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 (not much energy generated in chemical bond formation in reaction products). It rather involves an entropy burst, which is the result of formation of one ozone and three acetone gas phase molecules from every molecule of TATP in the solid state.

External links and references

• Dubnikova, F.; Kosloff, R.; Almog, J.; Zeiri, Y.; Boese, R.; Itzhaky, H.; Alt, A.; Keinan, E.; J. Am. Chem. Soc.; (Article); 2005; 127(4); 1146-1159.
• The Skaggs Institute for Chemical Biology 2004 "The calculated thermal decomposition pathway of the TATP molecule was a complicated multistep process with several highly reactive intermediates, including singlet molecular oxygen and various biradicals. Of note, the calculations predict formation of acetone and ozone as the main decomposition products and not the intuitively expected oxidation products. The key conclusion from this study is that the explosion of TATP is not a thermochemically highly favored event. Rather, the explosion involves entropy burst, which is the result of formation of 4 gas-phase molecules from every molecule of TATP in the solid state. Quite unexpectedly, the 3 isopropylidene units of the TATP molecule do not play the role of fuel that can be oxidized and release energy during the explosion. Instead, these units function as molecular scaffolds that hold the 3 peroxide units close together spatially in the appropriate orientation for the decomposition chain reaction."
• Israeli Invention Detects TATP Explosives "To our great surprise,” PET’s inventor, Prof. Ehud Keinan, Dean of the Technion's Faculty of Chemistry, wrote in the Journal of the American Chemical Society, “we discovered that TATP is very different from all other conventional explosives in that it does not release heat during the explosion. It explodes by rapid decomposition of every solid-state molecule to four gas-phase molecules. This rare phenomenon, scientifically known as 'Entropic Explosion', is reminiscent of the rapid reaction that produces gas in the safety air-bags of cars during accidents."
• Chemical and Engineering News PDF