July 12, 2010 - Volume 88, Number 28
- p. 4
Letters
Latest News
October 28, 2011
Speedy Homemade-Explosive Detector
Forensic Chemistry: A new method could increase the number of explosives detected by airport screeners.
Solar Panel Makers Cry Foul
Trade: U.S. companies complain of market dumping by China.
Novartis To Cut 2,000 Jobs
Layoffs follow similar moves by Amgen, AstraZeneca.
Nations Break Impasse On Waste
Environment: Ban to halt export of hazardous waste to developing world.
New Leader For Lawrence Livermore
Penrose (Parney) Albright will direct DOE national lab.
Hair Reveals Source Of People's Exposure To Mercury
Toxic Exposure: Mercury isotopes in human hair illuminate dietary and industrial sources.
Why The Long Fat?
Cancer Biochemistry: Mass spectrometry follows the metabolism of very long fatty acids in cancer cells.
Chemical Safety: Dangers Of Diglyme
Reading the investigators’ account of the T2 Laboratories explosion, which was attributed to metallic sodium and hot diglyme, we suspect this may be an example of a much wider phenomenon, already met in other guises (C&EN, Sept. 21, 2009, page 8). A previous account of a violent runaway in diglyme, postulated as powered by reaction with finely divided active metal (in this case aluminum) has long been in “Bretherick’s Handbook of Reactive Chemical Hazards,” but, having its primary entry under “lithium aluminium hydride,” might be missed by the hasty searcher.
We are also strongly reminded of the Seveso, Italy, accident of 1976 (and its several precursors). Investigation showed that these were the result of a high-temperature, base-induced decomposition of diethylene glycol, or ethylene glycol itself, to materials including hydrogen and water, the coreagent sodium hydroxide, not sodium metal, and the temperature again around 200 °C.
Thermodynamic calculations from “Heats of Formation” suggest that 1,2 diols are higher energy than they look and may dehydrate exothermically. This, no doubt, is why biology finds sugars so useful as fuels and energy stores (and why sugar refineries occasionally have explosions from a hot molasses decomposition usually attributed to Maillard reaction with protein impurities).
Capping the glycol as an ether, so that methanol, or dimethyl ether, is eliminated rather than water, will do little to the thermodynamics—and perhaps not much to the kinetics—of reaction. The simplest diethyleneglycol ether, dioxan, is known to decompose exothermically at around 200 °C.
Martin J. Pitt
Assistant Editor, Bretherick’s Handbook
Chemical & Process Engineering, University of Sheffield
Sheffield, U.K.
Peter G. Urben
Editor, Bretherick’s Handbook
Kenilworth, U.K.
- Chemical & Engineering News
- ISSN 0009-2347
- Copyright © 2011 American Chemical Society
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