Nitroglycerin
Overview
 
Nitroglycerin also known as nitroglycerine, trinitroglycerin, trinitroglycerine, 1,2,3-trinitroxypropane and glyceryl trinitrate, is a heavy, colorless, oily, explosive liquid produced by nitrating
Nitration
Nitration is a general chemical process for the introduction of a nitro group into a chemical compound. The dominant application of nitration is for the production of nitrobenzene, the precursor to methylene diphenyl diisocyanate...

 glycerol
Glycerol
Glycerol is a simple polyol compound. It is a colorless, odorless, viscous liquid that is widely used in pharmaceutical formulations. Glycerol has three hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature. The glycerol backbone is central to all lipids...

. Since the 1860s, nitroglycerin has been used as an active ingredient in the manufacture of explosives, mostly dynamite
Dynamite
Dynamite is an explosive material based on nitroglycerin, initially using diatomaceous earth , or another absorbent substance such as powdered shells, clay, sawdust, or wood pulp. Dynamites using organic materials such as sawdust are less stable and such use has been generally discontinued...

, and as such it is employed in the construction
Construction
In the fields of architecture and civil engineering, construction is a process that consists of the building or assembling of infrastructure. Far from being a single activity, large scale construction is a feat of human multitasking...

, demolition
Demolition
Demolition is the tearing-down of buildings and other structures, the opposite of construction. Demolition contrasts with deconstruction, which involves taking a building apart while carefully preserving valuable elements for re-use....

, and mining
Mining
Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...

 industries.
Encyclopedia
Nitroglycerin also known as nitroglycerine, trinitroglycerin, trinitroglycerine, 1,2,3-trinitroxypropane and glyceryl trinitrate, is a heavy, colorless, oily, explosive liquid produced by nitrating
Nitration
Nitration is a general chemical process for the introduction of a nitro group into a chemical compound. The dominant application of nitration is for the production of nitrobenzene, the precursor to methylene diphenyl diisocyanate...

 glycerol
Glycerol
Glycerol is a simple polyol compound. It is a colorless, odorless, viscous liquid that is widely used in pharmaceutical formulations. Glycerol has three hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature. The glycerol backbone is central to all lipids...

. Since the 1860s, nitroglycerin has been used as an active ingredient in the manufacture of explosives, mostly dynamite
Dynamite
Dynamite is an explosive material based on nitroglycerin, initially using diatomaceous earth , or another absorbent substance such as powdered shells, clay, sawdust, or wood pulp. Dynamites using organic materials such as sawdust are less stable and such use has been generally discontinued...

, and as such it is employed in the construction
Construction
In the fields of architecture and civil engineering, construction is a process that consists of the building or assembling of infrastructure. Far from being a single activity, large scale construction is a feat of human multitasking...

, demolition
Demolition
Demolition is the tearing-down of buildings and other structures, the opposite of construction. Demolition contrasts with deconstruction, which involves taking a building apart while carefully preserving valuable elements for re-use....

, and mining
Mining
Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...

 industries. Similarly, since the 1880s, it has been used by the military as an active ingredient, and a gelatinizer for nitrocellulose
Nitrocellulose
Nitrocellulose is a highly flammable compound formed by nitrating cellulose through exposure to nitric acid or another powerful nitrating agent. When used as a propellant or low-order explosive, it is also known as guncotton...

, in some solid propellant
Propellant
A propellant is a material that produces pressurized gas that:* can be directed through a nozzle, thereby producing thrust ;...

s, such as Cordite
Cordite
Cordite is a family of smokeless propellants developed and produced in the United Kingdom from 1889 to replace gunpowder as a military propellant. Like gunpowder, cordite is classified as a low explosive because of its slow burning rates and consequently low brisance...

 and Ballistite
Ballistite
Ballistite is a smokeless propellant made from two high explosives, nitrocellulose and nitroglycerine. It was developed and patented by Alfred Nobel in the late 19th century.-The development of smokeless powders:...

.

Nitroglycerin is also used medically as a vasodilator to treat heart
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...

 conditions, such as angina and chronic heart failure. It is one of the oldest and most useful drugs for treating heart disease by shortening or even preventing attacks of angina pectoris. Nitroglycerin comes in forms of tablets, sprays or patches. Nitroglycerin may be able to be used to help destroy prostate cancer
Prostate cancer
Prostate cancer is a form of cancer that develops in the prostate, a gland in the male reproductive system. Most prostate cancers are slow growing; however, there are cases of aggressive prostate cancers. The cancer cells may metastasize from the prostate to other parts of the body, particularly...

