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Abstract

Disclosed herein is a cost effective and environmentally friendly process to prepare 1-hydroxy-6-substituted pyridones from 2,6-dichloropyridine. The process includes the steps of (a) reacting 2,6-dichloropyridine with hydrogen peroxide in the presence of trifluoroacetic acid at a first temperature to produce a first intermediate containing (1) trifluoroacetic acid and (2) 2,6-dichloropyridine N-oxide and/or salts thereof; (b) adding sulfuric acid to the first intermediate to provide a second intermediate; (c) removing trifluoroacetic acid from the second intermediate to provide a composition containing 2,6-dichloropyridine N-oxide and/or salts thereof which is essentially free of trifluoroacetic acid; (d) reacting 2,6-dichloropyridine N-oxide and/or salts thereof from step (c) with RXH and a base wherein each R is independently a substituted or unsubstituted hydrocarbyl group having between 1 and 20 carbon atoms, X is oxygen or sulfur, to produce a corresponding 2,6-disubstituted-pyridine N-oxide; and (e) heating the disubstituted compound thereby producing the 1-hydroxy-6-substituted pyridone.

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First Claim