This slide explains the forensic chemistry understanding of explosives

1. Forensic Chemistry
Unit 4

2. Explosives
 Explosives are substances that undergo a rapid oxidation reaction with the production
of large quantities of gasses.
 Due to this sudden buildup of gas pressure, the explosion occurs.
 The speed at which the explosive substance decomposes to permit this burst, enables
classification of explosives into high or low explosives.
 The most common explosive known is the low-explosive category.
 We use it in our crackers and pyrotechniques (fireworks etc.).
 Usual composition of common low explosive is a mixture of potassium or sodium
nitrate, charcoal and sulphur.
 High explosives are usually military grade explosives, to cause severe damage. They
depend on the heat, shock and friction effect.
 Examples include TNT, PETN, RDX etc.

3. Explosives
 The decomposition which causes the oxidation and buildup of gasses is known as
deflagaration (burning) in low explosives.
 In the case of high explosives, it is known as detonation. Detonation refers to the
supersonic shock wave that happens inside the explsoive body.

4. Explosives

5. Explosives
 There are crude bombs – made without much sophistication and blows up quite
uncontrollably.
 Country bombs – a little more sophisticated than crude bombs.
 There are military grade bombs – highly sophisticated, have serial numbering,
have more purer forms of explosive substances.
 IEDs – Making a crude bomb more dangerous.

6. Explosives
 Forensic?

7. MOTIVE
OPPORTUNITY
AND MOTIVE
MEANS,
OPPORTUNITY
,MOTIVE

8. Explosives – Legal definition
 Indian Explosives Act 1884, says explosive means gunpowder, nitroglycerine, nitro-glycol, gun cotton di-nitro-toluene,
tri-nitro-toluene picric acid, di-nitro-phenol, tri-nitro-resorcinol (styphnic acid), cyclo-trimethylene tri-nitramine, penta-
erythritol-tetranitrate, totryl, nitro gannidine, lead azide, lead styphynate, fulminate of mercury or any other metal diazo-
di-nitro-phenol, coloured fires or any other substance whether a single chemical compound or a mixture of substances,
whether solid or liquid or gaseous used or manufactured with a view to produce a practical effect by explosion or
pyrotechnic effect; and includes fog signals, fireworks, fuses, rockets, percussion-caps, detonators, cartridges,
ammunition of all description and every adaptation of preparation of an explosive as defined.
 The Explosive Substances Act 1908 defines Explosives as any materials for making any explosive substance; also
any apparatus, machine, implement or material used, or intended to be used, or adapted for causing, or aiding in
causing, any explosion in or with any explosive substance; also any part of any such apparatus, machine or implement

9. Explosive - Design
A basic Explosive consists of: Safety fuse, detonating cord, primer & detonator.
 The best explosive to study is the grenade. [simple design]
 Grenades contain:
 A body that contains the filler
 A filler, the chemical or explosive for fragmentation
 A fuse that ignites or detonates the grenade

10. Explosives
 Pyrotechnics is the science of using materials capable of undergoing self-
contained and self-sustained exothermic chemical reactions for the production of
heat, light, gas, smoke and/or sound.
 Pyrotechnic devices combine high reliability with very compact and efficient energy
storage, in the form chemical energy which is converted to expanding hot gases
either through deflagration or detonation.
 The fireworks used in games and shows are examples of pyrotechnics.

11. Classification
Based on Heat
Deflagerating
Detonating
Based on
sensitivity
Primary
Secondary
Tertiary
Based on
Velocity
Low
Explosive
High
Explosive
Based on
Composition
Primary
composition
Physical form
Based on
Use/Abuse
Military
Terrorism
IED

12. Standard Explosives
 Body
 Filler
 Fuse

13. Improvised Explosives
 Explosive (Filler)
 Initiating system (Fuse)
 Container (Body)

14. INITIATING SYSTEM
Three basic methods of initiating a device:
 Time delay- has a mechanical, chemical or electrical timing system explosion after
designated time has elapsed
 Victim operated- called a “booby trap-”Designed to function when victim triggers
the operating system. e.g. letter bomb
 Controlled by bomber- remote control

15. CONTAINER
Range from pipes, stereos, parcels and suitcases.
In case of low explosives provide for space for explosion
while in other provide for transportation, disguise and
fragmentation.
All provide useful info - suitcase would identify culprit
carrying it prior to blast by eyewitness.
A container might provide FP, addresses, marks , DNA.