.

History

Nitroglycerin was the first practical explosive ever produced that was stronger than black powder. Nitroglycerin was synthesized by the chemist
Chemist
A chemist is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties such as density and acidity. Chemists carefully describe the properties they study in terms of quantities, with detail on the level of molecules and their component atoms...

 Ascanio Sobrero in 1847, working under Théophile-Jules Pelouze
Théophile-Jules Pelouze
Théophile-Jules Pelouze was a French chemist. He was born at Valognes, and died in Paris....

 at the University of Turin
University of Turin
The University of Turin is a university in the city of Turin in the Piedmont region of north-western Italy...

. Sobrero initially called his discovery pyroglycerine, and warned vigorously against its use as an explosive. It was later adopted as a commercially useful explosive by Alfred Nobel
Alfred Nobel
Alfred Bernhard Nobel was a Swedish chemist, engineer, innovator, and armaments manufacturer. He is the inventor of dynamite. Nobel also owned Bofors, which he had redirected from its previous role as primarily an iron and steel producer to a major manufacturer of cannon and other armaments...

. Nobel experimented with several safer ways to handle the dangerous nitroglycerin after his younger brother Emil Oskar Nobel
Emil Oskar Nobel
Emil Nobel was a member of the Nobel family, the youngest son of Immanuel Nobel, the younger, and of his wife Caroline Andrietta Ahlsell. He was brother of Robert Nobel, Ludvig Nobel and Alfred Nobel. Emil died on 3 September 1864, the victim of an explosion while experimenting with...

 and several factory workers were killed in a nitroglycerin explosion at the Nobel's armaments factory in 1864 in Heleneborg
Heleneborg
Heleneborg is an estate on Södermalm, a part of the city of Stockholm, Sweden. It is opposite Långholmen island ....

, Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

.

One year later, Alfred Nobel founded Alfred Nobel & Company
Dynamit Nobel AG
Dynamite Nobel AG is a German chemical and weapons company whose headquarters was based in Troisdorf. It was founded in 1865 by Alfred Nobel.-Creation:...

 in Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 and built an isolated factory in the Krümmel hills of Geesthacht
Geesthacht
Geesthacht is the largest city in the District of the Duchy of Lauenburg in Schleswig-Holstein in Northern Germany, 34 km southeast of Hamburg on the right bank of the river Elbe.-History:*Around 800: A church is documented....

 near Hamburg
Hamburg
-History:The first historic name for the city was, according to Claudius Ptolemy's reports, Treva.But the city takes its modern name, Hamburg, from the first permanent building on the site, a castle whose construction was ordered by the Emperor Charlemagne in AD 808...

. This business exported a liquid combination of nitroglycerin and gunpowder
Gunpowder
Gunpowder, also known since in the late 19th century as black powder, was the first chemical explosive and the only one known until the mid 1800s. It is a mixture of sulfur, charcoal, and potassium nitrate - with the sulfur and charcoal acting as fuels, while the saltpeter works as an oxidizer...

 called "Blasting Oil", but this was extremely unstable and difficult to handle, as shown in numerous catastrophes. The buildings of the Krümmel factory were destroyed twice.

In April 1866, three crates of nitroglycerin were shipped to California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

 for the Central Pacific Railroad
Central Pacific Railroad
The Central Pacific Railroad is the former name of the railroad network built between California and Utah, USA that formed part of the "First Transcontinental Railroad" in North America. It is now part of the Union Pacific Railroad. Many 19th century national proposals to build a transcontinental...

, which planned to experiment with it as a blasting explosive to expedite the construction of the 1659 feet (505.7 m)-long Summit Tunnel through the Sierra Nevada Mountains. One of these crates exploded, destroying a Wells Fargo
Wells Fargo
Wells Fargo & Company is an American multinational diversified financial services company with operations around the world. Wells Fargo is the fourth largest bank in the U.S. by assets and the largest bank by market capitalization. Wells Fargo is the second largest bank in deposits, home...

 company office in San Francisco and killing 15 people. This led to a complete ban on the transportation of liquid nitroglycerin in California. The on-site manufacture of nitroglycerin was thus required for the remaining hard-rock drilling and blasting
Drilling and blasting
Before the advent of tunnel boring machines, drilling and blasting was the only economical way of excavating long tunnels through hard rock, where digging is not possible. Even today, the method is still used in the construction of tunnels, such as in the construction of the Lötschberg Base Tunnel...

 required for the completion of the First Transcontinental Railroad
First Transcontinental Railroad
The First Transcontinental Railroad was a railroad line built in the United States of America between 1863 and 1869 by the Central Pacific Railroad of California and the Union Pacific Railroad that connected its statutory Eastern terminus at Council Bluffs, Iowa/Omaha, Nebraska The First...

 in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

.

