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.
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 a reaction between hydrogen peroxide and acetone (using 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 sublimes, 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:
2 C9H18O6 + 21 O2 → 18 H2O + 18 CO2 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."[2] 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 may be unaware of its extreme sensitivity; or they make it anyway because it is 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." [citation needed] 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.