Tropones. Part II. The nitration of 2-chlorotropone: a new rearrangement

Abstract

When treated with nitric acid in acetic acid 2-chlorotropone gave 2-chloro-7-nitrotropone as the major product. In addition, 2-chloro-4,6-dinitrophenol and two m-hydroxybenzaldehydes were obtained together with picric acid and 2,5-dinitrobenzoic acid. Nitration of 2-chlorotropone with dinitrogen tetroxide gave 2-chloro-7-nitro- and 2-chloro-4,7-dinitro-tropone and 2-chloro-3-hydroxy-4-nitrobenzaldehyde. Rearrangement of 2-chloro-4,7-dinitrotropone with sodium hydroxide gives a mixture of 2-chloro-4-nitro and 2,5-dinitro-benzoic acid, with sodium carbonate 2-chloro-4,6-dinitrophenol, and with aqueous acetic acid a mixture of the phenol and 4-chloro-3-hydroxy-2,6-dinitrobenzaldehyde as the sole tetrasubstituted benzaldhyde. In the light of these and other facts the course of nitration is discussed. The formation of the m-hydroxybenzaldehydes constitutes a new rearrangement.