Preparation of dinitrobenzene

Deville [26] first prepared dinitrobenzene in 1841 by treating benzene with concentrated nitric acid and heating it to the boiling point. Soon after that Mus-Pratt and Hofmann [27] obtained it, using a mixture of nitric and sulphuric acid for the nitration. 

For a long time it was thought that a uniform substance was produced. However, m 1874 Rinne and Zincke [28], and also Komer [29] found that the o- and p- isomers are also formed along with large quantities of m- dinitrobenzene. 

The conditions for preparing dinitrobenzene were described more fully by Beil-stein and Kurbatov [29a] in 1875. They dissolved 1 part by volume of benzene in 2 parts by volume of nitric acid (sp. gr. 1.52). After cooling, 3.3 parts by volume, of sulphuric acid were added. 

The possibility that a certain quantity of trinitrobenzene may be formed, as an impurity in dinitrobenzene, was reported by Hepp [30] in 1882. 

Holleman and de Bruyn [31] investigated the influence of the nitration conditions on the quantity of isomers formed. When nitrating nitrobenzene with nitric acid or a nitrating mixture at temperatures below and above room temperature, they obtained the following percentages of isomers (Table 38). 

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Nitration in two stages in two nitrators. In industrial practice the preparation of dinitrobenzene is commonly carried out by nitration in two stages ... 

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