Hydrocarbon oxidation has long been a significant source of organic chemicals. Both vapor‐ and liquid‐phase reactions are of interest; they are believed to involve free‐radical chain mechanisms. Modern understanding of these reactions has developed over the last half of the twentieth century. Although sharp disputes are frequent, significant agreement on underlying principles is apparent.
Vapor‐phase oxidations can be conveniently divided into low, middle, and high temperature ranges. Fundamental changes in mechanisms occur over these regions. The direct oxidation of methane to methanol, formaldehyde, and/or C
2
products has received intense study, but no viable processes have yet been developed. Most other studies in this area are directed toward fuel utilization and pollution abatement.
Liquid‐phase oxidations of aliphatics have declined in importance as sources of bulk chemicals. However, the oxidation of butane to acetic acid, and of isobutane to
t
‐butylhydroperoxide (to produce propylene oxide), and of cyclohexane to cyclohexanol and cycohexanone (to produce adipic acid and nylon), remain important industrial processes. Oxidations of alkylaromatics continue to be important industrially. The oxidation of
p
‐xylene to terephthalic acid and cumene to phenol are dominant routes to these products. The potential for producing fine chemicals by such oxidations is developing rapidly.