Acetone peroxide
Chemical name	3,3,6,6,9,9- hexamethyl- 1,2,4,5,7,8- hexaoxacyclononane
Chemical formula	C9H18O6
Molecular mass	222.24 g/mol
Shock sensitivity	0.3NM
Friction sensitivity	unknown, possibly as low as .1NM
CAS number	17088-37-8

Acetone peroxide is a high explosive that can be made from common household items: drain cleaner (sulfuric acid), hydrogen peroxide, and acetone. Since its precursors are readily available, it is commonly used by amateur bomb makers, often for detonators, and is sometimes used in terrorist attacks. Other strong acids such as hydrochloric acid may also be used to catalyze the reaction.

Warning: Acetone peroxide is highly heat, friction, and shock sensitive . Even professional chemists have been injured attempting to use it.

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, 6261 (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.

Chemistry

Also known as "peroxyacetone," acetone peroxide most commonly refers to the cyclic trimer TCAP (tri-cyclic acetone peroxide, or tri-cyclo), 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. In mildly acidic or neutral conditions, the reaction is much slower and produces more monomeric peroxide than the reaction with a strong acid catalyst.

TCAP generally burns when ignited, unconfined, in quantities less than about 2 grams. Above this, it will usually detonate, although even slight confinement will promote detonation in smaller quantities. Completely dry TCAP is much more prone to detonation as opposed to fresh product still wetted with water or acetone. The oxidation that occurs when burning is:

2 C₉H₁₈O₆ + 21 O₂ → 18 H₂O + 18 CO₂

The extreme shock, heat, and friction sensitivity are due to the instability of the molecule. Like all energetic materials, TCAP releases energy upon initiation because the products formed by disintegration and recombination of its molecular components are more stable than the original molecule. Obviously the following analogy is only partially accurate, but imagine TCAP as a tall stack of blocks. When one block is knocked out, the whole pile falls over because the initial stack of blocks is unstable compared to a jumbled heap of the same blocks. If the block stacks (or molecules) are close together, the released energy causes neighboring molecules to fall apart also in a chain reaction. When this reaction propagates supersonically, TCAP detonates. Recent research describes TCAP decomposition as an entropic explosion

Many people have been killed or permanently injured by accidents with acetone peroxide. 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 greatly more so than the dimer. All forms of acetone peroxide are very sensitive to initiation and degrade in long-term storage, so they are used as explosives only by terrorists and curious amateurs. At the same time, no form of acetone peroxide will truly explode spontaneously.

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