16. Fillers
 Fillers are the actual exploding substance.
 They can deflagarate / detonate – depending on which they are classified as either
low / high explosive.
 Deflagaration is the action of heating a substance until it burns away rapidly.
 Detonation is the combustion of a substance which is initiated suddenly and
propagates extremely rapidly, giving rise to a shock wave.

17. Fillers
 Fillers are usually understood as either low / high.
 The next common classification is to differentiate them as either primary /
secondary explosives.
 A low explosive is usually made of a mixture of fuels and oxidizing agents. They
need heat / some other initiating system to make them blow off.
 A high explosive is one which explodes because they are made of chemicals which
easily oxidise themselves. All they need is a chemical / setup to initiate the
process.

18. Fillers
 Primary explosives are those which have very little tolerance level and can go off
on their own if not handled in a stable way. These are used in percussion caps on
firearms and also as part of fuse / initiating systems in explosives.
 Secondary explosives are those which will not detonate until proper initiation. They
are used as the main charge / filler in both bullets and explosives.

19. Fillers
 The most common low explosives is gun powder. It is made of a mixture of
potassium nitrate, charcoal and Sulphur in the ratio 75:15:10.
 We see this in GSR commonly.

20. Fillers
 Other low explosives include cordite, nitro-cellulose, nitro-glycerin and gun cotton.
 All the above mentioned low explosives are based on nitro-cellulose with varying
quantities of nitrogen in them.

21. Fillers
 High explosives of interest are as
follows
 TNT
 RDX
 PETN
 HMX
 Lead Azide
 Lead Styphnate
 DDNP
 Mercury Fulminate
 Silver fulminate
 Dynamite
 TATP
 ANFO

22. Effects of explosion
 Pressure effect
 Fragmentation effect
 Incendiary / Thermal effect
 Shock effect

23. Pressure effect
 The wave of pressure created by an explosive is known as ‘blast pressure wave’.
 The wave exerts 2 pressures – positive / pressure phase and negative / suction
phase.
 When an explosive bursts, it first pushes out due to accumulation of gasses. But
soon because of the sudden and severe emission of pressure, there is a vacuum
that is formed which sucks up the entire vicinity in a sudden sweep.

24. Fragmentation effect
 Usually a SED is made in such a way that when a explosion occurs, it causes the
body of the explosion to expand one and half times its original volume.
 When it finally ruptures, it breaks into fragments which are dissipated in the
immediate vicinity first, and if the pressure is sufficient, it may fragment itself and
get thrown to a far away spot as well.
 The velocity of these fragments can go up to 2500 feet / second.

25. Heat effect
 Heat is generated when hot gasses are released with a high velocity.
 High explosives produce greater heat than low explosives.
 This is dry heat. So scalds are formed on bodies.
 Plastic is melted. Metals are usually not affected.
 The heat can generate a bright flash / firewall or mushroom visual effect.

26. Shock effect
 The compression and suction phases of blast dynamics manifest as shock waves
and displacement waves respectively.
 The effects of a shock wave depends on the explosive charge, the distance from
the explosion and the terrain and surroundings.
 The effects include spalling on hard surfaces, hearing loss, mental shock etc.

27. Fillers
 High explosives of interest are as
follows
 TNT
 RDX
 PETN
 HMX
 Lead Azide
 Lead Styphnate
 DDNP
 Mercury Fulminate
 Silver fulminate
 Dynamite
 TATP
 ANFO

28. TNT - Trinitrotoluene
 Molecular formula - C6H2(NO2)3CH3
 Physical form - Solid has a pale yellow color
 Invented in 1863, is a common explosive.
 It is a synthesized chemical and requires mono-nitro toluene to synthesize.
 Commonly used in industry & military sector. Uncommon in IED's and country
bombs.

