Acetone peroxide
Encyclopedia
Acetone peroxide is an organic peroxide
and a primary high explosive. It takes the form of a white crystalline powder with a distinctive bleach-like odor.
It is susceptible to heat, friction, and shock
. The instability is greatly altered by impurities, including its own oligomers. It is normally fairly stable when pure trimer. It is not easily soluble in water. It is more stable and less sensitive when wet.
. He was the first chemist to use inorganic acids as catalysts. He was also the first researcher to receive a patent for using the peroxide as an explosive compound. In 1900 Bayer and Villiger described in the same journal the first synthesis of the dimer and also described use of acids for the synthesis of both peroxides. Information about these procedures including the relative proportions of monomer
, dimer, and trimer is also available in an article by Milas and Golubović. Other sources include crystal
structure and 3d analysis in The Chemistry of Peroxides edited by Saul Patai (pp. 396–7), as well as the Textbook of Practical Organic Chemistry by Vogel.
trimer
TCAP (tri-cyclic acetone peroxide, or tri-cyclo, C
9H
18O
6) obtained by a reaction between hydrogen peroxide
and acetone
in an acid-catalyzed nucleophilic addition
. The dimer (C6H12O4) and open monomer
are also formed, but under proper conditions the cyclic trimer is the primary product. A tetrameric
form was also described. In mildly acid
ic or neutral conditions, the reaction is much slower and produces more monomer
ic organic peroxide
than the reaction with a strong acid catalyst. Due to significant strain
of the chemical bonds
in the dimer and especially the monomer, they are even more unstable than the trimer.
At room temperature, the trimeric form slowly sublimes
, reforming as larger crystals of the same peroxide.
Acetone peroxide is notable as a high explosive not containing nitrogen
. This is one reason why it has become popular with terrorists, as it can pass through scanners designed to detect nitrogenous explosives.
TCAP generally burns when ignited, unconfined, in quantities less than about 4 grams. More than 4 grams will usually detonate
when ignited; smaller quantities might detonate when even slightly confined. Completely dry TCAP is much more prone to detonation than the fresh product still wetted with water or acetone. The oxidation that occurs when burning is:
Theoretical examination of the explosive decomposition
of TCAP, in contrast, predicts "formation of acetone
and ozone
as the main decomposition products and not the intuitively expected oxidation products." This result is in good agreement with the results of 60 years of the study of controlled decompositions in various organic peroxides. It is the rapid creation of gas from a solid that creates the explosion. Very little heat is created by the explosive decomposition of TCAP. Recent research describes TCAP decomposition as an entropic explosion
.
The high sensitivity to shock, heat and friction are due to the instability
of the molecule
. Big crystals, found in older mixtures, are more dangerous, as they are easier to shatter—and initiate—than small ones.
Due to the low cost and ease with which the precursors can be obtained, acetone peroxide can be manufactured by those without the resources needed to manufacture or buy more sophisticated explosives. When the reaction is carried out without proper equipment the risk of an accident is significant. Simply mixing sulfuric acid, hydrogen peroxide, and acetone can create the substance. Crystals of AP soon precipitate out.
There is a common myth that the only "safe" acetone peroxide is the trimer, made at low temperatures:
The trimer is the more stable form, but is not much more stable than the dimer. All forms of acetone peroxide are sensitive to initiation
. Organic peroxides are sensitive, dangerous explosives; due to their sensitivity they are rarely used by well funded militaries. Even for those who synthesize explosives as a hobby there are far safer explosives with syntheses nearly as simple as that of acetone peroxide.
Acetone peroxide is commonly combined with nitrocellulose
by dissolving the nitrocellulose in acetone and then mixing in the acetone peroxide
and letting it dry, this results in a mixture that is both more stable and somewhat more powerful than acetone peroxide by itself. This mixture is commonly referred to as APNC.
Tetrameric acetone peroxide is more chemically stable (heating to 120°C for 4 hours), but despite this, it is still a very dangerous primary explosive. It can be prepared using tin(IV) chloride
(without acid present) as a catalyst with up to 40% yield if radical
inhibitor
such as hydroquinone
, or a chelator such as EDTA
is added.
