3 Synthetic Routes to Nitrate Esters
This chapter discusses the various synthetic methods available for the synthesis and incorpo-
ration of nitrate ester functionality into organic compounds. Nitrate esters are organic esters
of nitric acid and as such, their synthesis from the parent alcohol or polyol is fairly straightfor-
ward. However, the nitrate esters of many polyols are highly sensitive to mechanical stimuli
and so their synthesis, on both a laboratory and industrial scale, has to be treated as significantly
more dangerous than the synthesis of some other explosives. Many of the modern laboratory
methods for the preparation of nitrate esters focus on reducing this danger.
Low molecular weight nitrate esters, even those derived from polyols like glycerol, are
volatile and toxic. This toxicity originates from their biological activity as vasodilators and
has seen their extensive use in the treatment of angina pectoris. The use of nitrate esters in
organic synthesis is not extensive or particularly notable. However, the nitrate ester group is
an important ‘explosophore’ and this energetic group is found in numerous commercial and
military explosives, some of which are synthesized on an enormous scale.
3.1 Nitrate esters as explosives
Nitrate esters^1 are an important class of explosives for both commercial and military use.
Perhaps the most well known is glyceryl trinitrate (GTN) (1) which is commonly known as
nitroglycerine (NG). Nitroglycerine is produced commercially from the nitration of glycerol
with mixed acid. Pure nitroglycerine is a pale yellow oily liquid which freezes at temperatures
below 13◦C. In the pure state nitroglycerine shows an unacceptably high sensitivity to impact
and mechanical stimuli. The findings of Alfred Nobel, that nitroglycerine can be absorbed onto
porous materials, solved the problems associated with a liquid explosive of high sensitivity.
Nitroglycerine has been mixed with many absorbents and additives to give gelatinized explo-
sives like the many forms of dynamite, gelignite, blasting gelatin, and propellants like cordite
and ballistite. Nitroglycerine is one of the few explosives with a positive oxygen balance and
so it is often mixed with carbonaceous material or oxygen deficient explosives like nitrocel-
lulose. Despite nitroglycerine having many unfavourable properties synonymous with nitrate
esters, it is a powerful high explosive of high brisance (VOD∼7750 m/s atd=1.59 g/cm^3 ).
Nitroglycerine finds extensive use in gelatinized commercial explosives and as a component
of double-base (DB) gun and rocket propellants for military applications. Recently, the use
Organic Chemistry of Explosives J. P. Agrawal and R. D. Hodgson
©C2007 John Wiley & Sons, Ltd.
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