29. RDX - Research Department eXplosive or
Royal Demolition eXplosive
 C3H6N6O6 - Cyclo, tri, methylene, tri, nitramine.
 Patented in 1898, used widely in 2nd world war by the UK.
 US had a secret development programme post - world war. Produced large scale
RDX.
 RDX are solid crystals, white in color - insoluble in water and organic solvents.

30. PETN - PentaErythritol TetraNitrate
 C5H8N4O12
 It is a synthesized chemical - Pentaerythritol with nitric acid.
 Invented in 1894, used by Germans in world war II.
 It interestingly has a medical use - used to treat many heart ailments (Lentonitrat).
 White amorphous substance - does not dissolve in water or organic solvents.

31. HMX - High Melting Explosive, Her Majesty's
Explosive, High-velocity Military Explosive, or
High-Molecular-weight RDX
 C4H8N8O8 - Octogen.
 Powerful nitroamine high explosive; seen as white crystals
 The most complicated explosive to prepare.Used in missiles, rockets and other millitary
grade weaponry.
 Highly toxic and causes environmental pollution.Human toxicity has also been reported.

32. Lead Azide
 Pb(N3)2
 It is a highly unstable explosive; Usually seen in primers.
 Stored in rubber, it is less active.
 It is synthesized using sodium azide and lead nitrate.
 Invented in 1891, used during Vietnam war. US was blamed of stockpiling and later
ceased use completely in 1990.
 Its detonation velocity is more than 5km/sec.
 Lead azide wa sused during the assasination attempt on former US president Ronald
Reagen.

33. Lead Styphnate
 C6HN3O8Pb - Derived from styphnic acid.
 Usually used as primer - highly sensitive.
 Color is highly variable - yellow, gold, orange, reddish brown etc.
 Invente din 1874 - used as primers in many high explosives and ammunitions.

34. DDNP - Diazodinitrophenol
 C6H2N4O5
 Usually seen as dark yellow to dark brown crystals.
 Used to make dyes and explosives - slightly low in explosion nature.
 Can be de-sensitized in water or Sodium hydroxide.
 Prepared first in 1858 - still used to make explosives due to the ease in ability to control
and transport.

35. Mercury Fulminate
 C2N2O2Hg
 Highly sensitive to friction; Used as primers and triggers.
 Percussion caps are usually made using mercury fulminate.
 Invented in 1820 - was considered a dream find.
 Used in mock bombs - in film shooting
 Brown amorphous powder

36. Silver Fulminate
 AgCNO3
 It is also used as a primer. It is highly sensitive as the weight is more.
 Even a single water droplet's friction can make it go off.
 Invented in 1800. Used as detonator.

37. Dyanamite
 (O 2 N 2 CH 2) 3
 Invented by Alfred Nobel in 1867.
 Nitro-glycerin based compound
 Still considered a good explosive

38. TATP - Triacetone Triperoxide
 Quite a recently found explosive
 Used as a detonator in 2001
 Highly stable and also powerful at the same time.
 Usage is increasing in the recent past.

39. ANFO - Ammonium Nitrate Fuel Oil
 It is highly used as a industrial explosive.
 In coal mining, quarrying etc.
 So it is commercially available.
 Highly powerful. But also partially unstable.

40. Homemade explosives
 As explosives are formed of any substance which can rapidly oxidise producing excess
amounts of gasses, and literally many household objects can fall into the above
category, home-made explosives are a possibility with little or no experience in making
them.
 In fact the major source of explosive material to the bomb makers come from a house
hold business which involves making fire crackers. Fire crackers in India are usually
made as a house-hold business and the proceeds from making them help many families
thrive in society.

