Isoalkanes are branched hydrocarbons and are more resistant to enzymic degradation than are straight-chain hydrocarbons, and branched chains are more likely to be encountered, on a chance basis, with longer chain length or higher molecular weight. Unsaturated hydrocarbons are more amenable to degradation than saturates. The oxidation pathways of the isoalkanes have not been fully elaborated, although considerable work has been done. Humphrey (1967), however, made several generalizations: (1) straight-chain alkanes are more easily oxidized than brached chains, (2) compounds containing one methyl branch are attacked only when the molecule contains a sufficiently long unbranched chain, and (3) alkanes with a branched alkyl group larger than methyl or with multiple methyl branches are not oxidized. A few other generalizations with regard to branching have been summarized by McKenna and Kallio (1964) on the basis of microbial growth on hydrocarbon substrates. Addition of a second CH3 group into a saturated straight chain usually makes the molecule more recalcitrant to a variety of genera and species of organisms. That is, a quaternary carbon atom makes the compound more refractory to enzymes, particularly if it is adjacent to the terminal carbon atom.
KeywordsHydrocarbon Sewage Alkane Borate Dehydrogenation
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