Acetone peroxide
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| 3,3,6,6-tetramethyl-1,2,4,5-tetraoxane (dimer) 3,3,6,6,9,9-hexamethyl-1,2,4, 5,7,8-hexaoxacyclononane (trimer) IUPAC name | |
| Chemical formula | C6H12O4 (dimer) C9H18O6 (trimer) |
| Molecular mass | 148.157 g/mol (dimer) 222.24 g/mol (trimer) |
| Shock sensitivity | High |
| Friction sensitivity | High |
| Density | 1.18 g/cm3 |
| Explosive velocity | 5300 m/s |
| RE factor | ? |
| Melting point | 91 °C |
| Autoignition temperature | Unknown |
| Appearance | White crystalline solid |
| CAS number | 17088-37-8 |
| PubChem | 536100 |
| SMILES | CC1(C)OOC(C)(C)OOC(C)(C)OO1 CC1(C)OOC(C)(C)OO1 |
Acetone peroxide (triacetone triperoxide, peroxyacetone, TATP, TCAP) is an organic peroxide and a primary high explosive. It takes the form of a white crystalline powder with a distinctive acrid smell.
It is highly heat, friction, and shock sensitive. For its instability, it has been called the "Mother of Satan". It has perhaps sprung into notoriety due to its use in the July 2005 London bombings.
Acetone peroxide was discovered in 1895 by R. Wolffenstein (Chemische Berichte 28, 2265 (1895)). Information about it including the relative proportions of monomer, dimer, and trimer is also available in the Journal of the American Chemical Society 81, 6461 (1959). 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.
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Chemistry
Also known as "peroxyacetone", acetone peroxide most commonly refers to the cyclic trimer TCAP (tri-cyclic acetone peroxide, or tri-cyclo), also called triacetone triperoxide (TATP), obtained by mixing hydrogen peroxide with acetone using a small amount of acid (mentioned above) as a catalyst. The cyclic dimer (C6H12O4) and open monomer and dimer are also formed, but under proper conditions the cyclic trimer is the primary product. A tetrameric form was also described. In mildly acidic or neutral conditions, the reaction is much slower and produces more monomeric 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 sublimates, reforming as the less stable, more sensitive dimer.
TCAP generally burns when ignited, unconfined, in quantities less than about 2 grams. More than 2 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:
The explosive decomposition of TCAP, in contrast, results in "formation of acetone and ozone as the main decomposition products and not the intuitively expected oxidation products." [1] 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 extreme shock, heat, and friction sensitivity 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.
Many people have been killed or permanently injured by accidents with acetone peroxide. It is widely used by people who want to make homemade explosives because of its low cost and ease of manufacture. They often have no idea of its extreme sensitivity, or they make it anyway solely because it's cheap and can be made in a refrigerator. There is a common myth that the only "safe" acetone peroxide is the trimer, made at low temperatures: "If one is making tricycloacetone peroxide, the temperature must be less than 10 °C at all times, otherwise the product formed will be dicycloacetone peroxide, which is so unstable and sensitive that it has no uses in the field of explosives: dicycloacetone peroxide has been known to explode spontaneously." In reality, the acid-catalyzed peroxidation of acetone always produces a mixture of dimeric and trimeric forms. The trimer is the more stable form, but not much more so than the dimer. All forms of acetone peroxide are very sensitive to initiation. Organic peroxides are sensitive, dangerous explosives. The military does not use them because there are many much better alternatives. Even for people who synthesize homemade explosives, there are many far safer alternatives. Even nitroglycerin is not nearly as sensitive as acetone peroxide.
Industrial occurrence
Acetone peroxides are common and unwanted by-products of oxidate reactions, eg. 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. Destruction of acetone peroxide patent
Acetone peroxide and benzoyl peroxide are used as flour bleaching agents to bleach and "mature" flour.
Ketone peroxides, including acetone peroxide, methyl ethyl ketone peroxide, and benzoyl peroxide, find applications as initiators for polymerization reactions of eg. silicone or polyester resins, often encountered when making fiberglass. For these uses, the peroxides are typically in the form of a dilute solution in an organic solvent, however, 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, however, 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 is mixed with acetone when making fiberglass, and left to stand for some time, or when a mixture of peroxide and hydrochloric acid from printed circuit board etching (the FeCl3 method is less smelly, more accurate, but slower) 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 illicit synthesis of MDMA.
Terrorism
It is believed that Acetone peroxide was used as the explosive in the 7 July 2005 London bombings.[2]