41. Homemade explosives
 The firecrackers and pyrotechnics use common black powder – which is majorly
constituted of potassium nitrate and also contains Sulphur and Carbon powders.
Potassium Nitrate is controlled commodity and is available with a license to house-holds
manufacturing firecrackers.
 Firecrackers are easily available in India and are used to mark a celebratory event. They
are legal, and anyone 18 and over can buy them without a license. Diwali fireworks are a
family event in many parts of India. People light up fireworks near their homes and in
streets. Additionally, cities and communities have community fireworks. This custom may
have begun on the Indian subcontinent after 1400 CE when gunpowder started being
utilised in Indian warfare.
 India's first fireworks factory was established in Calcutta during the 19th century. After
Indian independence, Sivakasi in Tamil Nadu has emerged as India's fireworks hub.

42. Homemade explosives
 The debate over fireworks causing air pollution has brought about the concept of green
crackers in India. But still the use of potassium nitrate happens uncontrolled in India.
 Licensed firecrackers units throw away much of the potassium nitrate that is purchased
during the manufacture. They also are the sources for black market selling of potassium
nitrate.

43. Homemade explosives
 Fire cracker industry makes use of the fillers that they obtain from licensed sources and
manufacture firecrackers in their units.
 The Chinese started this habit of homemade explosives as an industry. The firecracker
industry actually provided a fair amount of jobs for the locals, including entire families who
would work in various stages of the making–tube-rolling, wrapping, sealing, clamping,
braiding, packaging, printing, and packing were all done by local Chinese.

44. Homemade explosives
 The filler is mixed to make colloids, later rolled into tubes or different shapes of the
desired explosives. Once rolled they are wrapped with cardboard wads to give them a
‘close to air tight’ space. Post wrapping, they will be sealed at both ends using metal
alloys in the form of cups, clamped to make them stand tight. Then the fuse will be
braided on top of the tube explosives. The final product is packaged, printed with
trademarks and finally batched and packed as multiple units in one box and shipped.
 During the above process, there are many accidents which are reported. This causes loss
of lives and property. The effect of these accidents are similar to what we will find in actual
explosive scenes.

45. Homemade explosives
 The homemade explosives are made similar to what happens in a fire cracker industry.
Bomb makers with little or no knowledge get access to these filler chemicals and start
experimenting. Resources available on the internet, training received from other bomb
makers inspire these anti-social elements to create homemade explosives.
 These homemade explosives may not possess the industrial know-how of fire crackers.
They usually are crude in nature. The fuse may not be similar to fire crackers. Usually
they are made in such a way that they are tied tightly and packed. The fuse mechanism is
to use friction or pressure by throwing the explosive to make it go off.
 The fillers will be mixed with shrapnel’s and other sharp objects to increase their effect in
causing more damage. IED’s are commonly noticed in homemade explosives. The crude
nature of these homemade explosives make them more prone to being fashioned into an
IED.

46. Military explosives
 Military explosives can also be called Standard Explosive Devices (SEDs) and are made
using standardized procedures using standard chemicals in their standard quantities.
They are designed by the military to create damage to the enemy lines.
 The SEDs are made in different categories – to damage mechanical structures, to take
lives or to produce a shock wave. Depending on the need, different explosive substances
are used in the manufacture and the fillers and fuses are made suitable for the need.
 SEDs are standardized in their specifications and therefore are serial numbered to be
able to trace back to manufacturer, serial number, batch number etc. They also possess
trademarks of the production unit.
 In India, the Defense Research and Development Organization (DRDO) is mandated with
the manufacture of SEDs for military use.

47. Military explosives
 SEDs can be understood as having a filler, fuse and a container.
 Container in a SED is usually made of standardized material and serves to enclose,
control, and suppress the explosive blast forces, biologically and/or chemically hazardous
agents, and fireball resulting from detonation of an explosive device. This is an essential
difference from IEDs which are made in such a way to not control / suppress the ill effects
of a bomb.
 Fuses in a SED is also made of standardized means. Fuse is meant to light the filler and
therefore must be able to catch fire easily. Therefore, the use of primers is suggested for
fuses. But that can also make the explosive highly unstable and therefore not preferred.
Modern day safety fuses are often used in mining and military operations, to provide a
time-delay before ignition, and they more often than not are used to initiate an explosive
detonator, thereby starting an explosive chain reaction to detonate a larger more stable
main charge. This is known as a safety fuse. It basically uses a primer but has a safety
mechanism to keep the explosive in control.

