p. 7. 

Catalytic olefin metathesis, in only a few years, has risen to be one of the most important and reliable processes in organic synthesis. Recently, several reports by Schrock and Hoveydallsbbond forming transformations efficiently and enan-tioselectively. A recent concise and enantioselective synthesis of exo-brevicomin by Burke utilizes chiral catalyst 91 (Scheme 13) to effect the desymmetriza-tion of 90 through a ring-closing metathesis.11531... 

Since it is known that the tetranuclear mixed-valent platinum-blue complexes such as 19 and 57 undergo disproportionation and reduction by water as Eqs. (1)—(3) and (7)—(9) show (106, 113), all the species appearing in Eqs. (1)—(3) and (7)—(9) are present in the solution. However, only one or several of the four species in the solution may in fact be resposible for the catalytic olefin oxidation. To clarify this point, the effect of the Pt oxidation state in the platinum complexes was compared. The results are summarized in Table VII, which... 

I 11 Polymer-supported Olefin Metathesis Catalysts for Organic and Combinatorial Synthesis Tab. 11.6 Catalytic olefin metathesis with Ru complex (41). ... 

Kinetic analyses and deuterium-labeling experiments have demonstrated that, remarkably, the reductive elimination of TEA and the formation of intermediate C is the rate-determining step in the (de)hydrogenation cycle. Accordingly, hydrogenation of the acceptor appears to be slower than dehydrogenation of the alkane substrate. This contrasts with the fact that catalytic olefin hydrogenation is well-established in transition-metal-mediated chemistry [10]. 

In our refining and petrochemical industries we need to be more aware of catalytic olefin routes to propylene and ethylene. Several related capacity and cost increases impact this emerging route ... 

Catalytic Olefin Polymerization. Proceedings of the International Symposium on Recent Developments in Olefin Polymerization Catalysts, Tokyo, October 23-25,1989 edited by T. Kell and K. Soga... 

Vanadium precursors tend to promote addition polymerization of olefins on activation with aluminum co-catalysts. Nomura and coworkers recently reported the first example of catalytic olefin metathesis by a vanadium alkylidene complex.The well-defined, thermally stable V(v) alkylidene complex 7 effected ROMP of NBE at 80 °C. Cettain alkylvanadium complexes, including V(CH2Ph)2(=NAr )(OAr ) (Ar = 2,6-Pr 2C6H3 Ar = 2,6-Me2C6H3) and... 

Figure 14.5 Process flow chart for catalytic olefin cleavage to obtain 39.

R. Godoy Lopez, F. D Agosto, and C. Boisson, Synthesis of well-defined polymer architectures by successive catalytic olefin polymeriza-... 

With the advent of isotopic techniques, further knowledge concerning catalytic olefin epotidation become accessible. Itoginsku and... 

Olefinic compounds will often insert into carbon-transition metal bonds as CO does, and this reaction is an important step in many catalytic syntheses. When this step is combined with an oxidative addition of an organic halide to a palladium(O) complex in the presence of a base, a very useful, catalytic olefinic substitution reaction results (26-29). The oxidative addition produces an organopalladium(II) halide, which then adds 1,2 to the olefinic reactant (insertion reaction). The adduct is unstable if there are hydrogens beta to the palladium group and elimination of a hydridopalladium salt occurs, forming a substituted olefinic product. The hydridopalladium salt then reforms the... 

The homogeneous catalytic olefinic substitution, like the carboalkoxylation, does not generally proceed in high yield with aromatic chlorides under the usual conditions. A heterogeneous catalyst, palladium on charcoal, has been reported to cause chlorobenzene and other aromatic chlorides to react with styrene and styrene derivatives, with sodium carbonate as a base at 100° 30, 3]). In our laboratory, we have found the reactions occur as described, but the catalyst is apparently rapidly deactivated. 

To examine the possibility of a more efficient catalytic olefin metathesis, we prepared chiral Mo-based catalysts, 4a and 4b [10]. This approach was not without precedence related chiral Mo complexes were initially synthesized in 1993 and were used to promote polymer synthesis [6]. We judged that these biphen-based complexes would be able to initiate olefin metathesis with high levels of asymmetric induction due to their rigidity and steric attributes. Chiral complexes 4a and 4b are orange solids, stable indefinitely when kept under inert atmosphere. 

For select reviews on catalytic olefin metathesis, see Grubbs RH, Chang S (1998) Tetrahedron 54 4413 Furstner A (2000) Angew Chem Int Ed 39 3012... 

These results show that subtle changes in the nature of the metal carbene initiator or of the substrate can lead to important modifications in the relative energy levels of the three types of intermediates involved in catalytic olefin metathesis reactions. 

McKinney, R.J. (1985) Kinetic control in catalytic olefin isomerization. An explanation for the apparent contra-thermodynamic isomerization of 3-pentenenitrile. Organometallics, 4, 1142. 

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