What Is Nitroglycerin?
Nitroglycerin is an organic compound used as a powerful explosive and a medicinal agent for angina pectoris. While commonly associated with the term “nitro” in both contexts, it’s important to distinguish that nitroglycerin is a nitrate ester rather than a nitro compound.
The handling of undiluted nitroglycerin requires utmost care due to its extreme sensitivity to vibrations or friction, which can lead to accidental detonations. Nonetheless, with proper safety measures, the risk of explosion can be significantly reduced, although historical lack of safe handling practices led to frequent accidents.
Uses of Nitroglycerin
Nitroglycerin finds its primary applications in the fields of explosives and pharmaceuticals. Its explosive properties, triggered by heat, vibration, and friction, make it a key ingredient in dynamite, where it’s mixed with nitrocellulose to create nitrogel. In dynamite, the composition includes at least 6% nitroglycerin.
Medically, nitroglycerin is utilized to treat angina pectoris. Administered as a sublingual tablet, it undergoes metabolic processes to release nitrite, which then converts to nitric oxide. This process leads to the relaxation of vascular smooth muscles and dilation of blood vessels, providing relief from angina symptoms.
Properties of Nitroglycerin
This compound is characterized by its colorless or pale yellow oily appearance, poor water solubility, and good solubility in organic solvents. It melts at 14°C and decomposes at temperatures between 50-60°C. Its high sensitivity to impact and friction necessitates careful handling to prevent accidental detonation.
Strategies to reduce nitroglycerin’s sensitivity include dilution with water or acetone or its conversion into nitrogel. The compound, with the formula C3H5(ONO2)3, has a molecular weight of 227.0865g/mol and a density of 1.6g/cm3 at 15°C. Its molecular structure features tetrahedral carbon atoms and triangular nitrogen atoms.
Other Information on Nitroglycerin
1. Synthesis Method of Nitroglycerin
Discovered by Ascanio Sobrero in 1847, nitroglycerin is synthesized by esterifying glycerin with nitric acid, transforming it into a nitrate ester.
2. Storage of Nitroglycerin
To store nitroglycerin safely, it should be frozen at 8°C and is known to thaw at 14°C. The compound exhibits increased sensitivity when partially frozen, making it more prone to explosion. Repeated freeze-thaw cycles can destabilize nitroglycerin, especially in gel form, necessitating controlled temperature storage to avoid melting or freezing, especially in its dynamite form.
3. How to Use Nitroglycerin
For melting, nitroglycerin should be heated indirectly in a double boiler, ensuring that air does not become trapped around the jar’s rim and avoiding stirring to prevent detonation risks. Even when in gel form, care must be taken to avoid introducing air bubbles during processing, as this can lead to explosive outcomes.
4. Compounds Related to Nitroglycerin
Nitroglycerin, a nitrate ester of glycerin, shares its origins with glycerin—a clear, colorless liquid known for its sweet taste. Glycerin’s versatility sees it used in various applications, including as a preservative, sweetener, humectant, stabilizer in food, and as an ingredient in cosmetics and medicines.