48. Military explosives
 The fillers used in SEDs are high explosives. The commonly seen high explosives are as
follows:
 TNT
 RDX
 PETN
 HMX
 Lead Azide
 Lead Styphnate
 DDNP
 Mercury Fulminate
 Silver fulminate
 Dynamite
 TATP
 ANFO

49. Blasting Agents
 Blasting agent is any material or mixture, consisting of a fuel and oxidizer, intended for
blasting, not otherwise classified as an explosive and in which none of the ingredients are
classified as an explosive, provided that the finished product, as mixed and packaged for
use or shipment, cannot be detonated by means of a blasting cap when unconfined.
 Basically blasting agents are explosives which require a primer to make them go off. They
are highly stable explosives and won’t go off by friction or cap striking (percussion cap
striking as in firearms). They require a primer (a substance which can easily catch fire) to
make them go off. Explosives are cap-sensitive, whereas blasting agents are not and
therefore require a primer.

50. Blasting Agents
 The many industrial and military uses for explosives and blasting agents—ranging from
earth moving to seismic wave generation to materials modification to munitions to
propulsion—have generated a host of sophisticated and specialized explosives products
and delivery packages. However, in terms of overall revenues, markets, and products, the
business is overwhelmingly dominated by chemical materials based on the intermediate
production of nitric acid (principally ammonium nitrate [AN]) that are used by the world’s
mining and quarrying industries.
 Ammonium nitrate consumption for explosives has grown because of its safety advantage
over other products such as dynamite. Ammonium nitrate can be shipped and stored and
mixed with fuel oil when needed. Ammonium nitrate fuel oil (ANFO) is made of about 94%
ammonium nitrate and 6% fuel oil. ANFO is widely used as an explosive in mining,
quarrying, and tunneling construction or wherever dry conditions exist.

51. Blasting Agents
 Blasting agents consist of very insensitive explosives. While they do have a mass
explosion hazard, the risk of such an explosion occurring is negligible. This is because the
the blasting agent contains only small amounts of detonating substances. The key
difference between an explosive and a blasting agent lies with their sensitivity to initiation.
In contrast to explosives, blasting agents are not cap sensitive. They, therefore, need a
primer to be ignited.

52. Blasting Agents
 The problem with blasting agents
 Blasting agents are sold as commercial products to businesses like mining, quarrying etc.
this enables the black market that is available for the sale of explosive substances. With
sufficient knowledge of explosives, a bomb maker with a criminal intent can end up
causing more damage with blasting agents than explosives. Therefore, it becomes a
problem.

53. Blasting Agents
 Forensic significance of blasting agents
 Blasting agents cannot function on their own as previously explained. They always need a
primer to make them go off. This is a crucial difference and helps during forensic investigation
in a case where blasting agents have been used. In many cases, even in India, blasting agents
are slowly becoming the norm of bomb makers due to the easier availability and the means to
control the blasting agents better than the explosive. More than all this, the bomb maker has
an advantage with blasting agents because, blasting agents, container and primer can be
dismantled and carried separately to the scene and put in place there and blasted. This
reduces the risk of getting caught during transport and makes it even more easier.
 Forensically in a case involving blasting agents, the filler deposit is the major evidence. With a
few chemical tests one can make out which blasting agent has been used. Fuses differ in
cases involving blasting agents because, they need primers to function. This makes it
necessary to have a mixture of explosive substances in the crime scene and whenever one
finds a mixture, it means that you’re dealing with an experienced and more sophisticated bomb
maker. Therefore filler and fuse findings in the scene can help forensically to prove the use of
blasting agents.

