Inadvertent synthesis of triacetone triperoxide (TATP)
May03

Inadvertent synthesis of triacetone triperoxide (TATP)

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° 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° 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, τ = 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...

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Report on U Hawaii explosion delayed until late May
Apr28

Report on U Hawaii explosion delayed until late May

From the University of Hawaii regarding the March explosion that caused a postdoctoral researcher to lose one of her arms. UH retained the University of California Center for Laboratory Safety to investigate the incident, and that report was expected this week. The independent investigation into the March 16, 2016 explosion in a University of Hawaiʻi at Mānoa laboratory is now expected to be complete in mid to late May. It was initially expected to finish by the end of April. The University of California Center for Laboratory Safety, retained by UH to conduct the investigation, was unable to send materials involved in the explosion for testing until the Hawaiʻi State Occupational Safety and Health Division (HIOSH), the government agency investigating the accident, completed its review of the accident scene. HIOSH released the materials and scene to UH late last week. … In its preliminary investigation, the UC Center for Laboratory Safety, considered a national leader in laboratory safety, determined that the explosion was an isolated incident and not the result of a systemic...

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For polycoordinated iodine species, use triflate as a counterion
Apr27

For polycoordinated iodine species, use triflate as a counterion

An inquiry from a reader got me to look up these two safety letters from 1989, and I thought I’d post them in case they’re useful to anyone working with iodine compounds now: Iodosobenzene salt explosion (July 24, 1989, page 2): Iodosobenzene tetrafluoroborate was described in 1988 by V. V. Zhdankin et al. [Tetrahedron Lett., 29, 3717 (1988)] as the first stable hypervalent iodine reagent without a nucleophilic ligand. After having prepared a few grams of the product according to the protocol in the cited literature without any difficulties, we decided to undertake a 0.5 mol preparation in the same manner. After drying the yellow crude product (about 75 g) in vacuo at room temperature for about 20 hours, it exploded while still in the flask in vacuo, producing a considerable amount of pungent fumes. The blast from the explosion was such that fragments of the flask penetrated glassware standing nearby as well as a security shield located in front of the flask. Fortunately, no one was in the laboratory at the time of the explosion. We are unable to say whether the explosion was caused by impurities or by the instability of the product itself. However we would like to warn anyone preparing or handling iodosobenzene tetrafluoroborate to be extremely careful. Gert van Look Fluka Chemie A.G. Buchs, Switzerland Iodonium salt explosions (Aug. 21, 1989, page 4): The current renaissance in polycoordinate iodine chemistry and in particular iodonium salt species, along with the recent report by G. v. Look (C&EN, July 24, page 2) on the explosion of iodosobenzene tetrafluoroborate, prompts us to report our own experiences with these compounds. We have also had an explosion (fortunately with no injury and only very minor damage) in the attempted preparation of an iodonium perchlorate, specifically PhC≡C—I+—Ph•ClO4–. In contrast, we have prepared numerous, diverse iodonium triflates and tosylates (up to 25 g scale), including PhC≡C—I+—Ph•–OTf(–OTs), and to date experienced no difficulties in the formation, handling, and subsequent transformations of these salts. It is generally recognized that perchlorates tend to be explosive, whereas fluoroborates are much less explosive, and triflates are considered even more stable. Hence, we suggest the substitution of triflate (CF3SO3–) for ClO4– in all cases where a nonnucleophilic counterion is desired and perhaps even in some cases as substitution for BF4–. Even with triflates, ordinary caution should be exercised in the handling of all potentially explosive compounds—including the above and related polycoordinated iodine species. Peter J. Stang Professor of Chemistry University of...

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“We felt the explosion rattle the floor and walls eight floors up…”
Apr26

“We felt the explosion rattle the floor and walls eight floors up…”

We’ve had a lot of comments at C&EN about my story, “Spark from pressure gauge caused University of Hawaii explosion, fire department says.” I thought I’d flag a few of them here: I am a researcher in the same building as the HNEI, although not on the same floor, and not in the same field. We felt the explosion rattle the floor and walls eight floors up – Dr. Ekins-Coward is truly lucky to be alive. The incident has prompted campus-wide laboratory safety re-certification efforts here, particularly with regard to pressurized gas cylinders, whether or not they contain flammable gases. PIs, please take the time to discuss with your lab staff and students proper gas handling – students and staff, if you see red flags, don’t let up until your PI fixes the issue. It really sucks having something like this happen in your University, let alone your own lab building and community. — I can empathize with this researcher…. I work with Hydrogen, CO, and O2 in the lab and did not consider the issue with fires…. I will conduct a SAP review and modify our current working conditions. I teach a safety course and work closely with SAChE but and aware of the LFL and UFL of H2… we as researchers get tunnel vision. I am very sorry it took someone to lose an arm for me to realize the danger I put myself and my researcher at…. I know better. — Where I work, an experiment of this type would never be allowed to become operational until a subject matter expert (or probably a team of them, in this case) fully inspected the design and the operating parameters. Especially if the system was built by a new member of a research team. A full hazard control plan, in writing, would be written up and signed off by anyone touching the experiment. In my world, the subject matter experts are drawn from research scientists familiar with the experimental designs. Since it was a pressurized system containing an explosive hydrogen gas mixture, I suspect that at minimum, there would be an emphasis on a design that minimized risk including volume limits, an inspection for electrical safety, and likely, some sort of containment system would be incorporated to protect against just this sort of catastrophe. A reviewer would probably ask “is there a safer way to introduce the gas mixture into the reactor?”. These sorts of intensive safety programs add time and cost to the business of doing science (but are ubiquitous in industry and government labs), but the flip side is what we see in these pictures: when...

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U Hawaii story now has photos
Apr22

U Hawaii story now has photos

Just a quick FYI to Safety Zone readers to note that my U Hawaii story from earlier this week, “Spark from pressure gauge caused University of Hawaii explosion, fire department says,” now has photos provided by the Honolulu Fire Department.

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