Safety: Dangers Of Diglyme
Reading the investigators=E2=80=99 account of the T2 Laboratories
explosion, which was attributed to metallic sodium and hot di glyme, 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=E2=80=99s Handbook of Reactive Chemical Hazards,=E2=80
=9D but, having its primary entry under "lithium aluminium
hydride,=" might be missed by the hasty searcher.
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 =C2=B0C.
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
Capping the glycol as an ether, so that
methanol, or dimethyl ether, is eliminated rather than water, will do
little to the thermodynamics=E2=80=94and perhaps not much to the
kinetics=E2=80=94of reaction. The simplest diethyleneglycol ether,
dioxan, is known to decompose exothermically at around 200 =C2=B0C.
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