Biological oxidation, hydrocarbons

Katz, M., Chan, C., Tosine, H., Sakuma, T. (1979) Relative rates of photochemical and biological oxidation (in vitro) of polynuclear aromatic hydrocarbons. In Polynuclear Aromatic Hydrocarbons. Jones, P.W., Leher, P., Eds., pp. 171-189, Ann Arbor Science Publishers, Ann Arbor, MI. 

The Biocube aerobic biofilter is an ex situ off-gas filtration system that is commercially available. The technology utilizes microbes to biologically oxidize volatile organic compounds (VOCs) and complex odors. It can be used in conjunction with vapor-vacuum-extraction (VVE), a process that draws gases from subsurface soil. These gases often require further treatment before being released into the atmosphere. Biocube has been field tested and has been implemented at over 100 sites for the treatment of hydrocarbon vapors. The technology has also been successfully used for odor control at a variety of sites. In addition, the Biocube system can treat odor and VOC emissions simultaneously. The units are modular, so additional stacks can be added as needed for increased flow and/or removal rates. 

Relative Rates of Photochemical and Biological Oxidation (in vitro) of Polynuclear Aromatic Hydrocarbons," in POLYNUCLEAR AROMATIC HYDROCARBONS, P.W. Jones and P. Leber (Editors), Ann Arbor Science Publishers, Inc., Ann Arbor, MI, 171-89. 

Apart from potential industrial applications, homogeneous catalytic systems with metal-oxo intermediates have direct relevance to certain biological oxidation reactions. The biological reactions involve metalloenzymes such as Cyt P450, which has an iron-porphyrin complex in its active site. The enzyme catalyzes hydroxylation of a hydrocarbon by oxygen. This hydroxylation does not proceed through a radical-chain mechanism. There is sufficient evidence to indicate that a catalytic intermediate with an Fe=0 group is responsible for the hydroxylation reaction. 

The C—H bond can be activated by a metal complex, particularly when the complex plays the role of catalyst or photocatalyst. The reactions of hydrocarbons with metal complexes occur at low temperatures and can be selective. There are different pathways for C—H bond activation (i) by low-valence metal complexes, (ii) by high-valent metal-oxo compounds, (iii) by molecular oxygen and oxygen atom donors, (iv) by biological oxidation, or (v) by photocatalytic enhancement (21). 

The principal pathway by which unsubstituted and many substituted aromatic hydrocarbons are metabolized in mammals consists of the initial formation of arene oxides, which undergo a variety of enzymatic and nonenzymatic reactions prior to excretion of the resulting more polar, oxidized hydrocarbons via bile or urine. Taken together, these pathways represent an attempt on the part of the animal to detoxify or eliminate such nonpolar xenobiotic substances for which it has no apparent use. Although detoxification is the probable role of the arene oxide pathway, it is equally clear that chemically reactive species mediate this process. Thus, studies over the past several years have either implicated or established arene oxides in a causative role in such adverse biological reactions as cytotoxicity, mutagenesis, and carcinogenesis via covalent interaction of arene oxides with biopolymers,... 

Biological systems fermentation, oxidation of sludges, production of proteins from hydrocarbons, and biological oxidations. 

When we study and generalize the P-450 oxidations, three important issues stand out. (1) We need an inexpensive electron source for continuously activating the redox catalyst (2) we need a redox transition metal catalyst capable of forming the oxo species and (3) we need an electron mediator, usually selected from noble metals, capable of transferring electrons from its source to the redox catalyst. These three issues are critical in adopting biological oxidation chemistries to large-scale hydrocarbon autoxidations. 

This chapter is devoted to reactions of hydrocarbons and other C-H containing compounds with complexes of metals in a high oxidation state [I]. Section VIII. I describes reactions which lead to isolable or detectable organo-metaUic compounds. However, many known processes of hydrocarbon oxidation by high-valent metal complexes either do not involve a step of a-organyl derivative formation at all or the formation of such intermediates is only suspected. High-valent metal intermediates have been proposed to take part in certain biological oxidation processes (see Chapter XI). 

It is interesting to note that, provided the RH concentration is sufficient for RO radicals to disappear by the reaction with the hydrocarbon, the stoichiometry of the reaction under specified conditions corresponds to the ratio Sn(II) O2 ROH =1 1 1, which means that it will be the same as the stoichiometry of oxidation in the presence of monooxygenase. This shows that the stoichiometry of the process cannot be used as evidence for its mechanism. The example with Sn(II), treated here so extensively, is further evidence of the danger of drawing conclusions about the models of biological oxidation based merely on formal analogies. 

The current views about aerobic biological oxidation of alkanes and arenes involving various oxygenases. Its chemical simulations are discussed in this chapter, which gives only a brief survey of the most recent data for biological C-H activation and hydrocarbon oxidation. It is noteworthy that, somewhat unexpectedly, important and profound analogies exist between chemical activation by metal complexes and biological C-H oxidation. It is necessary to note that many books [14] and reviews [15] have been devoted to enzymatic oxidations and processes that more or less closely model these oxidations. 

Oxidation is one of the most important reactions in chemistry and biochemistry. Combustion of hydrocarbons drives much of our economy and transportation, and biological oxidation processes are fundamental to life and ecology. From an industrial viewpoint, oxidation reactions occupy a pivotal role in the conversion of hydrocarbons into required products, and indeed it has been estimated that over 50% of such processes involve hydrocarbon oxidations. ... 

Biological oxidation of the hydrocarbon adamantane by the fungus Absidia glauca gives a mixture of two alcohols. Classify the carbon in adamantane that is oxidized in forming the major product. 

Biological oxidation of hydrocarbons is a commonly observed process. 

---