July 02, 2022, 12:51:35 PM
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Topic: IUPAC naming rules for aromatic rings - special situation  (Read 261 times)

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Offline lord farquaad

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IUPAC naming rules for aromatic rings - special situation
« on: January 31, 2022, 05:33:38 PM »
I named this molecule (picture attached) 4-chloro-5-methylcyclopentan-2-ol. When checking my answers, the given answer was:
4-chloro-5-cyclopentylhexan-2-ol

How would someone know that the cyclopentane is not directly attached to the carbon chain on the fifth carbon?
How can naming show that the fifth carbon is attached to another carbon that is part of the cyclopentane?

Could it be named: 4-chloro-6-cyclopentyl-5-methylhexan-2-ol? Or does that not work because the longest parent chain is not named properly?

Offline Orcio_87

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Re: IUPAC naming rules for aromatic rings - special situation
« Reply #1 on: February 01, 2022, 10:12:26 AM »
Quote
Could it be named: 4-chloro-6-cyclopentyl-5-methylhexan-2-ol?
No, because:

1. cyclopentyl is a substituent at 5, not 6 carbon atom.
2. there is no -CH3 substituent at this hexane derivative.

Offline mjc123

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Re: IUPAC naming rules for aromatic rings - special situation
« Reply #2 on: February 01, 2022, 05:10:52 PM »
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How would someone know that the cyclopentane is not directly attached to the carbon chain on the fifth carbon?
How can naming show that the fifth carbon is attached to another carbon that is part of the cyclopentane?
Because that is what "cyclopentyl" means. The cyclopentyl group is a cyclic C5H9 unit attached by a single bond (not part of the ring) to another atom. "5-cyclopentyl" does not mean that C5 of the chain is included in the cyclopentane ring. The compound you appear to be thinking of would be 4-chloro-4-(1-methylcyclopentyl)butan-2-ol.

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