1. Field of the Invention
This invention relates to the oxidation of organic compounds. In one aspect, the invention relates to the oxidation of compounds having at least one activated methylene radical while in another aspect, the invention relates to oxidizing such a compound in a multiphase system employing a catalyst comprising a synergistic combination of elemental carbon and a phase-transfer catalyst.
2. Description of the Prior Art
Hawthorne et al., "Base-Catalyzed Autoxidation of 9,10-dihydroanthracene and Related Compounds", Oxidation of Organic Compounds--I, Advances in Chemistry Series, 75, 14 (ACS 1968) teach the oxidation of 9,10-dihydroanthracene to anthraquinone by contacting the dihydroanthracene with oxygen and benzyltrimethylammonium hydroxide. Pyridine was used as a solvent.
Kang Yang, JOC, 42, 3754 (1977), teaches the oxidation of fluorene to fluorenone in the presence of charcoal and a base. The base is potassium t-butoxide in either a t-butyl alcohol or sodium hydroxide solution.
Alveri et al., "Autoxidation of Diarylene Methanes and Related Compounds in the Presence of Phase-Transfer Catalysts", Tetrahedron Letters, 24, 2117 (1977), teach the use of a phase-transfer catalyst, e.g., dicetyl diethylammonium chloride, in the autoxidation of diarylene methanes. Fluorene was converted to fluorenone in 100 percent yield after 24 hours at 30.degree. C. using the catalyst, oxygen and an aqueous sodium hydroxide/benzene biphasic reaction medium.
While all of the above teachings demonstrate utility, each suffers from one or more disadvantages. Principal among these disadvantages are undesirably slow reaction rates or the requirement of a neutralization step, the latter consuming starting reactants and generating a brine waste stream. Other disadvantages include the use of undesirable solvents, such as benzene, and the absence of catalyst and caustic recycle.