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I'm studying organic chemistry, and I noticed that there are fluoro-, chloro-, bromo-, and iodoalkanes. However, there are none for Astatine. Could someone shed some light on this, and what it would be called?

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    $\begingroup$ Astatine is so unstable that for most chemical purposes you may just as well consider it non-existent. $\endgroup$ – Ivan Neretin May 28 '17 at 15:05
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    $\begingroup$ The fact that you're unlikely to come across an organoastatine compound doesn't make the question unimportant or uninteresting; astatine derivatives have definitely been made, and there are certainly naming conventions. $\endgroup$ – JSK May 28 '17 at 15:37
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Part of the reason why there has been very little research done on organoastatine chemistry is the extreme radioactivity of astatine; the half-life of $\ce{^210At}$, the longest-lived isotope, is about 8 hours. However, the element can be incorporated into organic compounds (e.g., via a destannylation reaction).1

In organic chemistry, the prefix is "astato-", as in astatobenzene or 3-astatotamoxifen, both of which have been synthesized.1,2 This is analogous to "fluoro-", "chloro-", and so on. As a general term, astatine compounds can be referred to as astatides (e.g. aryl astatides, analogous to aryl fluorides, chlorides, etc.).1

The aforementioned synthesis of 3-astatotamoxifen is shown below.

3-astatotamoxifen synthesis

As for inorganic nomenclature, astatine can be denoted with the prefix "astatido-"; this follows from the IUPAC Red Book for nomenclature of inorganic compounds.


  1. Milius, R. A., W. H. McLaughlin, R. M. Lambrecht, A. P. Wolf, J. J. Carroll, S. J. Adelstein, and W. D. Bloomer. Appl. Radiat. Isot. 1986, 37 (8), 799-802.

  2. Samson, G., and A. H. W. Aten. Radiochimica Acta 1970, 13 (4), 220-221.

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There's a page for it on Wikipedia. Have a go at reading it.

https://en.wikipedia.org/wiki/Hydrogen_astatide

There's something interesting here. With Astatine being so electropositive, dissociation of $\ce{HAt}$ could form $\ce{H-}$ and $\ce{At+}$. If you tried to add this to propene, you would most probably get 1-astatopropane rather than 2-astatopropane.

Don't push your luck too far. Before you can call your fellow chemistry buddy and say "Hey look here! This is 1-astatopropane!" It's gone. That's because Astatine is highly radioactive:

$$\ce{^{210}_{85}At -> ^{206}_{83}Bi + ^{4}_{2}He}$$

With a half life of 8.1 hours, your beloved 1-astatopropane is going to decay away, leaving only a trail of alpha particles, and a few gamma photons. sob

Actually, for that matter even $\ce{HAt}$ isn't going to be there for long.

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    $\begingroup$ The logical follow-up question: what happens to the 1-astatopropane molecule once its astatine has become bismuth? Could you conceivably use this to wedge bismuth atoms into molecules where they wouldn't normally go? $\endgroup$ – zwol May 28 '17 at 22:05
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    $\begingroup$ @zwol A nuclear decay releases so much energy compared to a chemical bond that chemistry can be ignored when considering nuclear decay. In practice you'll probably end up with ionized bismuth, hydrogen and helium after decay. $\endgroup$ – ntoskrnl May 29 '17 at 0:45

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