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Low explosives and uses; glycerol trinitrate

Short answer

Low explosives deflagrate, producing a pushing effect; used as propellants in guns, rockets, fireworks, and for gentle blasting. GTN is prepared by nitrating glycerol with HNO₃/H₂SO₄ below 15°C. It is used in dynamite, gelignite, cordite, blasting, and as a vasodilator for angina.

What are low explosives? Write their uses. Give the preparation and applications of glycerol trinitrate.

Low explosives

Low explosives burn rapidly (deflagrate) instead of detonating; the burning front travels at a few metres per second up to about 400 m/s. The gases produced give a pushing (propelling) effect rather than a shattering one. They are used as propellants and for gentle blasting. Examples: black powder (gunpowder: KNO₃ + charcoal + S) and smokeless powder. Uses: firing bullets and shells, rocket propellants, quarrying soft rock, fireworks and safety fuses.

Preparation of glycerol trinitrate (GTN, nitroglycerine, TNG)

GTN is made by nitrating glycerol with a mixture of conc. HNO₃ and conc. H₂SO₄ (the sulfuric acid absorbs the water formed). The temperature is kept below 10–15 °C by cooling, because higher temperatures can cause an explosion.

CH₂OH                      CH₂ONO₂
|                          |
CHOH  + 3HNO₃ --H₂SO₄-->   CHONO₂  + 3H₂O
|                          |
CH₂OH                      CH₂ONO₂

The oily layer of GTN is separated, washed with water and sodium carbonate solution, and dried. It is a colourless to pale yellow oily liquid, very sensitive to shock, and explodes violently: 4C₃H₅(ONO₂)₃ → 12CO₂ + 10H₂O + 6N₂ + O₂

Uses

  • Making dynamite (absorbed in kieselguhr), blasting gelatin and gelignite.
  • Component of smokeless propellants such as cordite.
  • Blasting in mining and tunnelling.
  • In dilute form, a medicine (vasodilator) for angina.

✓ Answer checked by Claude Opus 5.5 (high effort)

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