Via C&EN's letters to the editor this week, some 1970s-era safety letters regarding inadvertent synthesis of triacetone triperoxide (TATP):

Violent explosion (Feb. 21, 1977, page 5):

While making 6-amino-penicillanic acid S-oxide, there was an explosion in our laboratory, at which time one man was injured.. The cause of the accident has been found to be trimeric acetone peroxide.

For the experiment in question we used 1 mole of 6-APA. It was oxidized according to the instructions published in "Synthesis" 1976, page 264, and precipitated as p-toluene sulfonate in the presence of acetone. 130 grams (0.32 mole) of the product was treated with triethylamine in isopropanol according to the instructions. The precipitate was filtered with suction on a glass sinter, washed with acetone, and air was allowed to flow through the filter cake.

When the technician who was performing the experiment took the sinter in his hand and touched the precipitate with a steel spatula, it exploded violently. The technician received severe burns and splinter wounds in his eyes, hands, and body. Two windows were broken and there were holes in the glass of a fume cupboard at 3 m distance. The surface of the work table was spoiled.

The explosive substance was found to be trimeric acetone peroxide. It was isolated from the mother liquor, from which it crystallized as large crystals. The melting point of the substance was 97 =B0 C. In literature ["Encyclopedia of Explosives and Related Items," Vol. 1, Basil T. Fedoroff, Picatinny Arsenal, Dover, N.J. (1960)] the melting range is given at 94 to 98.5 =B0 C. The infrared spectrum was identified with the aid of a computer, and it was identical with the spectrum in the Sadtler catalog. On the basis of the NMR spectrum it was established to contain only one type of protons, =CF=84 = 8.5.

The explosion of trimeric acetone peroxide was probably caused by the combined effect of static energy and friction. The static energy accumulated in man can be 30 mJ. We performed different sensitivity tests with the isolated substance. It exploded moist with an 11.5-mJ electric spark. In impact sensitivity tests, it ignited repeatedly with a weight of 2 kg from 10 cm's height. In friction sensitivity tests, the sample ignited with a weight of 0.5 kg. The ignition sensitivity increased when the substance was dried.

Trimeric acetone peroxide was the only explosive compound that we were able to isolate from the mother liquor that was spared. Thus we have every reason to believe that just this substance caused the accident. According to literature, acetone peroxide is easily produced from acetone and hydrogen peroxide catalyzed by an acid.

A. Noponen
R&D Director, Fermion Oy, Tapiola, Finland

Potential explosion forewarned (May 23, 1977, page 4):

We are preparing R- and S-pentobarbital which requires the ozonolysis of R- and S-citronellic acids. Wolff-Kishner (Huang-Minion) reduction of the resulting citronellals yielded an unwanted product, melting point 95 =B0, and with single proton peak on the NMR spectrum at 1.48=CE=B4. Gerald Lillquist of 3M Co. with the aid of a computer identified its infrared spectrum as that of trimeric acetone peroxide. By a rare coincidence, a few days later C&EN carried a report of a violent explosion in Finland caused by the identical compound (C&EN, Feb. 21, page 5).

In our experiment we ozonized citronellic acid (0.29 mole) dissolved in methylene chloride and immersed in a dry-ice acetone bath. Dimethyl sulfide (50 ml) was added to decompose the presumed ozonide. The mixture was allowed to come to room temperature, and it was then concentrated at reduced pressure. Hydrazine in glycol was added to the residue, followed by potassium hydroxide. The mixture was then heated to 200 =B0C. The triacetone peroxide distilled in respectable yield through a short, aircooled condenser between 105 =B0 and 135 =B0C. Hydrazine (and water) codistilled with the peroxide which thus remained as a suspension of large crystals. The suspension was disposed of by pouring it carefully into a large volume of cold, acidified aqueous solution of potassium iodide.

It is conceivable that during ozonolysis of any isopropylidene group triacetone peroxide is formed. Presumably it originates from the rearrangement of the (mol)ozonide. Consequently, appropriate care is advised.

Yul Yost