From: DCHAS Membership Chair <membership**At_Symbol_Here**DCHAS.ORG>
Subject: [DCHAS-L] C&EN article: Chemists continue to forget safety concerns about sodium hydride
Date: Tue, 20 Aug 2019 07:36:01 -0400
Reply-To: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**PRINCETON.EDU>
Message-ID: DEFF2541-EB84-4DFA-99FF-22CAD8F396EC**At_Symbol_Here**

Chemists continue to forget safety concerns about sodium hydride

Popular base can decompose certain solvents, potentially leading to explosions

A recent report is bringing chemists‰?? attention to a longstanding but frequently forgotten hazard in chemistry. Sodium hydride (NaH), when used with certain solvents, can unexpectedly generate heat and gas, leading to a runaway reaction or even an explosion (Org. Process Res. Dev. 2019, DOI: 10.1021/acs.oprd.9b00276).

Synthetic chemists often use NaH to pluck protons from molecules. But to get this ionic base into solution with greasy organic molecules, chemists usually have to use a so-called polar aprotic solvent, such as dimethylsulfoxide (DMSO), dimethylformamide (DMF), or dimethylacetamide (DMAc).

Reports that NaH in these solvents can lead to explosions date back more than 50 years, says Qiang Yang, a chemist with Corteva Agriscience who led the team behind the report. Nevertheless, he says, every year chemists publish papers that describe the use of these unsafe combinations. Yang‰??s team reports that between 2014 and 2018, Organic Letters published 38‰??62 papers/year with these combinations, the Journal of Organic Chemistry published 28‰??46 papers/year, and the Journal of Medicinal Chemistry published 67‰??94 papers/year.

‰??The most striking feature of this paper is the authors‰?? data compilation showing the abundance of recent papers that continue to use these hazardous reagent combinations,‰?? says Suzanne Blum, a chemist at the University of California, Irvine.

(more at URL above)...

Ralph Stuart, CIH, CCHO

Membership chair
American Chemical Society
Division of Chemical Health and Safety

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