More discussion on the U Minnesota azide explosion
Nov18

More discussion on the U Minnesota azide explosion

We’ve had blog post the first (“Explosion injures…”) and blog post the second (“More details…”), plus a C&EN safety letter and “C&EN Talks Safety with William B. Tolman.” A reader responds in this week’s issue: I was disappointed by the lengthy chemical safety letter from T. Andrew Taton and Walter E. Partlo on the azidotrimethylsilane explosion in Taton’s lab (C&EN, Oct. 27, page 2). Lacking was the admission that Partlo, a fifth-year graduate student, was not wearing any personal protection at the time of the incident. Their concluding recommendations also omit any mention of having used personal protective equipment. Where is the recommendation for the use of a blast shield? A blast shield provides an additional layer of protection for the researcher when the hood is opened, especially in cases where the hood is not the vertical multi-sliding-door type but the full horizontal sash type. (See the University of Illinois webpage at https://www.drs.illinois.edu/Resources/PotentiallyExplosiveExperiments.) I have never forgotten a coworker’s serious injuries in a Yale University chemistry lab in the 1970s during the distillation of a mere 25 mL of a known hazardous compound. Why do our academic labs still not take basic precautions when working with such hazards? Why isn’t personal protection the basic standard at all times in our chemistry research labs? I reference C&EN’s The Safety Zone blog: “He stopped and reached into the hood, but he didn’t have time to touch anything before the experiment exploded, says Anna Sitek, a research safety specialist in UMN’s department of environmental health and safety. Partlo wasn’t wearing any personal protective equipment.” Katherine E. Flynn St. Charles, Ill. While Flynn has a point about the fact that basic personal protective equipment should be standard, it’s worth remembering that PPE comes last on the hierarchy of controls, after elimination, substitution, engineering, and administrative. Both the safety letter and my discussion with Tolman were focused more on those higher-level controls. Also, over at Chemjobber is some more information about the department’s 5 g limit for reactions involving azide. Last but not least, the Campus Safety Health & Environment Management Association is holding a webinar on Dec. 3 to discuss hazard evaluation and communicating lessons learned featuring Minnesota chemistry department chair William Tolman, safety officer Anna Sitek, and chemical hygiene officer Jodi Ogilvie. It’s free for CSHEMA members, $130 for...

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More details on the University of Minnesota explosion and response
Jul30

More details on the University of Minnesota explosion and response

On June 17, an explosion in a chemistry lab at the University of Minnesota injured graduate student Walter Partlo. He was making trimethylsilyl azide, starting with 200 g of sodium azide. The incident originated in lack of hazard awareness, school representatives say, and the department response focuses on identifying hazardous processes and communication. The synthesis was based on previously published methods, with some alterations—in particular, the solvent Partlo used was polyethylene glycol (PEG), says chemistry department chair William B. Tolman. Partlo is a fifth-year graduate student in professor T. Andrew Taton’s group, which had run the reaction at least ten times previously, Tolman says. When the explosion happened, the reaction was on its second day. Partlo was on his way from the lab office to the hall when he noticed that the thermometer was askew. He stopped and reached into the hood, but he didn’t have time to touch anything before the experiment exploded, says Anna Sitek, a research safety specialist in UMN’s department of environmental health and safety. Partlo wasn’t wearing any personal protective equipment. The explosion left him with second-degree burns and glass injuries to his arm and side; he also injured an eardrum. The explosion also destroyed the experimental apparatus and hood. Tolman, Sitek, and other investigators have not been able to definitively identify what went wrong with the reaction, Tolman says. One explanation is that the explosion was from hydrazoic acid, which could have formed from wet PEG providing water to react with sodium azide or the PEG itself reacting with sodium azide. Another explanation is that the sodium azide overheated. More important than the reaction, Tolman emphasizes, is the deeper root cause of the incident: insufficient recognition of the reaction’s hazards. Warnings included with literature protocols were “pretty lame,” he says. He also thinks that the lab group became became complacent after doing the reaction several times without incident. “While they were aware of the hazards, concern about them became less up front,” he says. Also, as people modified the protocol, they didn’t appear to understand how changes might affect the risk of the synthesis. “There was a real reason to use PEG,” Tolman says. The reaction involved a heterogeneous mixture and people had trouble with clumping, and literature indicated that using PEG would help. “But they hadn’t thought through that maybe the PEG was wet or might react itself,” Tolman says. “It was not a case of blowing off safety,” Sitek adds. “They thought they were making the right changes, but they didn’t know the questions to ask to recognize when they were moving in the wrong direction.” “Overall, there was clearly a...

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Explosion injures University of Minnesota graduate student
Jun19

Explosion injures University of Minnesota graduate student

An explosion on Tuesday in a chemistry lab at the University of Minnesota injured a graduate student. The student was making trimethylsilyl azide. The student injured his arm and side, and he needed surgery to deal with glass shards, chemistry department chair William B. Tolman said yesterday afternoon. The student also injured an eardrum. He was not severely burned. “He was lucky,” Tolman said. “It was a pretty powerful explosion.” Tolman expected the student to be hospitalized for another couple of days. The procedure that the student was following was from Org. Synth. 1970, DOI: 10.15227/orgsyn.050.0107. He’s a member of professor T. Andrew Taton‘s group. Investigators have not spoken with the student yet, and they don’t know how much material he was working with or at what point he was at in the process, Tolman said. The location of the student’s injuries indicates that he was reaching into the hood when the explosion happened, but what he was reaching for or why remains unknown. Tolman also didn’t know what protective equipment the student was wearing or whether he was using a blast shield. As for why the explosion happened, “I have a lot of ideas and no evidence for any one of them,” Tolman said. Humid weather could have led to moisture in the system and production of hydrazoic acid, for example, or something could have set off the sodium azide starting material. “I have concerns over the level of recognition of hazard and risk mitigation, but I don’t know enough yet about what exactly was done and not done,” Tolman said. The department has been working over the past couple of years to improve its safety culture. Given all the unknowns about the incident, it’s too early to say whether the efforts helped to mitigate what happened or what more the department might want to do, Tolman said. At the same time, “I will say that we are in a particularly good position to learn well because we already have a strong communications effort in place,” he added. People working with organic azides should refer to “Organic Azides, Syntheses and Applications” by Stefan Bräse and Klaus Banert for safety precautions. More discussion at Chemjobber Updated to add photo Updated again to add: More details on the University of Minnesota explosion and...

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