It evaporates 6.5% in 24 h at 14–18°C. Openly at air at 25°C has a loss by sublimation of 68.6% in 14 days. Many accidents resulted from the fact that acetone peroxide detonates due to its sublimation characteristics within fewer days by crystallization in the range of the container cap, when opening the same. Keeping it wet stops the sublimation and can prevent this type of accident.
s of oxidation reactions, such as those used in phenol
syntheses. Due to their explosivity, they are hazardous. Numerous methods are used to reduce their production – shifting the pH
to more alkaline, adjusting the reaction temperature, or adding a soluble copper
(II) compound.
Acetone peroxide and benzoyl peroxide
are used as flour bleaching agent
s to bleach
and "mature" flour
.
Ketone peroxides
, including acetone peroxide, methyl ethyl ketone peroxide
, and benzoyl peroxide
, find applications as initiator
s for polymerization
reactions of e.g. silicone
or polyester
resin
s, often encountered when making fiberglass
-reinforced composites. For these uses, the peroxides are typically in the form of a dilute solution in an organic solvent, though even commercial products with higher concentrations of organic peroxides can form crystals around the lid when older, making the can shock-sensitive. Methyl ethyl ketone is more common for this purpose, as it is stable in storage.
is mixed with acetone while making fiberglass composites, and left to stand for some time, or when a mixture of peroxide and hydrochloric acid from printed circuit board
etching is mixed with waste acetone from cleaning the finished board and allowed to stand. While amounts obtained this way are typically much smaller than from intentional production, they are also less pure and prepared without cooling, and hence very unstable.
It is also a hazardous by-product of isosafrole
oxidation in acetone, a step in the synthesis of MDMA.
Organic peroxide
Organic peroxides are organic compounds containing the peroxide functional group . If the R' is hydrogen, the compound is called an organic hydroperoxide. Peresters have general structure RCOOR. The O-O bond easily breaks and forms free radicals of the form RO·...
and a primary high explosive. It takes the form of a white crystalline powder with a distinctive bleach-like odor.
It is susceptible to heat, friction, and shock
Shock (mechanics)
A mechanical or physical shock is a sudden acceleration or deceleration caused, for example, by impact, drop, kick, earthquake, or explosion. Shock is a transient physical excitation....
. The instability is greatly altered by impurities, including its own oligomers. It is normally fairly stable when pure trimer. It is not easily soluble in water. It is more stable and less sensitive when wet.
History
Acetone peroxide was discovered in 1895 by Richard WolffensteinRichard Wolffenstein (chemist)
Richard Wolffenstein was a German chemist.He discovered acetone peroxide in 1895 by reacting acetone with hydrogen peroxide....
. He was the first chemist to use inorganic acids as catalysts. He was also the first researcher to receive a patent for using the peroxide as an explosive compound. In 1900 Bayer and Villiger described in the same journal the first synthesis of the dimer and also described use of acids for the synthesis of both peroxides. Information about these procedures including the relative proportions of monomer
Monomer
A monomer is an atom or a small molecule that may bind chemically to other monomers to form a polymer; the term "monomeric protein" may also be used to describe one of the proteins making up a multiprotein complex...
, dimer, and trimer is also available in an article by Milas and Golubović. Other sources include crystal
Crystal
A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...
structure and 3d analysis in The Chemistry of Peroxides edited by Saul Patai (pp. 396–7), as well as the Textbook of Practical Organic Chemistry by Vogel.
Chemistry
"Acetone peroxide" most commonly refers to the cyclicAlicyclic compound
An alicyclic compound is an organic compound that is both aliphatic and cyclic. They contain one or more all-carbon rings which may be either saturated or unsaturated, but do not have aromatic character...
trimer
Trimer (chemistry)
In chemistry, a trimer is a product derived from three identical precursors. Trimers are typically cyclic. Chemical compounds that often trimerise are aliphatic isocyanates and cyanic acids. Often, trimerization competes with polymerization....
TCAP (tri-cyclic acetone peroxide, or tri-cyclo, C
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
9H
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
18O
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...
6) obtained by a reaction between hydrogen peroxide
Hydrogen peroxide
Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...
and 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...
in an acid-catalyzed nucleophilic addition
Nucleophilic addition
In organic chemistry, a nucleophilic addition reaction is an addition reaction where in a chemical compound a π bond is removed by the creation of two new covalent bonds by the addition of a nucleophile....
