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Title: ORGANIC SYNTHESIS IN SUBCRITICAL WATER: OXIDATION OF ALKYL AROMATICS

Author
item Holliday, Russell
item JONG, BENTON - CLEMSON UNIV, CLEMSON, SC
item KOLIS, JOSEPH - CLEMSON UNIV, CLEMSON, SC

Submitted to: Journal of Supercritical Fluids
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/9/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Currently, hazardous solvents are used in many industrial processes. These hazardous solvents can be toxic, flammable, or carcinogenic. In an effort to find an alternative or replacement for use of hazardous solvents, we tested water under various conditions. We found that when water is reacted and/or treated by high temperatures and pressure, it's able to work as a replacement solvent. This information will be useful to a variety of industries that are seeking an environmentally friendly alternative.

Technical Abstract: The ability of sub- and supercritical water to solubilize both functionalized aromatic compounds and molecular oxygen was exploited for its use as a solvent to perform oxidative modification of a number of compounds. Alkyl aromatic compounds were oxidized to aldehydes, ketones and acids by molecular oxygen mediated by transition metal catalysts in subcritical water. A number of alkyl aromatics were oxidized directly to their acids, including p-xylene, o-xylene, m-xylene, ethylbenzene, and toluene. Alternatively, conditions were discovered which allowed the oxidation reactions to stop at the aldehyde stage. In addition, several aromatic methylenes could be oxidized to ketones, and anthracene could be oxidized to anthraquinone under the same conditions. The syntheses were performed in 10 mL stainless steel and Hastelloy-C batch reactors at 375 deg C with up to five equivalents of O2. The reactions were found to be very sensitive to the nature of the catalysts, with MnBr2 and CoBr2 providing the cleanest reactions and highest yields. Other metal salts led to severe charring or coupling reactions.