- 2075 Baisakh · 2.5+2.5 marks
High vs plastic explosives; TNT
Short answer
High explosives are solid/liquid, cannot be moulded; plastic explosives are putty-like, mouldable mixtures of RDX/PETN and plasticizer. TNT is prepared by stepwise nitration of toluene with HNO₃/H₂SO₄; used in ammunition, mining, demolition.
Write the points of difference between high explosives and plastic explosives. Mention the preparation and applications of TNT.
High explosives vs plastic explosives
| Basis | High explosive | Plastic explosive |
|---|---|---|
| Physical state | Solid (crystalline/powder) or liquid | Soft, putty-like, dough-like mass |
| Moulding | Cannot be moulded | Can be moulded by hand into any shape |
| Composition | Single compound or mixture (TNT, PETN) | High explosive (RDX/PETN) + plasticiser |
| Handling | Cast or pressed into containers | Safe and easy to shape and fix on objects |
| Water resistance | Varies | Generally waterproof |
| Examples | TNT, picric acid, dynamite | C-4, Semtex |
Preparation of TNT (2,4,6-trinitrotoluene)
TNT is made by the stepwise nitration of toluene with a mixture of conc. HNO₃ and conc. H₂SO₄ (H₂SO₄ is a dehydrating agent, giving NO₂⁺). Toluene itself is obtained from benzene by Friedel–Crafts methylation (benzene + CH₃Cl, anhydrous AlCl₃).
C₆H₆ + CH₃Cl --AlCl₃--> C₆H₅CH₃ + HCl (toluene)
C₆H₅CH₃ --HNO₃/H₂SO₄, 30°C--> mononitrotoluene
--HNO₃/H₂SO₄, 60°C--> dinitrotoluene
--HNO₃/oleum, 100-110°C--> 2,4,6-trinitrotoluene
Structure of TNT (ring carbons C1 to C6)
CH₃
|
.----C1---.
O₂N--C2 C6--NO₂
| |
C3 C5
'---C4----'
|
NO₂
The product is washed with water and dilute sodium carbonate and recrystallised from alcohol. It is a pale yellow crystalline solid, m.p. 81 °C. Decomposition: 2C₇H₅N₃O₆ → 3N₂ + 5H₂O + 7CO + 7C
Uses
- Filling for shells, bombs, grenades, torpedoes and mines.
- Mining, quarrying and demolition (alone or as amatol/ammonal mixtures).
- Raw material for other explosives and dyes.
✓ Answer checked by Claude Opus 5.5 (high effort)
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