. The dimer (C6H12O4) and open monomer
Monomer
A monomer is an atom or a small molecule that may bind chemically to other monomers to form a polymer; the term "monomeric protein" may also be used to describe one of the proteins making up a multiprotein complex...
are also formed, but under proper conditions the cyclic trimer is the primary product. A tetrameric
Oligomer
In chemistry, an oligomer is a molecule that consists of a few monomer units , in contrast to a polymer that, at least in principle, consists of an unlimited number of monomers. Dimers, trimers, and tetramers are oligomers. Many oils are oligomeric, such as liquid paraffin...
form was also described. In mildly acid
Acid
An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...
ic or neutral conditions, the reaction is much slower and produces more monomer
Monomer
A monomer is an atom or a small molecule that may bind chemically to other monomers to form a polymer; the term "monomeric protein" may also be used to describe one of the proteins making up a multiprotein complex...
ic organic peroxide
Organic peroxide
Organic peroxides are organic compounds containing the peroxide functional group . If the R' is hydrogen, the compound is called an organic hydroperoxide. Peresters have general structure RCOOR. The O-O bond easily breaks and forms free radicals of the form RO·...
than the reaction with a strong acid catalyst. Due to significant strain
Angle strain
Angle strain, also called Baeyer strain in cyclic molecules, is the resistance associated with bond angle compression or bond angle expansion. It occurs when bond angles deviate from the ideal bond angles to achieve maximum bond strength in a specific chemical conformation...
of the chemical bonds
Covalent bond
A covalent bond is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms. The stable balance of attractive and repulsive forces between atoms when they share electrons is known as covalent bonding....
in the dimer and especially the monomer, they are even more unstable than the trimer.
At room temperature, the trimeric form slowly sublimes
Sublimation (physics)
Sublimation is the process of transition of a substance from the solid phase to the gas phase without passing through an intermediate liquid phase...
, reforming as larger crystals of the same peroxide.
Acetone peroxide is notable as a high explosive not containing nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
. This is one reason why it has become popular with terrorists, as it can pass through scanners designed to detect nitrogenous explosives.
TCAP generally burns when ignited, unconfined, in quantities less than about 4 grams. More than 4 grams will usually detonate
Explosive material
An explosive material, also called an explosive, is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure...
when ignited; smaller quantities might detonate when even slightly confined. Completely dry TCAP is much more prone to detonation than the fresh product still wetted with water or acetone. The oxidation that occurs when burning is:
- 2 + 21 → 18 + 18
Theoretical examination of the explosive decomposition
Chemical decomposition
Chemical decomposition, analysis or breakdown is the separation of a chemical compound into elements or simpler compounds. It is sometimes defined as the exact opposite of a chemical synthesis. Chemical decomposition is often an undesired chemical reaction...
of TCAP, in contrast, predicts "formation of 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...
and ozone
Ozone
Ozone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...
as the main decomposition products and not the intuitively expected oxidation products." This result is in good agreement with the results of 60 years of the study of controlled decompositions in various organic peroxides. It is the rapid creation of gas from a solid that creates the explosion. Very little heat is created by the explosive decomposition of TCAP. Recent research describes TCAP decomposition as an entropic explosion
Entropic explosion
An entropic explosion is an explosion in which the reactants undergo a large change in volume without releasing a large amount of heat. The chemical decomposition of triacetone triperoxide or TATP is an example of an entropic explosion. It is not a thermochemically highly favored event...
.
The high sensitivity to shock, heat and friction are due to the instability
Instability
In numerous fields of study, the component of instability within a system is generally characterized by some of the outputs or internal states growing without bounds...
of the molecule
Molecule
A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...
. Big crystals, found in older mixtures, are more dangerous, as they are easier to shatter—and initiate—than small ones.
Due to the low cost and ease with which the precursors can be obtained, acetone peroxide can be manufactured by those without the resources needed to manufacture or buy more sophisticated explosives. When the reaction is carried out without proper equipment the risk of an accident is significant. Simply mixing sulfuric acid, hydrogen peroxide, and acetone can create the substance. Crystals of AP soon precipitate out.
There is a common myth that the only "safe" acetone peroxide is the trimer, made at low temperatures:
"The mixture must be kept below 10 degrees Celsius. If the crystals form at this temperature, it forms the isomer called tricycloacetone peroxide, which is relatively stable and safe to handle. If the crystals form above this temperature, the dimeric form, called dicycloacetone peroxide. This isomer is much more unstable, and could go off at the touch, making it not safe enough to be considered a practical explosive. As long as the temperature is kept below 10 degrees Celsius, then there is little to worry about."