54. Synthesis of TNT
 The synthesis of 2,4,6-trinitrotoluene (TNT) has gained a lot of scientific and industrial
interest since it was the first high explosive that was able to fulfil the expectations of
producers and the military. It was first synthesized in the 1860s and was later produced in
large quantities during World War I and World War II.
 This explosive is a moderately powerful, high-energy material, with satisfactory thermal
stability and reduced mechanical sensitivity. It is still used in many explosive mixtures
today by military and special branches of industry. This is facilitated by its low cost and the
fact that it is relatively insensitive, as well as readily melt-castable. It is, therefore, still a
main component in many explosive mixtures, some of which were developed several
decades ago, such as Amatol, Baratol, Comp B, H-6, Tritonal, and Torpex.

55. Synthesis of TNT
 In recent years, considerable progress has been made in the synthesis of high-energy
materials, especially in the field of military high explosives or propellants. Some of these
high-energy materials can be obtained by novel eco-friendly methods of synthesis or
techniques. Nevertheless, the traditional approach is still applied, and it involves the use
of hazardous concentrated acid mixtures (typically nitric and sulfuric acid as a nitrating
mixture.
 Nitration processes carried out especially at a larger scale are particularly prone to
runaway exothermic reactions, and thus are of high safety concern. High purity TNT can
be obtained after nitration of the dinitrotoluene (DNT) isomers: 2,4-DNT and 2,6-DNT. By
applying a conventional synthesis, highly concentrated nitric acid (100%) and oleum
(sulfuric acid containing up to 60% SO3) are required to achieve a conversion rate higher
than 98% as required for military grade TNT This way of synthesis presents safety
concerns since the handling, mixing, and disposal of oleum with anhydrous nitric acid is
particularly dangerous.

56. Synthesis of TNT
 Several methods for TNT synthesis or nitration of aromatic compounds other than the
traditional method are patented or reported in the literature.
 They focus mainly on improving the process by achieving higher purity, faster reaction
times, and more environmentally friendly approaches.
 Some examples include the methods developed by Millar et al., who performed the
nitration of DNT in batch mode by using N2O5/H2SO4 98% as the nitrating mixture,
Lagoviyer et al. that used sodium nitrate/molybdenum oxide for nitration of toluene, and
Kyler et al. that patented the use of 98–99% nitric acid with trifluoromethanesulfonic acid
for the conversion of DNT to TNT. Today a latest tech uses flow chemistry technique to
convert DNT to TNT.

57. Synthesis of TNT

58. Characteristics of TNT
 TNT is a yellow, odorless solid that does not occur naturally in the environment. It is made
by combining toluene with a mixture of nitric and sulfuric acids.
 It is a highly explosive, single-ring nitroaromatic compound that is a crystalline solid at
room temperature.
 Effluent from TNT manufacturing is a major source of munitions constituent contamination
in soils, groundwater and occasionally surrounding surface water and sediment at Army
ammunition plants.

59. Characteristics of TNT
 TNT is one of the most widely used military high explosives, partly because of its
insensitivity to shock and friction. It has been used extensively in the manufacture of
explosives since the beginning of the 20th century and is used in military cartridge
casings, bombs and grenades.
 It has been used either as a pure explosive or in binary mixtures. The most common
binary mixtures of TNT are cyclotols (mixtures with RDX) and octols (mixtures with
octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine [HMX]).
 In addition to military use, small amounts of TNT are used for industrial explosive
applications, such as deep well and underwater blasting. Other industrial uses include
chemical manufacturing as an intermediate in the production of dyestuffs and
photographic chemicals

60. Characteristics of TNT
 TNT is commonly found at hand grenade ranges, antitank rocket ranges, artillery ranges,
bombing ranges, munitions testing sites and open burn/open detonation (OB/OD) sites.
 Production of TNT in the United States is currently limited to military arsenals; however, it
may be imported into the United States for industrial applications.

61. Characteristics of TNT

62. Synthesis of PETN
 The PETN compound finds both medicinal use as a coronary Vasodilator (often mixed
with lactose to reduce sensitivity) and extensive use in the explosive industry, as a very
high power booster in blasting caps and also as the filler in detonating fuse.
 To synthesize PETN, the base requirements are concentrated sulphuric acid,
concentrated nitric acid, acetone, pentaerythitol, Distilled water and Sodium bicarbonate.
All these are easily available items and therefore PETN is commonly synthesized illegally.
 34 ml of 65% HNO3, 24,8 ml of 96% H2SO4 and 10,0 g of Pentaerythritol are mixed.

