Discussion

The reaction of acetone and hydrogen peroxide in the presence of HCl is exothermic and spontaneous, forming peroxyacetone (CH₃C(OOH)₂CH₃), a white crystalline substance that is heat and shock sensitive.

Peroxyacetone is a powerful explosive that provides its own oxygen, and its own reducing agent in the form of carbon and hydrogen. When peroxyacetone is ignited, the flame expands to about 10 times the volume of the original solid. Shakhashiri (1) reports that peroxyacetone often undergoes decomposition to form 2,2-dihydroperoxydiisopropyl peroxide, and in an excess of acetone, converts into the cyclic trimer 1,1,4,4,7,7-hexamethyl-1,4,7-cyclononatriperoxane in high yield. This heterocyclic organic molecule is highly unstable. If completely consumed, it releases approximately 5700 kJ/mol.

In this demonstration, the reaction is initiated with 10,000 V arc, at 23 mA. The solid is piled loosely onto an iron surface, and the arc wire is placed about 2 cm above the pile of peroxyacetone solid. The switch is thrown to initiate the arc, and the reaction occurs immediately, resulting in a ball of flaming orange-red gas about 1 meter in diameter, along with a muffled report.