The trimer is the more stable form, but is not much more stable than the dimer. All forms of acetone peroxide are sensitive to initiation
Initiation (chemistry)
In chemistry, initiation is a chemical reaction that triggers one or more secondary reactions. Often the initiation reaction generates a reactive intermediate from a stable molecule which is then involved in secondary reactions. In polymerisation, initiation is followed by a chain reaction and...
. Organic peroxides are sensitive, dangerous explosives; due to their sensitivity they are rarely used by well funded militaries. Even for those who synthesize explosives as a hobby there are far safer explosives with syntheses nearly as simple as that of acetone peroxide.
Acetone peroxide is commonly combined with 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...
by dissolving the nitrocellulose in acetone and then mixing in the acetone peroxide
Acetone peroxide
Acetone peroxide is an organic peroxide and a primary high explosive. It takes the form of a white crystalline powder with a distinctive bleach-like odor....
and letting it dry, this results in a mixture that is both more stable and somewhat more powerful than acetone peroxide by itself. This mixture is commonly referred to as APNC.
Tetrameric acetone peroxide is more chemically stable (heating to 120°C for 4 hours), but despite this, it is still a very dangerous primary explosive. It can be prepared using tin(IV) chloride
Tin(IV) chloride
Tin chloride, also known as tin tetrachloride or stannic chloride is a chemical compound with the formula SnCl4.At room temperature it is a colourless liquid, which fumes on contact with air, giving a stinging odor...
(without acid present) as a catalyst with up to 40% yield if radical
Radical (chemistry)
Radicals are atoms, molecules, or ions with unpaired electrons on an open shell configuration. Free radicals may have positive, negative, or zero charge...
inhibitor
Enzyme inhibitor
An enzyme inhibitor is a molecule that binds to enzymes and decreases their activity. Since blocking an enzyme's activity can kill a pathogen or correct a metabolic imbalance, many drugs are enzyme inhibitors. They are also used as herbicides and pesticides...
such as hydroquinone
Hydroquinone
Hydroquinone, also benzene-1,4-diol or quinol, is an aromatic organic compound that is a type of phenol, having the chemical formula C6H42. Its chemical structure, shown in the table at right, has two hydroxyl groups bonded to a benzene ring in a para position. It is a white granular solid...
, or a chelator such as EDTA
EDTA
Ethylenediaminetetraacetic acid, widely abbreviated as EDTA , is a polyamino carboxylic acid and a colourless, water-soluble solid. Its conjugate base is named ethylenediaminetetraacetate. It is widely used to dissolve limescale. Its usefulness arises because of its role as a hexadentate ligand...
is added.
It evaporates 6.5% in 24 h at 14–18°C. Openly at air at 25°C has a loss by sublimation of 68.6% in 14 days. Many accidents resulted from the fact that acetone peroxide detonates due to its sublimation characteristics within fewer days by crystallization in the range of the container cap, when opening the same. Keeping it wet stops the sublimation and can prevent this type of accident.
Industrial occurrence
Acetone peroxides are common and unwanted by-productBy-product
A by-product is a secondary product derived from a manufacturing process or chemical reaction. It is not the primary product or service being produced.A by-product can be useful and marketable or it can be considered waste....
s of oxidation reactions, such as those used in phenol
Phenol
Phenol, also known as carbolic acid, phenic acid, is an organic compound with the chemical formula C6H5OH. It is a white crystalline solid. The molecule consists of a phenyl , bonded to a hydroxyl group. It is produced on a large scale as a precursor to many materials and useful compounds...
syntheses. Due to their explosivity, they are hazardous. Numerous methods are used to reduce their production – shifting the pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
to more alkaline, adjusting the reaction temperature, or adding a soluble copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
(II) compound.
