- An explosive sometimes used by terrorists does not burn
when it detonates. Instead, its molecules simply fall apart. The chemist
who has discovered this is so concerned by its implications that he has
decided to abandon this line of research.
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- Triacetone triperoxide (TATP) has been used by suicide
bombers in Israel and was chosen as a detonator in 2001 by the thwarted
"shoe bomber" Richard Reid. Now calculations by Ehud Keinan from
the Technion-Israel Institute of Technology in Haifa show that most of
its explosive force comes from a rapid release of gas rather than a burst
of energy.
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- In conventional high explosives such as TNT, each molecule
contains both a fuel component and an oxidising component. When the explosive
detonates, the fuel part is oxidised and as this combustion reaction spreads
it releases large amounts of heat almost instantaneously.
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- TATP molecules are made up of fragments that could react
in a similar way. But Keinan says that videos showing samples of TATP being
detonated show that it can do so without producing any flame.
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- Oxygen and ozone
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- His team's calculations indicate why. Explosions are
driven by the reaction that takes the least energy to start. In this case
it is not oxidation but disintegration. The TATP molecule sheds acetone
units, setting free the oxygen atoms that bound them together to form the
gases oxygen and ozone. It also releases just enough energy to spread the
reaction to the next molecule.
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- One molecule of TATP produces four of gas, giving TATP
its explosive power. Just a few hundred grams of the material will produce
hundreds of litres of gas in a fraction of a second.
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- "It's different to conventional explosives,"
agrees Jimmie Oxley, a chemist at the University of Rhode Island in Kingston,
US, who has studied TATP and worked with Keinan on other projects. But
it is not unique. The decomposition of azide, for example, which produces
nitrogen gas but little heat, is used to fill airbags for cars.
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- TATP turns out to be the most extreme example so far,
and it may be possible to design molecules that behave as an even more
powerful explosive. But the idea does not appeal to Keinan. "I don't
want to continue this kind of research," he says. Instead, he plans
to work with security agencies to develop a device that can detect TATP.
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- - Journal reference: Journal of the American Chemical
Society (DOI: 10.1021/ja0464903)
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- © Copyright Reed Business Information Ltd.
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- http://www.newscientist.com/article.ns?id=dn6925
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