Olefin oxygenation

Pidko, E.A. and van Santen, R.A. (2006). Confined space-controlled olefin-oxygen charge transfer in zeolites. J. Phys. Chem. B 110, 2963-2967... 

VII. Olefinic Oxygen, Sulphut and Selenium Complexes of Transition Metals... 

The first step in the peroxide-induced reaction is the decomposition of the peroxide to form a free radical. The oxygen-induced reaction may involve the intermediate formation of a peroxide or a free radical olefin-oxygen addition product. (In the case of thermal and photochemical reactions, the free radical may be formed by the opening up of the double bond or, more probably, by dissociation of a carbon-hydrogen bond in metal alkyl-induced reactions, decomposition of the metal alkyl yields alkyl radicals.)... 

Organometallic Chemistry of Rhodium and Iridium Directed towards Olefin Oxygenation... 

The olefin oxygenations carried out with dioxygen seem to be metal-centered processes, which thus require the coordination of both substrates to the metal. Consequently, complexes containing the framework M (peroxo)(olefin) represent key intermediates able to promote the desired C-0 bond formation, which is supposed to give 3-metalla -l,2-dioxolane compounds (Scheme 6) from a 1,3-dipolar cycloinsertion. This situation is quite different from that observed in similar reactions involving middle transition metals for which the direct interaction of the olefin and the oxygen coordinated to the metal, which is the concerted oxygen transfer mechanism proposed by Sharpless, seems to be a more reasonable pathway [64] without the need for prior olefin coordination. In principle, there are two ways to produce the M (peroxo)(olefin) species, shown in Scheme 6, both based on the easy switch between the M and M oxidation states for... 

Radical-chain processes that are usually operative in the auto-oxidation of free cod [73] can produce olefin oxygenation in some instances. This is the case of the reaction of [Ir(ri -CpO(cod)] (Cp = 3,5-(Me3Si)2Cp) [74] with dioxygen in tetrachloroethane (TCE) under reflux, where a free-radical chlorine-photosensitized oxidation gave two isomeric ketones (Eq. 18). 

Thiosemicarbazones, such as 331, and thiourea (333) give rise to sulfinic acids when subjected to photosensitized oxygenation reaction conditions.62,233 It was suggested that by analogy to olefin oxygenation the primary products may be of hydroperoxidic nature... 

Ethylene action depends on binding to a receptor site that has a low affinity for other olefines. Oxygen is required for the response, which is competitively inhibited by carbon dioxide. 

The abundance and low cost of light alkanes have generated in recent years considerable interest in their oxidative catalytic conversion to olefins, oxygenates and nitriles in the petroleum and petrochemical industries [1-4]. Rough estimates place the annual worth of products that have undergone a catalytic oxidation step at 20-40 billion worldwide [4]. Among these, the 14-electron selective oxidation of -butane to maleic anhydride (2,5-furandione) on vanadium-phosphorus-oxide (VPO) catalysts is one of the most fascinating and unique catalytic processes [4,5] ... 

The identification of a complex is not proof that the reaction path is by way of that particular complex, as a more unstable intermediate is likely to be involved. The reports that aluminum halides alone are not catalysts for n-butane unless a trace of olefin, oxygen, or water is present even when HX, the corresponding halogen acid, is present (Pines and Wachher, 128), lead one to suspect that both a nucleophilic and an electrophilic reagent are needed and that the role of the solvent in solvat-... 

Heterocycles as ligands in rhodium catalysts for olefin-oxygenation 04AG(E)4142. 

G. Yin, M. Buchalova, A. M. Danby, C. M. Perkins, D. Kitko, J. D. Carter, W. M. Scheper, D. H. Busch, Olefin oxygenation by the hydroperoxide adduct of a nonheme Manganese(lV) complex Epoxidations by a metallo-peracid produces gentle selective oxidations, /. Am. Chem. Soc. 127 (2005) 17170. 

The total rate of reaction and the selectivity to different products (olefins, oxygenates, carbon oxides) depend on relative efficiencies of different transformations of free radicals in the gas phase and in the heterogeneous steps, as well as on the transport phenomena. 

Fig. 6. Scheme of surface polymerization with straight chain and branched growth and 3 sorts of products (paraffins, olefins, oxygenates)... 

With cuprous oxide catalyst, product oxidation rates are quite high. This fact, combined with the need of maintaining the cuprous oxide state, leads to best results with a rather high olefin/oxygen ratio, for example, CgHg/O = 5. Then the conversion per pass of the olefin is about 10-20%, and selectivity to unsaturated aldehyde is often of the order of 60-85%. The reaction of propylene is... 

The oxidation of propylene and of the four butenes over bismuth molybdate is first order in olefin and independent of oxygen and products (131). For higher olefins, however, the rate drops off markedly with increasing conversion, and a positive oxygen dependence appears 132). The oxidation of 1-pentene was studied in detail by Adams (132) by feeding various mixtures of olefin, oxygen, and pentadiene to a flow reactor under conditions of low conversion (<10%). The rate of oxidation was found to fit the following expression ... 

Functionalization of Olefins. Oxygenation of olefins by molecular oxygen was performed in the presence of NaBfLj and metal catalysts such as Mn , 478 ( 11179 p m (eq42).i 0-i i... 

Studies on the mechanism of other olefin oxygenations, such as allylic oxidation, glycol formation and redox hydration can be expected in the near future. 

In 1989, Volz reported the isolation of an iodosylbenzene complex of [(TDCPP) MnCl] from the reaction of the components at —78°C (Scheme 9) [35]. The crystalline compound could epoxidize olefins, oxygenate cyclohexane, and oxidize triphenylphosphine. Interestingly, reaction of this material with ammonia led to the formation of the manganese(V) nitrido complex [(TDCPP)Mn=Nj. In 1992, Volz reported details for related CgFsIO complexes [36]. 

Table 6.3 Product ratios and 0 labeling data of the catalytic olefin oxygenation with bispidine-ferryl complexes (cyclooctene, MeCN, HjOj, TON" = 10) [7b, 35],...

Evidence for an unconcerted olefin oxygenation mechanism has been obtained by observing the sMMO-catalyzed oxygenation of some diagnostic olefins. The oxygenation of norbomadiene and quadricyclane catalyzed by sMMO fi om M capsulatus (Bath) gives the same product, bicyclo aldehyde, as shown in eq. (24 )[75]. 

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