31.11 What is Sarin nerve gas?
Description
This article is from the Chemistry FAQ, by Bruce Hamilton B.Hamilton@irl.cri.nz with numerous contributions by others.
31.11 What is Sarin nerve gas?
Sarin is a nerve gas that was used in 1988 by Iraq against its Kurdish
population, and in 1995 by Japanese terrorists against Tokyo subway users.
Sarin and its companion nerve gases ( Tabun and Soman ) were discovered
in the late 1930s by Gerhard Schrader at I.G.Farben during research into
pesticides. The lethal dose for humans may be as low as 0.01mg/kg [18],
unless treated immediately. Sarin inhibits acetylcholinesterase, an enzyme
that breaks down acetylcholine. Acetylcholine carries signals between nerves
and muscles, and build-up causes over-stimulation of muscles ( including
the involuntary ones controlling eye, lungs, bowel ), which then go into
spasms. Treatment involves atropine ( shuts down the overstimulated nerves ),
or oxime drugs ( can prise Sarin off the enzyme ), and must be immediate.
More details and references can be found in the Merck Index.
There are many different methods of manufacture, but the Tokyo product
appears to have been prepared using a procedure involving phosphorus
trichloride and methyl iodide. The product was impure and diluted with
acetonitrile to improve volatility. To stockpile Sarin, the product has to
be pure ( 90-99% of the Iraqi Sarin degraded in < 2 years, whereas US Sarin
only degraded a few % over 30 years ). The standard US government procedure
( aka "di-di" ) starts with dimethyl methylphosphonate (DMMP), and ends
with a distillation to remove impurities [19].
O O O O CH3
|| thionyl || HF || isopropyl || /
CH3-P-OCH3 ------> CH3-P-Cl --> CH3-P-F ---------> CH3-P-O-CH
| chloride | | alcohol | \
OCH3 Cl F F CH3
DMPP Dichlor Difluor Sarin (GB)
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