Acetone peroxide and benzoyl peroxide
Benzoyl peroxide
Benzoyl peroxide is an organic compound in the peroxide family. It consists of two benzoyl groups bridged by a peroxide link. Its structural formula is [C6H5C]2O2. It is one of the most important organic peroxides in terms of applications and the scale of its production...
are used as flour bleaching agent
Flour bleaching agent
Flour bleaching agent is a food additive added to flour in order to make it appear whiter and to oxidize the surfaces of the flour grains and help with developing of gluten.Usual bleaching agents are:...
s to bleach
Bleach
Bleach refers to a number of chemicals that remove color, whiten, or disinfect, often via oxidation. Common chemical bleaches include household chlorine bleach , lye, oxygen bleach , and bleaching powder...
and "mature" flour
Flour
Flour is a powder which is made by grinding cereal grains, other seeds or roots . It is the main ingredient of bread, which is a staple food for many cultures, making the availability of adequate supplies of flour a major economic and political issue at various times throughout history...
.
Ketone peroxides
Organic peroxide
Organic peroxides are organic compounds containing the peroxide functional group . If the R' is hydrogen, the compound is called an organic hydroperoxide. Peresters have general structure RCOOR. The O-O bond easily breaks and forms free radicals of the form RO·...
, including acetone peroxide, methyl ethyl ketone peroxide
Methyl ethyl ketone peroxide
Methyl ethyl ketone peroxide is an organic peroxide, a high explosive similar to acetone peroxide. MEKP is a colorless, oily liquid whereas acetone peroxide is a white powder at STP; MEKP is slightly less sensitive to shock and temperature, and more stable in storage.Dilute solutions of 30 to 60%...
, and benzoyl peroxide
Benzoyl peroxide
Benzoyl peroxide is an organic compound in the peroxide family. It consists of two benzoyl groups bridged by a peroxide link. Its structural formula is [C6H5C]2O2. It is one of the most important organic peroxides in terms of applications and the scale of its production...
, find applications as initiator
Radical initiator
In chemistry, radical initiators are substances that can produce radical species under mild conditions and promote radical reactions . These substances generally possess weak bonds—bonds that have small bond dissociation energies. Radical initiators are utilized in industrial processes such...
s for polymerization
Polymerization
In polymer chemistry, polymerization is a process of reacting monomer molecules together in a chemical reaction to form three-dimensional networks or polymer chains...
reactions of e.g. silicone
Silicone
Silicones are inert, synthetic compounds with a variety of forms and uses. Typically heat-resistant and rubber-like, they are used in sealants, adhesives, lubricants, medical applications , cookware, and insulation....
or polyester
Polyester
Polyester is a category of polymers which contain the ester functional group in their main chain. Although there are many polyesters, the term "polyester" as a specific material most commonly refers to polyethylene terephthalate...
resin
Resin
Resin in the most specific use of the term is a hydrocarbon secretion of many plants, particularly coniferous trees. Resins are valued for their chemical properties and associated uses, such as the production of varnishes, adhesives, and food glazing agents; as an important source of raw materials...
s, often encountered when making fiberglass
Fiberglass
Glass fiber is a material consisting of numerous extremely fine fibers of glass.Glassmakers throughout history have experimented with glass fibers, but mass manufacture of glass fiber was only made possible with the invention of finer machine tooling...
-reinforced composites. For these uses, the peroxides are typically in the form of a dilute solution in an organic solvent, though even commercial products with higher concentrations of organic peroxides can form crystals around the lid when older, making the can shock-sensitive. Methyl ethyl ketone is more common for this purpose, as it is stable in storage.
Accidental byproduct
Acetone peroxide can also occur accidentally, when suitable chemicals are mixed together, for example when methyl ethyl ketone peroxideMethyl ethyl ketone peroxide
Methyl ethyl ketone peroxide is an organic peroxide, a high explosive similar to acetone peroxide. MEKP is a colorless, oily liquid whereas acetone peroxide is a white powder at STP; MEKP is slightly less sensitive to shock and temperature, and more stable in storage.Dilute solutions of 30 to 60%...
is mixed with acetone while making fiberglass composites, and left to stand for some time, or when a mixture of peroxide and hydrochloric acid from printed circuit board
Printed circuit board
A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive substrate. It is also referred to as printed wiring board or etched wiring...
etching is mixed with waste acetone from cleaning the finished board and allowed to stand. While amounts obtained this way are typically much smaller than from intentional production, they are also less pure and prepared without cooling, and hence very unstable.
It is also a hazardous by-product of isosafrole
Isosafrole
Isosafrole is a phenylpropene, a type of aromatic organic chemical with a smell similar to anise or licorice. It is found in small amounts in various essential oils, but is most commonly obtained by isomerizing the plant oil safrole....
oxidation in acetone, a step in the synthesis of MDMA.