Organikum
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Stupid nomenclatura question
Why is beta-hydroxy-methamphetamine the same as alpha-hydroxy-beta-methylaminopropyl benzene aka ephedrine?
Is the hydroxy group now on the alpha or the beta carbon?
How would you name the carbon on which the hydroxy group of ephedrine is attached? Alpha or beta?
confused
/ORG
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S.C. Wack
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http://www.cognitiveliberty.org/shulgin/adsarchive/nomenclat...
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Organikum
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The inventors of chemical nomenclatura should be crucified.
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JohnWW
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What do you think would be the best way of synthesizing it? As well as an antihistamine medicine for nasal congestion, it is also good for making
speed (methamphetamine), a useful performance-enhancing drug. (Never mind about its being illegal - taking it will help you fight against the sham
"war on drugs" .
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Kinetic
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Nomenclature is relative!
I agree that this archaic nomenclature is far from ideal. Fortunately it is seldom used nowadays, and only in names of compounds that have become the
'trivial' name (e.g. alpha-bromopropiophenone) does it still prevail.
The terms alpha and beta are no longer used in the naming of whole organic molecules. They are, however, still used to give the position of a group on
a molecule relative to another group. Hence, to explain the reactivity of the bromide leaving group in 2-bromopropiophenone, you would say it was
because it was alpha to the ketone. Likewise, you would use the term beta-keto acid when talking about decarboxylation reactions.
All nomenclature is relative, even now with the more precise and logical numbering system (e.g. 2-(methylamino)-1-phenylpropan-1-ol for your precious
ephedrine). Hence:
Beta-hydroxy-methamphetamine is the same as alpha-hydroxy-beta-methylaminopropyl benzene because, in the first case, the naming is relative to the
amine function. The hydroxy group is beta to this. In the second case, the nomenclature is relative to the benzylic position of the aromatic ring side
chain. So the hydroxy group is alpha (the same as benzyl chloride is also called alpha-chlorotoluene) and the methlyamino group is beta to this same
position. Plain 2-phenylethylamine is also called beta-phenethylamine, as the amine function is beta to the benzylic carbon. | Quote: |
How would you name the carbon on which the hydroxy group of ephedrine is attached? Alpha or beta?
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You wouldn't, normally. But relative to the amine it is beta, just as the methylamino group is beta
the the hydroxy group. Get it?
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Organikum
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Thanks to all.
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What do you think would be the best way of synthesizing it?
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By biosynthesis of l-PAC from benzaldehyde as precursor and with bakers yeast, followed by reductive
alkylation. There is a thread about this here on this board - keyword "hydroxyphenylacetone".
https://sciencemadness.org/talk/viewthread.php?tid=1936
Thats also the industrial method of choice.
Ephedrine is not precious to me. Norephedrine is though.
/ORG
[Edited on 20-5-2005 by Organikum]
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sparkgap
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I was going to post a reply after seeing ORG's question, but apparently Mr. Wack and Kinetic beat me to it. Tsk. 
I'll just offer my two cents worth: I don't think the nomenclature is that much of a problem. That is, as long as the persons conversing
agree on which is "alpha" and which is "beta". The IUPAC system ain't perfect, but it's a manmade system, after all. I
always joked that the way it was set down, one could conjure at least four substantially different, yet exactingly correct systematic names. But I
digress. 
As long as we're talking nomenclature, does anyone know of an e-book version of the IUPAC Blue Book? It's kind of like the final authority
on how to correctly name a substance (at least for organic compounds), and it's quite a sizeable tome. All I've found so far on the web is a
section of it at the ACD Labs site (somewhere there).
sparky (^_^)
"What's UTFSE? I keep hearing about it, but I can't be arsed to search for the answer..."
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