The Journey Begins:
Sir Nikola Tesla once said, “If you want to find the secrets of the universe, think in terms of energy,
frequency and vibration”. Chemistry is all fun and cool unless it blows into the domain of deadly toxins
and violently cataclysmic explosives. Ever wondered how TNT blows up with such insane detonation
velocity, or how Sir Alfred Nobel’s brother was brutally killed in a nitroglycerin explosion? Also, what
exactly caused the ruthlessness of atomic bombs behind the Hiroshima-Nagasaki incidents? The answer
is, my friend, blowing in the wind! Stay tuned with us, and tighten your seat-belts because we are about
to begin our rip-roaring journey to the center of explosives!
Breaking It Bad:
During the 19th century, the developing science of chemistry began to synthesize molecular species with
explosive properties. Scientists began to explore the kingdom of these high energetic materials which
included polynitropolycyclic cages, cyclic nitramines, NHN complexes. It was not more than the
next 20 years when various experimental and theoretical studies were encountered upon pyrolysis, heatresistivity and energetic binders. Explosives have eye capturing mechanisms all going on simultaneously that lead to their potential detonation. Energy density and structural stability are of key concerns that are needed to be taken into account while designing and synthesising energetic materials like certain molecular crystals and the cyclo-N5 complexes. From recent solvation studies, it has been found out that surprisingly a combination of intermolecular hydrogen bond tension and subsequent
compression leads massive energy storage in the bonds which may foster an explosion.
Now, some properties relevant to the detonation rate may be: (a) The structure of the compound
(structural stability due to some aromatic moiety can lower the detonation rate and lead to more stable
explosives like TATB, HMX), (b) The crystal structure provides can provide many opportunities for
the localisation of energy from outer physical stimuli, (c) The internal strain in a compound can trigger
the detonation of that compound and increase the rate of detonation. For instance, tetraazaisowurtzitane is highly strained explosive that is worth mentioning and also octanitrocubane
is a worthy member of the strained explosive family.
Fig. 01: Synthesis of the Devil: Octanitrocubane (Detonation Velocity: 10.2 km/s)
‘Bad Boys’ In Action:
The aggressive fam of explosives keeps a track of brisance, energy density, volatility, including their
sensitivity to initiation. However, the ‘big papas’ also swear to respect the oxygen balance (OB% or
Ω) for boosting up their rampant behaviour. A red-letter day caused a benchmark in explosive
chemistry when the Gurney equations set the floor on fire, holding up the underlying physics of
fragmenting versus non-fragmenting outer shells and respecting the conservation laws of momentum
and energy, presenting a vivid picturesque how energy is distributed between the metal shell and the
detonation gases. The chief classification is carried out on the basis of sensitivity. Primary explosives
such as benzoyl peroxide, halogen azides, tetrazene, hexamethylene triperoxide diamine
(HMTD) are terribly shock-sensitive and portrays their turbulence in blasting caps and percussion caps
to translate a physical shock signal. The two most common military primary explosives, lead azide and
lead styphnate shows off their versatility in large caliber munitions, mortars, artillery, warheads, etc.
Secondary explosives like TNT, RDX showing their usage in explosive trains as well as the tertiary ones
like the bulk industrial guy ANFO, consisting of fuel and oxidizer are typically gentler to handle than
the former ones. Octanitrocubane (ONC) is the big bro (Detonation velocity: 10.2 km/s) and its
synthesis requires rare chemicals, which in turn makes it even much more valuable than gold!
Beauty Within The Beast:
Explosives have both advantages and disadvantages but, in this occasion, we try to highlight mostly the
advantages and some of them can be: (a) Explosive welding: Joining of large sized components of
Fig. 02: RDX Explosion at US Junkyard: The Beast undresses!
metals that are difficult to weld are welded using explosive welding. In many critical components used in
space and nuclear applications, explosive welding is used to fabricate them as they cannot be made by
other processes. The inter-metallic bond are formed due to the high velocity oblique impact and this
impact helps in jetting action which helps in the joining of the metals having different metallurgical
properties. (b) Propellants: Many potential explosives are used as propellants. One such example is
ammonium nitrate which is now used as a major component in eco-friendly rocket propellant oxidizer
and other single and double base propellants like nitrocellulose, nitroglycerin, etc. Other composite
propellants can also be considered. (c) Medicinal applications: Whoa! Explosives as medicines!
Really?!! Well yes! Many explosive compounds have pretty cool medicinal properties. Nitroglycerin are
used as a vasodilator used to treat or prevent heart problems. Potassium nitrate is used as a medication
to cauterize small wounds. Really cool, right?!! Disadvantages include only the destruction of human
resource for the sole purpose of gaining power and these are the bad exploitations of chemistry and
science as a whole.
Fig. 03: Nitroglycerin sublingual tablets for the cure of Angina Pectoris
(AP) and Coronary Artery Disease (CAD)
The ‘Explosive Dilemma’ of Chaos:
Chemistry is fun indeed, and we can see it’s even triggered when catalyzed with the essence of
explosives! Well, it’s definitely imperative that the forensic scientists need to equip themselves with th
latest knowledge and cutting-edge research in the field of high energetic materials. Some of these
blasting explosives under research do not leave any residue. However advanced methods in synthetic
chemistry don’t fail to disappoint the deal. From regular household stuffs to synthetically prepared giant
heterocyclic rings, explosives are everywhere! Some wise men even stated that desire, like the atom, is
explosive with creative force. These high energy materials contain so many energetic stories in their life,
teaching us that strain, instability, even small thermodynamical fluctuations within the small molecules
can be triggered into this devastating violence of chaos! Isn’t that cool? Or rather, hot?