63. Synthesis of PETN
 The mixture is placed in a cold water bath and allowed to chill. This process can produce
too high temperatures and is a risky step to perform.
 Keep stirring the contents till the mixture is cold enough to handle.
 As cooling takes place, the mixture will also thicken and becomes a thick slurry.
 The critical point is to maintain the temperature to as cool as possible. Otherwise the
entire setup catches fire and goes waste. Sometimes even results in explosion.
 After the slurry is formed, the slurry is now heated in a hot water batch for 25 minutes at
45C.
 the mixture is then diluted using 450ml of ice cold distilled water.

64. Synthesis of PETN
 Filtered and neutralized using sodium bicarbonate.
 200ml of acetone is added and stirred until the slurry dissolves.
 The mixture is filtered again and poured into a beaker containing 600 ml of ice cold
distilled water.
 Again filtered and poured into a beaker containing 600ml ice cold distilled water.
 This causes the PETN to precipitate at the bottom into fine crystals.
 Decant or filter to preserve the crystalline PETN.
 PETN is seen as white amorphous powder substance.

65. Characteristics of PETN
 PETN is more powerful an explosive than TNT. It is more sensitive to shock and is an
uncontrollable explosive largely.
 I tis practically insoluble in water, very less soluble in organic compounds like acetone or
alcohol.
 It has a high melting point and can withstand heat, making it even more dangerous in
accidental explosions in large quantities.
 It is toxic if swallowed and may cause damage to internal organs when prolonged
exposure occurs (if ingested).
 It is also a medicinal product. Therefore, it is available to drug companies against a
license in small quantities.
 The black market for PETN is quite high and military sellouts also have been reported in
the west.

66. Synthesis of RDX
 RDX is usually contaminated with HMX during synthesis.
 Avoiding this contamination involves a 2 step process
 Synthesis of R-salt (where HMX synthesizers are absent)
 Using R salt to synthesise RDX

67. Synthesis of RDX
 Synthesis of R – Salt (1,3,5-trinitroso-l,3,5-trlazacyclohexane)
 To a stirred solution of 21g (0.15 mol)of hexaminein, 280 mL of water and 120g of ice is
added followed by an ice-coldsolution of 68 mL of cold conc. HCI and200g of ice.
 The acid solution is stirred while a solution of 50g (0.72 mol) of NaNO2 in 50 mL of water
and30g of ice is added.
 The reaction mixture turns blue and then green and foamed up with the precipitate rising
to the surface. The mixture is then allowed to stand 0.5h without stirring. The precipitate is
collected by suction filtration, washed with water, and air-dried to give 10.5g (40%) of a
light yellow powder. Recrystallization from EtOH (95ml) yielded 9.5g of light yellow plates.
This is the R-salt which has a melting point of 106-107C.

68. Synthesis of RDX
 Synthesis of RDX
 To 194 ml of conc nitric acid cooled to -40C add 4.7ml of H2O2.
 To this mixture add 9.5g of R-salt in small proportions and vigorously stir over a 40
minutes period.
 After the addition of reaction mixture, warm to room temperature and stir for 2 hours.
 Pour the mixture onto 550g of ice and collect the resulting white solid by suction.
 Wash the solid with water and air dry.
 Recrystallise from 75ml of acetic acid.
 The white crystals formed are RDX crystals.

69. RDX - Research Department eXplosive or
Royal Demolition eXplosive
 C3H6N6O6 - Cyclo, tri, methylene, tri, nitramine.
 Patented in 1898, used widely in 2nd world war by the UK.
 US had a secret development programme post - world war. Produced large scale
RDX.
 RDX are solid crystals, white in color - insoluble in water and organic solvents.

70. Characteristics of RDX
 Seen as white crystals and is considered as a high explosive.
 RDX’s major strength is that it is insoluble in water and therefore difficult to defuse.
 RDX has been in news for many cases in the past – the latest being the Pulwama attack
on the CRPF jawans on 2018.
 It causes maximum mechanical damage as well as takes away lives.