Liquid nitroglycerin was widely banned elsewhere as well, and these legal problems led to Alfred Nobel and his company's developing dynamite
Dynamite
Dynamite is an explosive material based on nitroglycerin, initially using diatomaceous earth , or another absorbent substance such as powdered shells, clay, sawdust, or wood pulp. Dynamites using organic materials such as sawdust are less stable and such use has been generally discontinued...

 in 1867. This was made by mixing nitroglycerin with diatomaceous earth
Diatomaceous earth
Diatomaceous earth also known as diatomite or kieselgur/kieselguhr, is a naturally occurring, soft, siliceous sedimentary rock that is easily crumbled into a fine white to off-white powder. It has a particle size ranging from less than 1 micrometre to more than 1 millimetre, but typically 10 to...

 (called kieselguhr) found in the Krümmel hills. Similar mixtures, such as "dualine" (1867), "lithofracteur" (1869), and "gelignite
Gelignite
Gelignite, also known as blasting gelatin or simply jelly, is an explosive material consisting of collodion-cotton dissolved in either nitroglycerine or nitroglycol and mixed with wood pulp and saltpetre .It was invented in 1875 by Alfred Nobel, who had earlier invented dynamite...

" (1875), were formed by mixing nitroglycerin with other inert absorbents, and many combinations were tried by other companies in attempts to get around Nobel's tightly-held patents for dynamite.

Dynamite mixtures containing nitrocellulose
Nitrocellulose
Nitrocellulose is a highly flammable compound formed by nitrating cellulose through exposure to nitric acid or another powerful nitrating agent. When used as a propellant or low-order explosive, it is also known as guncotton...

, which increases the viscosity of the mix, are commonly known as "gelatins".

Following the discovery that amyl nitrite
Amyl nitrite
Amyl nitrite is the chemical compound with the formula C5H11ONO. A variety of isomers are known, but they all feature an amyl group attached to the nitrito functional group. The alkyl group is unreactive and the chemical and biological properties are mainly due to the nitrite group...

 helped alleviate chest pain, Dr. William Murrell experimented with the use of nitroglycerin to alleviate angina pectoris and to reduce the blood pressure
Blood pressure
Blood pressure is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. When used without further specification, "blood pressure" usually refers to the arterial pressure of the systemic circulation. During each heartbeat, BP varies...

. He began treating his patients with small doses of nitroglycerin in 1878, and this treatment was soon adopted into widespread use after Murrell published his results in the journal The Lancet
The Lancet
The Lancet is a weekly peer-reviewed general medical journal. It is one of the world's best known, oldest, and most respected general medical journals...

in 1879. The medical establishment used the name "glyceryl trinitrate" or "trinitrin" to avoid alarming patients who associated nitroglycerin with explosions.

Wartime production rates

Large quantities of nitroglycerin were manufactured during World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

 and World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 for use as military propellants and in military engineering work. During World War I, HM Factory, Gretna
HM Factory, Gretna
His Majesty's Factory, Gretna, or H.M. Factory, Gretna as it was usually known, was a UK government World War I Cordite factory, adjacent to the Solway Firth, near Gretna, Dumfries and Galloway...

, the largest propellant factory in the Great Britain
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

, produced about 800 long ton
Long ton
Long ton is the name for the unit called the "ton" in the avoirdupois or Imperial system of measurements, as used in the United Kingdom and several other Commonwealth countries. It has been mostly replaced by the tonne, and in the United States by the short ton...

s (812 tonne
Tonne
The tonne, known as the metric ton in the US , often put pleonastically as "metric tonne" to avoid confusion with ton, is a metric system unit of mass equal to 1000 kilograms. The tonne is not an International System of Units unit, but is accepted for use with the SI...

s) of Cordite RDB per week. This amount took at least 336 tons of nitroglycerin per week (assuming no losses in production). The Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 had its own factory at Royal Navy Cordite Factory, Holton Heath
Royal Navy Cordite Factory, Holton Heath
The Royal Navy Cordite Factory, Holton Heath, , was set up at Holton Heath, Dorset in World War I to manufacture Cordite for the Royal Navy. It was reactivated in World War II to manufacture gun propellants for the Admiralty and its output was supplemented by the Royal Navy Propellant Factory,...

 in Dorset, England. A large cordite factory was also built in Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

 during World War I. The Canadian Explosives Limited
Canadian Industries Limited
Canadian Industries Limited, also known as C-I-L is a Canadian chemicals manufacturer. Products include paints, fertilizers and pesticides, and explosives. It was formed in 1910 by the merger of five Canadian explosives companies...

 cordite factory at Nobel, Ontario
Nobel, Ontario
Nobel is a village located on the shores of Parry Sound, Ontario, Canada. It is located in the Municipality of McDougall in the District of Parry Sound. The community is named after Alfred Nobel, the inventor of dynamite....

