Nitrate esters as explosives 89The main aim of synthesis and characterization of these nitrate esters was to explore their use
as additives to nitroglycerine to lower its freezing point and also, at the same time, to reduce
the impact and friction sensitivities of nitroglycerine resulting in its safer handling. Many
liquid nitrate esters are excellent energetic plasticizers. Triethylene glycol dinitrate (TEGDN)
(6) and 1,2,4-butanetriol trinitrate (BTTN) (7) are currently being investigated in the UK, the
USA and France as alternatives to nitroglycerine in propellant and explosive formulations.^2
1,2-Propanediol dinitrate (PDDN) (8) has found practical use as a high-energy monopropellant
for marine applications i.e. torpedoes.^1 ,^3
Erythritol tetranitrate (9), the product from theO-nitration of erythritol, is an explosive equal
in power to nitroglycerine and is a solid. Unfortunately, erythritol is not a commercially avail-
able chemical, the main source being from some species of seaweed. Consequently, erythritol
tetranitrate has never found use as a practical explosive.
OO O 2 NO O
O 2 NOONO 2ONO 2ONO 2
ONO 2n
10
nitrocellulose (NC)Figure 3.3Nitrocellulose (10), the product from nitrating cellulose in its various forms, is of vast
importance in the explosives industry as the main component of many modern gun and rocket
propellants, and as a binder for explosive compositions. Each monosaccharide unit of cellulose
contains three hydroxy groups available forO-nitration. The trinitrate corresponds to the fully
nitrated product containing 14.14 % nitrogen, but this degree of nitration is difficult to attain.
There are many types of nitrocellulose, all with different nitrogen content, which in turn,
affects physical properties such as solubility in organic solvents and affinity for water. Two
main grades of nitrocellulose are used in the explosives industry. Nitrocellulose of 12.2 %
nitrogen is commonly used in gelatinized explosives like the gelatine dynamites, whereas the
product containing 13.45 % nitrogen (guncotton) finds wide use in double-base propellants.
The extensive use of nitrocellulose in explosive technologies arises from the wide availability
of the raw materials, namely, mixed acid and cellulose, and the fact that nitrocellulose dissolves
in some solvents and liquid explosives to form gels – it is essentially the first energetic binder
to have been synthesized.
Nitrate esters are amongst the most powerful explosives known. However, their use for
some applications is limited. Like most esters they are readily hydrolyzed in the presence of
acid or base. Nitrate esters will gradually release nitric acid on prolonged exposure to water or
moisture, leading to an auto-catalyzed decomposition, and thus preventing long-term storage.
Nitrate esters are generally much more sensitive to mechanical stimuli and shock compared to
theirC-nitro andN-nitro counterparts.
Urba ́nski^1 has given a comprehensive account of the use of nitrate esters as commercial
and military explosives and their detailed industrial synthesis in Volumes 2 and 4 ofChemistry
and Technology of Explosives.