71. Review
 Explosives
 Types
 IEDs vs SEDs
 High explosives
 Home made explosives
 Military explosives
 Blasting agents
 Synthesis of PETN
 Synthesis of TNT
 Synthesis of RDX
 Explosion process
 Blast waves
 Vitrolage
 V&AC Trap cases

72. Explosion process
 Explosion is a chemical process - exothermic decomposition (a chemical decomposition
process initiated due to heat generation).
 This happens in 2 steps
 Deflagration and
 Detonation
 During deflagration, due to the initiating heat / friction or signal there is burning which
leads to increase in the heat generated and therefore increase in the rate of
decomposition (reaction) and starts to lead into a self-sustained reaction.
 During detonation, the initiation, deflagration and the confinement lead to a supersonic
state of reaction, which can result in multiple effects depending on the build of the
explosive.

73. Explosion process
 The detonation process is understood in different steps as it progresses:
 A shock front is formed which propagates at a characteristic velocity through the explosive
and starts to build up the pressure and temperature due to the chemical reaction.
 After the shock front, the chemical reaction starts rapidly detonating.
 This leads to further accumulation of heat and pressure which finally gives way and the
explosive goes off.

74. Explosion process

75. Explosion process
 Effects due to an explosion
 As already discussed in a previous lecture explosion effects may be
 Thermal effect
 The thermal energy released is dependent on the heat produced by the filler while deflagrating
and the decomposition rate.
 Pressure effect
 The magnitude of pressure associated with an explosion is dependent on the volume of
explosive container, the gas that is produced and the temperature at which it is detonating.
 Fragmentation effect
 The fragmentation effect is one of the most felt effect as it causes the fatalities to pile up. It is
dependent on the container's material and the improvisation involved as well as the
environment in which the bomb goes off.
 Shock effect
 The shock wave effect is in fact one of the least understood effect of bombs. It can affect an
object even far away from the scene of explosion and therefore it has its own seriousness.

76. Explosion process
 Other than these effects, the explosive can cause effects such as
 Oxygen imbalance
 Negative pressure
 Mechanical failures
 Ecological damages

77. Blast waves
 Blast waves are a crucial effect of explosives. This can cause
damages beyond the location of the bomb and therefore are
accounted to much more damage than originally planned for.
 These blast waves are usually high in energy and can reach super-
sonic speed (faster than sound waves) and can rip through
mechanical structures, cause a mental imbalance in victims and
also make the scene muted for a short span of time.

78. Blast waves
 The shock waves owe their energy to the wave energy created by
the positive and negative pressure which occur in quick
succession, kinetic energy due to the gasses breaking apart the
bomb, the potential energy of the fragments and fillers and the
radiation energy released along with all this.
 The kinetic and potential energy help the shock waves to travel
long distances in record speeds and therefore a bomb becomes
quite difficult to understand with respect to its effects.
 Blast waves therefore need to be understood as 'anything s
possible' scenarios and the same must be kept in mind during
investigation of a case of explosion.

79. Blast waves
 Effects of a blast wave
 When a shock wave hits a mechanical structure it can break it
down completely or cause partial damage. The damage is usually
observed as strong and immediate.
 In contrast blast waves can also be reflected off from mechanical
structures and cause grazing damages which may be observed as
scrapings on walls, shattering of nearby breakable items etc.

80. Blast waves
 Findings of blast wave during investigation
 During investigation, it becomes difficult to document blast wave hazards.
While it is not easy to document the other hazards, blast wave hazard is
tricky and the investigator needs to be careful in his depth of
investigation. The best practise is to gather as much public testimony as
possible, collect interviews and review social media posts of the incident
and get in touch with everyone who has been affected by the shock
waves produced by the explosion.
 The eye witness testimonies are then used to reconstruct what may have
possibly happened due to the blast wave.
 Insurance claims, victim assistance etc. depend on these investigation
reconstruction reports in order to complete their cycle.