, was designed to produce 1500000 lb (680.4 t) of cordite per month. This required about 286 tonnes of nitroglycerin per month.

Instability and desensitization

In its pure form, nitroglycerin is a primary contact explosive
Contact explosive
Contact explosive generally refers to any substance that will explode when relatively small quantities of energy are applied to the substance, whether that be heat, light, sound, or physical pressure and even Alpha radiation.Examples include:...

, 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
RDX
RDX, an initialism for Research Department Explosive, is an explosive nitroamine widely used in military and industrial applications. It was developed as an explosive which was more powerful than TNT, and it saw wide use in WWII. RDX is also known as cyclonite, hexogen , and T4...

 and PETN
PETN
Pentaerythritol tetranitrate , also known as PENT, PENTA, TEN, corpent, penthrite , is the nitrate ester of pentaerythritol. Penta refers to the five carbon atoms of the neopentane skeleton.PETN is most well known as an explosive...

, as well as the plastic explosive
Plastic explosive
Plastic explosive is a specialised form of explosive material. It is a soft and hand moldable solid material. Plastic explosives are properly known as putty explosives within the field of explosives engineering....

 C-4
C-4 (explosive)
C4 or Composition C4 is a common variety of the plastic explosive known as Composition C.-Composition and manufacture:C4 is made up of explosives, plastic binder, plasticizer and usually marker or odorizing taggant chemicals such as 2,3-dimethyl-2,3-dinitrobutane to help detect the explosive and...

—which contains 90 to 92 percent of RDX
RDX
RDX, an initialism for Research Department Explosive, is an explosive nitroamine widely used in military and industrial applications. It was developed as an explosive which was more powerful than TNT, and it saw wide use in WWII. RDX is also known as cyclonite, hexogen , and T4...

 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 (41 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. 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
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

, acetone
Acetone
Acetone is the organic compound with the formula 2CO, a colorless, mobile, flammable liquid, the simplest example of the ketones.Acetone is miscible with water and serves as an important solvent in its own right, typically as the solvent of choice for cleaning purposes in the laboratory...

, or dinitrotoluene
Dinitrotoluene
2,4-Dinitrotoluene or Dinitro is an organic compound with the formula C6H32. This pale yellow crystalline solid is well known as a precursor to trinitrotoluene but is mainly used in the polymer industry....

. (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 (55.4 °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.

Detonation

Nitroglycerin and any dilutents can certainly deflagrate, i.e. burn. However, the explosive power of nitroglycerin is derived from detonation
Detonation
Detonation involves a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations are observed in both conventional solid and liquid explosives, as well as in reactive gases...

: energy from the initial decomposition causes a pressure wave or gradient that detonates the surrounding fuel. This is a self-sustained shock wave
Shock wave
A shock wave is a type of propagating disturbance. Like an ordinary wave, it carries energy and can propagate through a medium or in some cases in the absence of a material medium, through a field such as the electromagnetic field...

 that propagates through the explosive medium at some 30 times the speed of sound as a near-instantaneous pressure-induced decomposition of the fuel into a white hot gas. Detonation of nitroglycerin generates gases that would occupy more than 1,200 times the original volume at ordinary room temperature and pressure. Moreover, the heat liberated raises the temperature to about 5000 °C (9,032 °F). This is totally different from deflagration
Deflagration
Deflagration is a term describing subsonic combustion that usually propagates through thermal conductivity; hot burning material heats the next layer of cold material and ignites it. Most "fire" found in daily life, from flames to explosions, is deflagration...

, which depends solely upon available fuel regardless of pressure or shock.

Manufacturing

The industrial manufacturing process often uses a nearly 1:1 mixture of concentrated sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...

 and concentrated nitric acid
Nitric acid
Nitric acid , also known as aqua fortis and spirit of nitre, is a highly corrosive and toxic strong acid.Colorless when pure, older samples tend to acquire a yellow cast due to the accumulation of oxides of nitrogen. If the solution contains more than 86% nitric acid, it is referred to as fuming...

