Organic Chemistry of Explosives

4 Synthetic Routes to AromaticC-Nitro Compounds

4.1 Introduction

The nitration of aromatic hydrocarbons is one of the most widely studied and well-documented

reactions in organic chemistry. Aromatic nitro compounds are of huge industrial importance in

the synthesis of pharmaceutical drugs, agrochemicals, polymers, solvents and perfumes, and

for the synthesis of other industrially important chemicals containing amine and isocyanate

functionality. However, early research into aromatic nitration was fuelled exclusively by their

use as explosives and intermediates in the synthesis of dyestuffs. The former is the subject of

this chapter.

While we believe our discussions of nitramine and nitrate ester synthesis to be comprehen-

sive, it would be quite impossible to have a comprehensive discussion of aromatic nitration

in this short chapter – published studies into aromatic nitration run into many tens of thou-

sands. The purpose of this chapter is primarily to discuss the methods used for the synthesis

of polynitroarylene explosives. Undoubtedly the most important and direct method for the

synthesis of polynitroarylenes involves direct electrophilic nitration of the parent aromatic

hydrocarbon. This work gives an overview of aromatic nitration but the discussion doesn’t

approach mechanistic studies in detail. Readers with more specialized interests in aromatic

nitration are advised to consult several important works published in this area which give

credit to this important reaction class.^1 –^12 The use of polynitroarylenes as explosives and their

detailed industrial synthesis has been expertly covered by Urba ́nski in Volumes 1 and 4 of

Chemistry and Technology of Explosives.^13

Nucleophilic aromatic substitution is a useful route to many functionalized polynitro-

arylenes whether the displacement is of a pre-existing nitro group or any other suitable

leaving group on the aromatic ring. For this reason nucleophilic substitution is discussed in

this chapter but only in the context of preparing polynitroarylene explosives (Section 4.8).

The ease of nucleophilic displacement of nitro groups in polynitroarylenes has implica-

tions for the suitability of some compounds as explosives and so this is also discussed

(Section 4.8.2).

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4 Synthetic Routes to AromaticC-Nitro Compounds