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Topic: Chemical Naming Help  (Read 1719 times)

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Offline jcobb

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Chemical Naming Help
« on: January 21, 2017, 08:34:33 PM »
Hey. I was just reading an article on celecoxib and it gives the IUPAC name is:

4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamide

It's been a couple years since I took organic chemistry, and I'm wondering what the "1H" and the "1-yl" parts of this name mean.


Offline pgk

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Re: Chemical Naming Help
« Reply #1 on: January 22, 2017, 09:08:29 AM »
The prefix [1H] denotes which atom of the ring, is “saturated”.
Note that pyrazole is a 5 member aromatic ring but contains only two double bonds and therefore, one of it’s atoms, is always “saturated” and does not participate in a double bond.
The termination –yl denotes the substituent ring, e.g.
Thiophene → Thiophenyl-
Pyridinne → Pyridyl-
Piperidine → Piperidinyl-
But, Benzene → Phenyl-
The termination 1-yl denotes which atom of the substituent ring binds with the substituted one.
IUPAC nomenclature might sometimes differ from Chemical Abstracts or emprical and common names that are met in the litterure or even, in official texts. Besides, IUPAC nomenclature changes from time to time. Example:
IUPAC today: butane-1-ol
IUPAC former (before 60s): butanol-1
CA index: butane, 1-ol, butane 1-ol
Common name: normal butanol, n-butanol
Empirical name: butanol
« Last Edit: January 22, 2017, 10:48:37 AM by pgk »

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