. This can be produced by mixing white fuming nitric acid
White fuming nitric acid
White fuming nitric acid is a storable liquid oxidizer used with kerosene and hydrazine rocket fuel. It consists of nearly pure nitric acid . WFNA is commonly specified as containing no more than 2% water and less than 0.5% dissolved nitrogen dioxide or dinitrogen tetroxide.WFNA was sometimes...

—a quite expensive pure nitric acid in which the oxides of nitrogen have been removed, as opposed to red fuming nitric acid
Red fuming nitric acid
Red fuming nitric acid is a storable oxidizer used as a rocket propellant. It consists mainly of nitric acid , also containing 13% dinitrogen tetroxide and 3% water. The dissolved nitrogen dioxide is very concentrated and can be found at room temperature...

, 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
Oleum
Oleum , or fuming sulfuric acid refers to a solution of various compositions of sulfur trioxide in sulfuric acid or sometimes more specifically to disulfuric acid ....

—sulfuric acid containing excess sulfur trioxide
Sulfur trioxide
Sulfur trioxide is the chemical compound with the formula SO3. In the gaseous form, this species is a significant pollutant, being the primary agent in acid rain. It is prepared on massive scales as a precursor to sulfuric acid.-Structure and bonding:Gaseous SO3 is a trigonal planar molecule of...

—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
Nucleophile
A nucleophile is a species that donates an electron-pair to an electrophile to form a chemical bond in a reaction. All molecules or ions with a free pair of electrons can act as nucleophiles. Because nucleophiles donate electrons, they are by definition Lewis bases.Nucleophilic describes the...

 oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 atoms. The nitro
Nitro compound
Nitro compounds are organic compounds that contain one or more nitro functional groups . They are often highly explosive, especially when the compound contains more than one nitro group and is impure. The nitro group is one of the most common explosophores used globally...

 group
Functional group
In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...

 is thus added as an ester C-O-NO2 and water is produced. This is different from an aromatic nitration reaction in which nitronium ion
Nitronium ion
The nitronium ion, or sometimes the nitryl ion , , is a generally reactive cation created by the removal of an electron from the paramagnetic nitrogen dioxide molecule, or the protonation of nitric acid....

s are the active species in an electrophilic attack on the molecule's ring system.

The addition of glycerin results in an exothermic reaction
Chemical reaction
A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, typically following the input of some type of energy, such as heat, light or electricity...

 (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 very poisonous brown nitrogen dioxide
Nitrogen dioxide
Nitrogen dioxide is the chemical compound with the formula it is one of several nitrogen oxides. is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year. This reddish-brown toxic gas has a characteristic sharp, biting odor and is a prominent...

 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 (71.6 °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.

Use as an explosive and a propellant

The main use of nitroglycerin, by tonnage, is in explosives such as dynamite and in propellants.

Nitroglycerin is an oil that may explode with heat, pressure or when it burns. It is extremely unstable, therefore dropping or bumping a container can also make it explode.

Alfred Nobel
Alfred Nobel
Alfred Bernhard Nobel was a Swedish chemist, engineer, innovator, and armaments manufacturer. He is the inventor of dynamite. Nobel also owned Bofors, which he had redirected from its previous role as primarily an iron and steel producer to a major manufacturer of cannon and other armaments...

 developed the use of nitroglycerin as a blasting explosive by mixing the nitroglycerin with inert absorbents
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....

 particularly diatomaceous earth
Diatomaceous earth
Diatomaceous earth also known as diatomite or kieselgur/kieselguhr, is a naturally occurring, soft, siliceous sedimentary rock that is easily crumbled into a fine white to off-white powder. It has a particle size ranging from less than 1 micrometre to more than 1 millimetre, but typically 10 to...

. He named this explosive dynamite
Dynamite
Dynamite is an explosive material based on nitroglycerin, initially using diatomaceous earth , or another absorbent substance such as powdered shells, clay, sawdust, or wood pulp. Dynamites using organic materials such as sawdust are less stable and such use has been generally discontinued...

 and patented it in 1867. It was supplied ready for use in the form of sticks, individually wrapped in greased water-proof paper. Dynamite and similar explosives were widely adopted for civil engineering
Civil engineering
Civil engineering is a professional engineering discipline that deals with the design, construction, and maintenance of the physical and naturally built environment, including works like roads, bridges, canals, dams, and buildings...

 tasks, such as in drilling highway
Highway
A highway is any public road. In American English, the term is common and almost always designates major roads. In British English, the term designates any road open to the public. Any interconnected set of highways can be variously referred to as a "highway system", a "highway network", or a...

 and railroad tunnel
Tunnel
A tunnel is an underground passageway, completely enclosed except for openings for egress, commonly at each end.A tunnel may be for foot or vehicular road traffic, for rail traffic, or for a canal. Some tunnels are aqueducts to supply water for consumption or for hydroelectric stations or are sewers...

s, for mining
Mining
Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...

