Reactivity in oxidations

Reactivities of several chlorinated solvents, including chloroform, with aluminum, iron, and 2inc in both dry and wet systems have been deterrnined, as have chemical reactivities in oxidation reactions and in reactions with amines (11). Unstabilized wet chloroform reacts completely with aluminum and attacks zinc at a rate of >250 //m/yr and iron at <250 //m/yr. The dry, uiiinhibited solvent attacks aluminum and zinc at a rate of 250 )J.m/yr and iron at 25 ]lni / yr. 

The presence of an alkenyl, phenyl, or alkynyl group one carbon away from a halogen, oxygen, or another electronegative atom, such as sulfur, makes allylic, benzyllic, and propargyllic electrophiles very reactive in oxidative addition... 

Kushch, S.D., Fursikov, P.V., Kuyunko, N.S., Kulikov, A.V. and Savchenko, V.I. (2001) Fullerene black relationship between catalytic activity in w-alkanes dehydrocyclization and reactivity in oxidation, bromination and hydrogenolysis. Eurasian Chemico-Technol. Journal, 3, No. 2, 131-139. 

The ethyl and butyl derivatives form comparatively stable binary complexes. The cocatalytic activity of these derivatives differs in different dehydrogenase systems (Table 4). Their reactivity in oxidized or reduced form with lactate,... 

The turnover-limiting step in this catalytic cycle depends on the steric and electronic properties of both the organohalide and the organometallic reagent as well as the nature of the main-group metal, and can also be affected by the structure of the metal catalyst. The order of halide reactivity in oxidative addition processes is I > Br = OTf > Cl, and as noted above, the relative rate of oxidative addition of various aromatic halides is roughly... 

Allyl carbonates are particularly useful allylic substrates. Thus, in addition to their high reactivity in oxidative addition, allyl carbonates have the advantage that the ally-lation reaction can be conducted under neutral conditions without an added base. The (7t-allyl)palladium intermediate (17) derived from an allylic carbonate has a carbonate anion that serves as a masked base to generate carbon nucleophiles (eq (112)) [143]. 

A comparison of olefin reactivities in oxidation over bismuth molybdate at 460° to those observed in aUyl hydrogen abstraction in solution at 65° by methyl radicals (140) is shown in Fig. 4. Considering the differences in phase and temperature, the correlation is quite good. The triangular points that are significantly off the line are for cis-and trons-2-butenes. An equally good correlation line was also obtained for comparison of oxidation with abstraction by fert-butoxy (141), again with the exception of three internal olefins, which seem to have abnormally low reactivity in the catalytic oxidation. 

Aldehyde CH bonds are reactive in oxidative addition, so it is not unexpected to find that aldehydes readily undergo catalytic reactions involving this oxidative addition. Several catalysts decarbonylate aldehydes as a result of the acyl hydride formed after the C-H addition undergoing deinsertion of CO, followed by reductive elimination of the alkane product (Eq. 2.49). The hard step in the process is the thermally induced dissociation of the resulting tightly bound CO. One such catalyst is [Rh(triphos)Cl] (triphos = PhP(CH2CH2PPh2)2) [134]. 

The cyclometalated Ru species generated electrochemically are very reactive in oxidation of reduced flavin adenine dinucleotide of GO. The excellent coupling between GO reduced by D-glucose and the Ru species is illustrated by the rate constant for the complex [Ru(phpy)(Me2phen)2]PF6, which equals 1.8x10 M s at pH 6.7 and 25 °C. There are no complexes of higher reactivity in Table VII Other cycloruthenated complexes are very reactive as well (Table IX). Variation of the nature of cycloruthenated and diimine... 

Bifunctional catalysts 142 and 143 can be used for environmentally benign oxidation of alcohols or alkylarenes at the benzylic position (Scheme 5.44) [114], These reactions, using Oxone as stoichiometric oxidant, afford the corresponding carbonyl compounds (or carboxylic acids in the oxidations of benzyl alcohol or toluene) in high yields under mild conditions and convenient work-up. Both catalysts 142 and 143 show similar catalytic activity in the oxidation of alcohols, while catalyst 143 has noticeably higher catalytic reactivity in oxidation at the benzylic position. Furthermore, these Si02-supported bifunctional catalysts can be recovered by simple filtration and directly reused [114],... 

Although probably restricted to electrophiles RX, which are extremely reactive in oxidative addition (R = alkyl or benzyl), this mechanism shows how the coupling product may be formed via a tra i-RPdNuL2 complex by bypassing the endergonic formation of the di -RPdNuL2. 

The results of molecular-weight measurements on a freshly prepared solution in benzene sug t a dimeric structure (found M = 88 calcd., M = 89S). In the solid state, [IrCI(C Hi4)2]2 decomposes slowly under the influence of atmospheric moisture. The compound is moderately soluble in benzene, chlorofoim, and carbon tetradiloride, but in general, these solutions are unstable for long periods of time. In comparison with the corresponding rhodium complex, this compound is more reactive in oxidative addition reactions. This u demonstrated by tte formation of iridium hydrides during reaction with hydrogen and hydrogen chloride, respectively. 

Amatore, C., Carr6, E., Jutand, A. et al. (1995) Rate and mechanism of the formation of zerovalent palladium complexes from mixtures of Pd(OAc)2 and tertiary phosphines and their reactivity in oxidative additions. Organometallics, 14, 1818-26. 

Amatore, C., Jutand, A., Lemaitre, F. et al. (2004) Formation of anionic paUadium(O) complexes ligated by the trifluoroacetate ion and their reactivity in oxidative addition. J. Organomet. Chem., 689, 3728-34. 

The basicity has been proposed to be one of the fundamental criteria for a good reactivity in oxidative methane coupling (16, 17). Two methods have recently been described (3, 5, 18) for basicity measurements. One is through benzoic add (Bronsted basidty), the other one through the adsorption and the desorption (TPD) of CO2 (Lewis basidty). The last one has been used by sending CO2 pulses on the surface at 20°C followed by TPD (see experimental). The amount of CO2 adsorbed at 20°C on the ASnOs (1) and (II) perovskites are given Table 4. 

Rhodium.—[Rh(CN>4] exhibits exceptionally high reactivity in oxidative addition reactions with alkyl halides (RX) which follow second-order kinetics according to the rate law... 

Mayo FR. Relative reactivities in oxidations of polypropylene and polypropylene models. Macromolecules 1978 11 942-6. 

The initial oxidation step has taken place at C-4 or at the double bond in the side chain at C-4. It has indeed been proved that both sites may be equally reactive in oxidative conditions (87). On the other hand, a concerted reaction via previous formation of an oxygen-substrate complex may be feasible. The oxidation pathways are presented in Fig. 106. 

According to the reactivity in oxidative dehydrogenation, the alcohols studied can be arranged in the following raw octan-2-ol > ethanol > propanol > butanol. The results obtained show the ways for the further development of multi-component catalysts prepared on the basis of hydrotalcite-like LDHs and their apphcation in oxidative transformations of EB, light alkanes and alcohols. 

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