Rhone-poulenc Chimie

Laurent Bernard

Pascal Metivier

Picric acid, namely, 2,4,6-trinitrophenol, is readily and effectively prepared by nitrating o-nitrophenol and/or p-nitrophenol into at least one dinitrophenol in a nitric acid medium of reaction, characteristically essentially consisting of nitric acid or immixture thereof with a strong co-acid, the at least one dinitrophenol remaining soluble in the medium of reaction, and therein completing nitration of the at least one dinitrophenol and precipitating picric acid therefrom.

Preparation of picric acid

p-Nitrophenolic compounds, e.g., p-nitrophenol itself, are selectively prepared by (a) reacting a phenolic compound with a nitrosating agent in the presence of sulfuric acid, the concentration of which H.sub.2 SO.sub.4 being at least 60%, (b) oxidizing the p-nitrosophenolic compound thus formed with nitric acid, the concentration of sulfuric acid in the medium of reaction, upon completion of oxidation, being no greater than 80%, and (c) separating the p-nitrophenolic compound which thus precipitates.

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Venissieux, France

Laurent Bernard