, in quarrying, and in demolition work
Demolition
Demolition is the tearing-down of buildings and other structures, the opposite of construction. Demolition contrasts with deconstruction, which involves taking a building apart while carefully preserving valuable elements for re-use....

. Likewise, military engineer
Military engineer
In military science, engineering refers to the practice of designing, building, maintaining and dismantling military works, including offensive, defensive and logistical structures, to shape the physical operating environment in war...

s have used dynamite for construction and demolition work.

Nitroglycerin was also adapted as a military propellant, for use in guns and rifles.

Nitroglycerin is a high explosive which is so unstable that the slightest jolt, friction, or impact can cause it to detonate. The molecule contains oxygen, nitrogen, and carbon with weak chemical bond
Chemical bond
A chemical bond is an attraction between atoms that allows the formation of chemical substances that contain two or more atoms. The bond is caused by the electromagnetic force attraction between opposite charges, either between electrons and nuclei, or as the result of a dipole attraction...

s. Hence when it explodes, great energy is released as the atoms rearrange to form new molecules with strong, stable bonds such as N2, H2O, and CO2. It is the speed of the decomposition reaction which makes it such a violent explosive. A supersonic wave passing through the material causes it to decompose almost instantly. This instantaneous destruction of all molecules is called a detonation, and the destructive blast results from the rapid expansion of hot gases. Nitroglycerin has an advantage over some other high explosives, that practically no visible smoke is produced, therefore it acts as a "smokeless powder".

Because of its extreme sensitivity, nitroglycerin was rendered obsolete as a military explosive, and was replaced by less sensitive explosives such as TNT, RDX
RDX
RDX, an initialism for Research Department Explosive, is an explosive nitroamine widely used in military and industrial applications. It was developed as an explosive which was more powerful than TNT, and it saw wide use in WWII. RDX is also known as cyclonite, hexogen , and T4...

, and HMX
HMX
HMX, also called octogen, is a powerful and relatively insensitive nitroamine high explosive, chemically related to RDX. Like RDX, the name has been variously listed as High Melting eXplosive, Her Majesty's eXplosive, High-velocity Military eXplosive, or High-Molecular-weight rdX.The molecular...

. Combat engineers still use dynamite.

Alfred Nobel then developed ballistite
Ballistite
Ballistite is a smokeless propellant made from two high explosives, nitrocellulose and nitroglycerine. It was developed and patented by Alfred Nobel in the late 19th century.-The development of smokeless powders:...

, by combining nitroglycerin and guncotton. He patented it in 1887. Ballistite was adopted by a number of European governments, as a military propellant. Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

 was the first to adopt it. However, it was not adopted by the British Government. This government and the Commonwealth governments, adopted cordite
Cordite
Cordite is a family of smokeless propellants developed and produced in the United Kingdom from 1889 to replace gunpowder as a military propellant. Like gunpowder, cordite is classified as a low explosive because of its slow burning rates and consequently low brisance...

, which had been developed by Sir Frederick Abel and Sir James Dewar of the United Kingdom in 1889. The original Cordite Mk I consisted of 58% nitroglycerin, 37% guncotton, and 5.0% petroleum jelly
Petroleum jelly
Petroleum jelly, petrolatum, white petrolatum or soft paraffin, CAS number 8009-03-8, is a semi-solid mixture of hydrocarbons , originally promoted as a topical ointment for its healing properties...

. Ballistite and cordite were both manufactured in the forms of cords.

Smokeless powder
Smokeless powder
Smokeless powder is the name given to a number of propellants used in firearms and artillery which produce negligible smoke when fired, unlike the older gunpowder which they replaced...

s were originally developed using nitrocellulose as the sole explosive ingredient. Therefore they were known as single base propellants. A range of smokeless powders that contain both nitrocellulose and nitroglycerin, known as double base propellants, were also developed. Smokeless powders were originally supplied only for military use, but they were also soon developed for civilian use and were quickly adopted for sports. Some are known as sporting powders. Triple base propellants contain nitrocellulose, nitroglycerin, and nitroguanidine, but are reserved mainly for extremely high caliber ammunition rounds such as those used in tank cannons and naval artillery
Naval artillery
Naval artillery, or naval riflery, is artillery mounted on a warship for use in naval warfare. Naval artillery has historically been used to engage either other ships, or targets on land; in the latter role it is currently termed naval gunfire fire support...

