The displacement of atoms and groups in the benzene nucleus

Preparation of the Dichlorotoluquinones

“…The position of the nitro group was assigned on the basis of the steamvolatility of the compound and its non-identity with 3,6-dichloro-4-nitro-ocresol. Such replacement of halogen by nitro has been observed previously (7). The 3,6-dichlorotoluquinone was finally obtained satisfactorily by the scheme outlined in formulas I-V.…”

Anomalous Nitration Reactions.

“…1.5204) is used at 0°C. the product is a mixture of 0-2-dinitrostyrene and ß-4-dinitrostyrene (84): The replacement of the carboxyl group by a nitro group during the nitration of phenolic acids has been noted by many investigators (17,23). In general, the carboxyl is more readily replaced when there are two or more hydroxyl groups or other ortho-para-directing groups on the nucleus, yet the nitration of 2,3,4trimethoxybenzoic acid yields only the normal nitration product.…”

“…With a mixture of sulfuric acid and 60 per cent nitric acid at 5~10°C. the normal nitration product, 3-nitro-4-dimethyIammobenzoic acid, is HNO,, H2SO, 3,5-Dinitroanisic acid; 2,4, ß-trinitroanisole (23) o-Nitrosalicylic acid HNO, (fuming) o-Dinitrophenol; dinitrosalicylic acid The ease with which the carboxyl group and a methyl group are displaced in p-dimethylaminobenzoic acid is illustrated by its reaction with sodium nitrite and hydrochloric acid. The principal products, formed in nearly equal amounts, are as follows ( 11 One methyl group in dimethylaniline is replaced by a nitro group when the amine is first dissolved in cold sulfuric acid and then nitrated with nitric acid at 40-55°C.…”