Hydroxylation alkane

This problem was taken on by the Jerusalem group who used DFT (B3LYP) computations to model the mechanism of methane hydroxylation -101-103 allylic hydroxylation of propene - and 

Hata et a/. , used porphine macrocycle and CHjS as a proximal ligand, and arrived at basically the same conclusion, that the mechanism is typified by TSR. 

A simple TSR scheme leads to the following expression for the ratio of the real to the apparent lifetimes  

Calculations of Yoshizawa et a/. using CHjS as a proximal ligand retrieved the TSR scenario, and recently also the rebound barrier 

The hydrogen abstraction barriers in alkane hydroxylation shown in Table 2.1 exhibit a high sensitivity to the donor property of the alkane and the C-H bond energy. They range from 26.7, 

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Experimental procedures have been described in which the desired reactions have been carried out either by whole microbial cells or by enzymes (1—3). These involve carbohydrates (qv) (4,5) steroids (qv), sterols, and bile acids (6—11) nonsteroid cycHc compounds (12) ahcycHc and alkane hydroxylations (13—16) alkaloids (7,17,18) various pharmaceuticals (qv) (19—21), including antibiotics (19—24) and miscellaneous natural products (25—27). Reviews of the microbial oxidation of aUphatic and aromatic hydrocarbons (qv) (28), monoterpenes (29,30), pesticides (qv) (31,32), lignin (qv) (33,34), flavors and fragrances (35), and other organic molecules (8,12,36,37) have been pubflshed (see Enzyp applications, industrial Enzyt s in organic synthesis Elavors AND spices). 

In addition to nonheme iron complexes also heme systems are able to catalyze the oxidation of benzene. For example, porphyrin-like phthalocyanine structures were employed to benzene oxidation (see also alkane hydroxylation) [129], Mechanistic investigations of this t3 pe of reactions were carried out amongst others by Nam and coworkers resulting in similar conclusions like in the nonheme case [130], More recently, Sorokin reported a remarkable biological aromatic oxidation, which occurred via formation of benzene oxide and involves an NIH shift. Here, phenol is obtained with a TON of 11 at r.t. with 0.24 mol% of the catalyst. 

Suzuki M, T Hayakawa, JP Shaw, M Rekik, S Harayama (1991) Primary structure of xylene monooxygenase similarities to and differences from the alkane hydroxylation system. J Bacteriol 173 1690-1695. 

In Pseudomonas putida ppGl that carries the OCT plasmid, there is duplication of some of the loci. Those for alkane hydroxylation (alkA, alkB, and alkC) and for alkanol dehydrogenation (alcO) occur on the plasmid, whereas those for alcA and alcB, and for aldehyde dehydrogenation (aldA, aldB) occur in the chromosome (Grund et al. 1975). 

Funhoff EG, U Bauer, I Garcla-Rubio, B Witholt, JB van Beilen (2006) CYP153A6, a soluble P450 oxygenase catalyzing terminal-alkane hydroxylation. J Bacteriol 188 5220-5227. 

Fasan, R., Chen, M.M., Crook, N.C. et al. (2007) Engineered alkane-hydroxylating cytochrome P450 (BM3) exhibiting nativelike catalytic properties. Angewandte Chemie (International Edition in English), 46 (44), 8414-8418. 

As will be discussed further in Section 7.4.5, intermediates (5a), (5b), and (6) (Figure 7.14) are too reactive to build up during catalytic turnover. This has led to the assumption that intermediate (6), or compound I, is the active oxygen species responsible for alkane hydroxylation, alkene epoxidations. 

Figure 7.19 The Groves oxygen rebound mechanism for alkane hydroxylation.

Other examples of oxidant-iron(III) adducts as intermediates in iron porphyrin-catalyzed reactions have been published as listed in references 54a-k. Competitive alkene epoxidation experiments catalyzed by iron porphyrins with peroxy acids, RC(0)00F1, or idosylarenes as oxidants have been proposed to have various intermediates such as [(porphyrin)Fe (0-0-C(0)R] or [(porphyrin)Fe (0-I-Ar)]. Alkane hydroxylation experiments catalyzed by iron porphyrins with oxidant 3-chloroperoxybenzoic acid, m-CPBA, have been proposed to operate through the [(porphyrin)Fe (0-0-C(0)R] intermediate. J. P. CoUman and co-workers postulated multiple oxidizing species, [(TPFPP )Fe =0] and/or [(TPFPP)Fe (0-I-Ar)] in alkane hydroxylations carried out with various iodosylarenes in the presence of Fe(TPFPP)Cl, where TPFPP is the dianion of me50-tetrakis(pentafluorophenyl)porphyrin. ... 

It has been also found that PhIO as an oxidant in the presence of a catalytic amount of sulfonated manganese and iron porphyrin supported on poly(vinylpyridinium) polymers in olefin epoxidation and alkane hydroxylation is a better oxidant than Bu4NHS05 °. Oxidation of adamantane to 1-adamantanol in good yield using BU4NHSO5 and acetone in the presence of aqueous NaHCOs was also reported . ... 

Certain manganese porphyrins adsorbed on silica or alumina, or intercalated in different mineral matrices such as montmorillonite, are also very efficient in alkane hydroxylation.150 151 Alcohol yields and alcohol ketone ratios are remarkably higher than those obtained with the corresponding soluble manganese porphyrins. Manganese tetra(4-Al-methylpyridiniumyl)porphyrin supported on montmorillonite, for instance, is efficient in the hydroxylation of compounds of low reactivity such as n-pentane and n-heptane.151... 

D KIE associated with alkane hydroxylation by cytochromes P-450 and intermolec-ular D KIE in the alkane hydroxylations catalysed by manganese and iron porphyrin complexes... 

H Saturation mutagenesis of 9-10A Terminal alkane hydroxylation and epoxidation [137, 138]... 

A linear tetradentate ligand, bpmen [N,N -dimethyl-N,N -bis(2-pyridylmethyl)-l,2-diaminoethane] was reported to allow stereospecific alkane hydroxylation [36, 40], The same holds true for the [Fen(TPA)(CH3CN)2]2+ [TPA = tris(2-pyridylmethyl) amine] catalyst family (Figure 3.3) [35],... 

Among the oxidation catalyzed by heme enzymes, alkane hydroxylation is the hardest process to mimic with synthetic metalloporphyrins (7). This finding is also true for myoglobin mutants, even though the mutants are able to afford... 

For an overview of the scope of enzymatic alkane hydroxylation FI. L. Holland,... 

A. V Epoxidation and Alkane Hydroxylation Catalysts 1. Functionalized Polymers as Supports... 

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