.

Blasting gelatin, also known as gelignite
Gelignite
Gelignite, also known as blasting gelatin or simply jelly, is an explosive material consisting of collodion-cotton dissolved in either nitroglycerine or nitroglycol and mixed with wood pulp and saltpetre .It was invented in 1875 by Alfred Nobel, who had earlier invented dynamite...

, was invented by Nobel in 1875, using nitroglycerin, wood pulp, and sodium or potassium nitrates. This was an early low-cost, flexible explosive.

Nitroglycerin and dynamite

Alfred Nobel discovered that mixing nitroglycerin with diatomaceous earth
Diatomaceous earth
Diatomaceous earth also known as diatomite or kieselgur/kieselguhr, is a naturally occurring, soft, siliceous sedimentary rock that is easily crumbled into a fine white to off-white powder. It has a particle size ranging from less than 1 micrometre to more than 1 millimetre, but typically 10 to...

 would turn the liquid into a paste, called dynamite
Dynamite
Dynamite is an explosive material based on nitroglycerin, initially using diatomaceous earth , or another absorbent substance such as powdered shells, clay, sawdust, or wood pulp. Dynamites using organic materials such as sawdust are less stable and such use has been generally discontinued...

. An advantage of dynamite was that it could be cylinder-shaped for insertion into the drilling holes used for mining
Mining
Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...

 and tunnel
Tunnel
A tunnel is an underground passageway, completely enclosed except for openings for egress, commonly at each end.A tunnel may be for foot or vehicular road traffic, for rail traffic, or for a canal. Some tunnels are aqueducts to supply water for consumption or for hydroelectric stations or are sewers...

ing. Nobel received the American patent number 78,317 for his dynamite in 1867.

Medical use

Nitroglycerin belongs to a group of drugs called nitrates, which includes many other nitrates like isosorbide dinitrate
Isosorbide dinitrate
Isosorbide dinitrate is a nitrate used pharmacologically as a vasodilator, e.g. in angina pectoris but also for anal fissure, a condition which is known to involve decreased blood supply leading to poor healing...

 (Isordil) and isosorbide mononitrate (Imdur, Ismo, Monoket). In medicine
Medicine
Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....

, where it is generally called glyceryl trinitrate, nitroglycerin is used as a heart
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...

 medication. It is used as a medicine for angina pectoris (ischemic heart disease
Coronary heart disease
Coronary artery disease is the end result of the accumulation of atheromatous plaques within the walls of the coronary arteries that supply the myocardium with oxygen and nutrients. It is sometimes also called coronary heart disease...

) in tablets, ointment, solution for intravenous use, transdermal patches, or sprays administered sublingual
Sublingual
Sublingual, literally 'under the tongue', from Latin, refers to the pharmacological route of administration by which drugs diffuse into the blood through tissues under the tongue...

ly. Patients who experience angina when doing certain physical activities can often prevent symptoms by taking nitroglycerin 5 to 10 minutes before the activity. Some forms of nitroglycerin last much longer in the body than others. These may come in the form of a pill taken one, two, or three times per day, or even as a patch. It has been shown that round-the-clock exposure to nitrates can cause the body to stop responding normally to this medicine. Experts recommend that the patches be removed at night, allowing the body a few hours to restore its responsiveness to nitrates. Shorter-acting preparations can be used several times a day with less risk of the body getting used to this drug.
Nitroglycerin was first used to treat anginal attacks in 1879.

Angina pectoris is due to an inadequate flow of blood and oxygen to the heart. It is believed that nitroglycerin corrects the imbalance between the flow of oxygen and blood to the heart. The principal action of nitroglycerin is vasodilation
Vasodilation
Vasodilation refers to the widening of blood vessels resulting from relaxation of smooth muscle cells within the vessel walls, particularly in the large arteries, smaller arterioles and large veins. The process is essentially the opposite of vasoconstriction, or the narrowing of blood vessels. When...

