Nitroglycerin

Nitroglycerine is also a main component in double-based smokeless gunpowders used by reloaders. Combined with nitrocellulose, there are hundreds of (powder) combinations used by rifle, pistol, and shotgun reloaders. Nitroglycerin is also used [|medically] as a [|vasodilator] to treat [|heart] conditions, such as [|angina] and [|chronic heart failure]. Nitroglycerine has been one of the oldest and most useful drugs for treating and preventing attacks of [|angina pectoris]. After more than 130 years of such use, in 2002 it was discovered that these effects arise because nitroglycerin is converted to [|nitric oxide] in the body by mitochondrial [|aldehyde dehydrogenase], [|[1]] and nitric oxide is a natural vasodilator in the body. Nitroglycerin comes in forms of tablets, sprays or patches. [|[2]] It has been suggested for other uses also, such as an adjunct therapy in [|prostate cancer].
 * Nitroglycerin** (**NG**), also known as **nitroglycerine,** **trinitroglycerin**, **trinitroglycerine**, **1,2,3-trinitroxypropane** and **glyceryl trinitrate**, is a heavy, colorless, oily, [|explosive] liquid produced by [|nitrating] [|glycerol] . Chemically, the substance is an organic [|nitrate] compound rather than a [|nitro] compound, but the traditional name is often retained. Since the 1860s, nitroglycerin has been used as an active ingredient in the manufacture of [|explosives], mostly [|dynamite] , and as such it is employed in the [|construction] , [|demolition] , and [|mining] industries. Similarly, since the 1880s, it has been used by the military as an active ingredient, and a gelatinizer for [|nitrocellulose] , in some solid [|propellants] , such as [|Cordite] and [|Ballistite].

Nitorglycerin or NG is a heavy colorless oily explosive liquid. it is used as the active ingredient in explosives such as dynamite. it is also used in medicine to treat heart conditions. It was famously manufactured and used by Alfred Noble to make his fortune.



**Dynamite**

Instability and desensitization
In its pure form, nitroglycerin is a primary [|contact explosive], with physical shock causing it to explode, and it degrades over time to even more unstable forms. This makes nitroglycerin highly dangerous to transport or use. In this undiluted form, it is one of the world's more powerful explosives, comparable to the more recently-developed [|RDX] and [|PETN], as well as the [|plastic explosive] [|C-4] —which contains 90 to 92 percent of [|RDX] as its active ingredient. Early in the history of nitroglycerin, it was discovered that liquid nitroglycerin can be "desensitized" by cooling it to about 5 to 10 °C (40 to 50 °F). At this temperature nitroglycerin freezes, contracting upon solidification. However, thawing it out can be extremely sensitizing, especially if impurities are present or if the warming is too rapid. [|[8]] It is possible to chemically "desensitize" nitroglycerin to a point where it can be considered approximately as "safe" as modern [|high explosives], such as by the addition of approximately 10 to 30 percent [|ethanol] , [|acetone] , [|[9]] or [|dinitrotoluene]. (The percentage varies with the desensitizing agent used.) Desensitization requires extra effort to reconstitute the "pure" product. Failing this, it must be assumed that desensitized nitroglycerin is substantially more difficult to detonate, possibly rendering it useless as an explosive for practical application. A serious problem in the use of nitroglycerin results from its high freezing point 13 °C (55 °F). Solid nitroglycerin is much less sensitive to shock than the liquid, a feature that is common in explosives. In the past, nitroglycerin was often shipped in the frozen state, but this resulted in a high number of accidents during the thawing process just before its use. This disadvantage is overcome by using mixtures of nitroglycerin with other polynitrates. For example, a mixture of nitroglycerin and [|ethylene glycol dinitrate] freezes at−29 °C (−20 °F). [|[10]]

Manufacturing
The industrial manufacturing process often uses a nearly 1:1 mixture of concentrated [|sulfuric acid] and concentrated [|nitric acid]. This can be produced by mixing [|white fuming nitric acid] —a quite expensive pure nitric acid in which the oxides of nitrogen have been removed, as opposed to [|red fuming nitric acid], which contains nitrogen oxides—and concentrated sulfuric acid. More often, this mixture is attained by the cheaper method of mixing fuming sulfuric acid, also known as [|oleum] —sulfuric acid containing excess [|sulfur trioxide] —and [|azeotropic] nitric acid (consisting of about 70 percent nitric acid, with the rest being water). The sulfuric acid produces protonated nitric acid species, which are attacked by glycerin's [|nucleophilic] [|oxygen] atoms. The [|nitro] [|group] is thus added as an ester C-O-NO2 and water is produced. This is different from an aromatic nitration reaction in which [|nitronium ions] are the active species in an electrophilic attack on the molecule's ring system. The addition of glycerin results in an [|exothermic reaction] (i.e., heat is produced), as usual for mixed-acid nitrations. However, if the mixture becomes too hot, it results in "runaway", a state of accelerated nitration accompanied by the destructive oxidizing of organic materials of nitric acid and the release of poisonous [|nitrogen dioxide] gas at high risk of an explosion. Thus, the glycerin mixture is added slowly to the reaction vessel containing the mixed acid (not acid to glycerin). The nitrator is cooled with cold water or some other coolant mixture and maintained throughout the glycerin addition at about 22 °C (72 °F), much below which the esterification occurs too slowly to be useful. The nitrator vessel, often constructed of iron or lead and generally stirred with compressed air, has an emergency trap door at its base, which hangs over a large pool of very cold water and into which the whole reaction mixture (called the charge) can be dumped to prevent an explosion, a process referred to as drowning. If the temperature of the charge exceeds about 30 °C (86 °F)(actual value varying by country) or brown fumes are seen in the nitrator's vent, then it is immediately drowned.