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Topic: IUPAC nomenclature for large arenes.  (Read 4835 times)

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Offline mreff555

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IUPAC nomenclature for large arenes.
« on: February 26, 2009, 01:32:28 PM »
I can't figure out the proper numbering method for large arenes. I have to synthesize trans-9-(2-phenylethenyl)-anthracene tomorrow, and I just want to understand the compound a little better. I'm clear on the rest of the molecule but I can't understand the 9. I know that it is speaking of the substituent location of the Phenylethenyl group, on the anthracene group. I just don't understand why the number is so High. I could guess that joined rings would be named similar to bi-cyclic rings but if that was the case I would expect a locant of 7. can someone please explain.



Offline James Newby

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Re: IUPAC nomenclature for large arenes.
« Reply #1 on: February 26, 2009, 02:17:33 PM »
http://en.wikipedia.org/wiki/Anthracene

The numbering is just how IUPAC chose to do it, the central ring is the one that does all the interesting chemistry, so i assume its like that to separate it from the 'benzene like' carbons.  All research journals you read will number it like this as well
4th year undergraduate at the University of Sheffield

Offline mreff555

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Re: IUPAC nomenclature for large arenes.
« Reply #2 on: March 01, 2009, 12:19:59 PM »
What about those four unnumbered bridge carbons?
http://en.wikipedia.org/wiki/Anthracene

The numbering is just how IUPAC chose to do it, the central ring is the one that does all the interesting chemistry, so i assume its like that to separate it from the 'benzene like' carbons.  All research journals you read will number it like this as well

Offline James Newby

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Re: IUPAC nomenclature for large arenes.
« Reply #3 on: March 01, 2009, 03:03:50 PM »
Im not sure to be honest! You cannot add substituents to them as they are saturated already, maybe that plays a part.  How was your synthesis?  Ive applied for a PhD involving using anthracene so im interested in the area
4th year undergraduate at the University of Sheffield

Offline sjb

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Re: IUPAC nomenclature for large arenes.
« Reply #4 on: March 01, 2009, 04:06:47 PM »
What about those four unnumbered bridge carbons?

The bridge atoms will be numbered using things like 4a, 4b etc. See http://www.chemsynthesis.com/base/chemical-structure-22928.html for an example.

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