—widening of the blood vessel
Blood vessel
The blood vessels are the part of the circulatory system that transports blood throughout the body. There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and...

s. Nitroglycerin will dilate veins more than arteries. It also lowers the pressure in the arteries against which the heart must pump. Dilating the veins decreases cardiac preload and leads to the following therapeutic effects during episodes of angina pectoris: subsiding of chest pain, decrease of blood pressure
Blood pressure
Blood pressure is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. When used without further specification, "blood pressure" usually refers to the arterial pressure of the systemic circulation. During each heartbeat, BP varies...

, increase of heart rate, and orthostatic hypotension
Orthostatic hypotension
Orthostatic hypotension, also known as postural hypotension, orthostasis, and colloquially as head rush or dizzy spell, is a form of hypotension in which a person's blood pressure suddenly falls when the person stands up or stretches. The decrease is typically greater than 20/10 mm Hg, and may be...

.

These effects arise because nitroglycerin is converted to nitric oxide
Nitric oxide
Nitric oxide, also known as nitrogen monoxide, is a diatomic molecule with chemical formula NO. It is a free radical and is an important intermediate in the chemical industry...

 in the body by mitochondrial aldehyde dehydrogenase
Aldehyde dehydrogenase
Aldehyde dehydrogenases are a group of enzymes that catalyse the oxidation of aldehydes.- Function :Aldehyde dehydrogenase is a polymorphic enzyme responsible for the oxidation of aldehydes to carboxylic acids, which leave the liver and are metabolized by the body’s muscle and heart...

, and nitric oxide is a natural vasodilator. Recently, it has also become popular in an off-label use at reduced (0.2%) concentration in ointment form as an effective treatment for anal fissure
Anal fissure
An anal fissure is a break or tear in the skin of the anal canal. Anal fissures may be noticed by bright red anal bleeding on the toilet paper, sometimes in the toilet. If acute they may cause severe periodic pain after defecation but with chronic fissures pain intensity is often less...

.

Industrial exposure

Infrequent exposure to high doses of nitroglycerin can cause severe headaches known as "NG head". These headaches can be severe enough to incapacitate some people; however, humans develop a tolerance to and dependence on nitroglycerin after long-term exposure. Withdrawal can (rarely) be fatal; withdrawal symptoms include headaches and heart problems; with re-exposure to nitroglycerin, these symptoms may disappear.

For workers in nitroglycerin (NTG) manufacturing facilities, this can result in a "Monday morning headache" phenomenon for those who experience regular nitroglycerin exposure in the workplace leading to the development of NTG tolerance for the vasodilating effects. Over the weekend the workers lose the tolerance to NTG and when they are reexposed on Monday the prominent vasodilation
Vasodilation
Vasodilation refers to the widening of blood vessels resulting from relaxation of smooth muscle cells within the vessel walls, particularly in the large arteries, smaller arterioles and large veins. The process is essentially the opposite of vasoconstriction, or the narrowing of blood vessels. When...

 produces tachycardia
Tachycardia
Tachycardia comes from the Greek words tachys and kardia . Tachycardia typically refers to a heart rate that exceeds the normal range for a resting heart rate...

, dizziness, and a headache.

See also

  • Erythritol tetranitrate
    Erythritol tetranitrate
    Erythritol tetranitrate is an explosive compound chemically similar to PETN. It is however thought to be 1/3 more sensitive to friction and impact. ETN is not well known, but in recent years has been used by amateur experimenters to replace PETN in improvised detonation cord or in boosters to...

  • Ethylene glycol dinitrate
  • Mannitol hexanitrate
  • Methyl nitrate
    Methyl nitrate
    Methyl nitrate is the methyl ester of nitric acid and has the chemical formula CH3NO3.Methyl nitrate is toxic and a sensitive explosive. It causes headaches when fumes are inhaled...

  • Xylitol pentanitrate
    Xylitol pentanitrate
    Xylitol pentanitrate is a rarely used liquid explosive compound with extremely high viscosity formed by completely nitrating xylitol, a sugar alcohol compound with five carbon atoms. In pure form it is a white crystalline explosive, much like other fully nitrated polyols...


External links

- 1866 Newspaper article
  • WebBook page for C3H5N3O9
  • The Tallini Tales of Destruction Detailed and horrific stories of the historical use of nitroglycerin-filled torpedoes
    Torpedo (petroleum)
    A torpedo is an explosive device used, especially in the early days of the petroleum industry, to fracture the surrounding rock at the bottom of an oil well to stimulate the flow of oil and to remove built-up paraffin wax that would restrict the flow. Earlier torpedoes used gunpowder, but the use...

    to restart petroleum wells.
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