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Topic: Cycloalkane Naming Help  (Read 4853 times)

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Offline _Weirdo_0.o

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Cycloalkane Naming Help
« on: October 14, 2012, 07:15:38 PM »


There's a picture of the problem from one of my quizzes.  I have the solution but don't understand it.
Can anyone tell me why the longest chain is that cyclohexadexane?  Are you just supposed to know that it's a cyclo with huge substituents? The answer is:

3,3-dibromo-1-sec-butyl-6-tert-butyl-2-heptyl-7-cycloheptyl-13-isobutyl-14-isopropyl-5,12-dimethyl-10-neopentyl-8-pentadecyl-4-propylcyclohexadecane

Offline EpicWinston

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Re: Cycloalkane Naming Help
« Reply #1 on: October 14, 2012, 07:42:26 PM »
Because the longest carbon chain is the cyclohexadecane (16 carbons) its in the middle

Offline EpicWinston

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Re: Cycloalkane Naming Help
« Reply #2 on: October 14, 2012, 07:48:30 PM »
Here is a picture for clarity

Offline _Weirdo_0.o

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Re: Cycloalkane Naming Help
« Reply #3 on: October 14, 2012, 08:08:09 PM »
During the test, I didn't see the cyclo so I started at the end of that pentadecane  ::)
But, the rule is: look for the longest CONTINUOUS chain?  My prof never specified.. that, or I wasn't paying attention Dx

Offline EpicWinston

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Re: Cycloalkane Naming Help
« Reply #4 on: October 14, 2012, 08:20:04 PM »
yea the rule is look for the longest continuous chain.

Offline _Weirdo_0.o

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Re: Cycloalkane Naming Help
« Reply #5 on: October 14, 2012, 08:25:04 PM »
Thanks again!  :)
Also, can you please explain neo-pentyl and iso-pentyl's names?  Like, I understand that tert-butyl uses "tert" because the middle Carbon is attached to 3 other carbons.  But, why neo and iso?

Offline EpicWinston

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Re: Cycloalkane Naming Help
« Reply #6 on: October 14, 2012, 10:00:01 PM »
It depends on how many carbons are bonded to the alkyl group: alkyl groups with the prefix iso has a secondary carbon, alkyl groups with the prefix tert has a tertiary carbon, and alkyl groups with the prefix neo has a quaternary carbon.

Offline EpicWinston

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Re: Cycloalkane Naming Help
« Reply #7 on: October 14, 2012, 10:05:06 PM »
You are probably going to ask how to identify primary, secondary, tertiary and, quaternary.
primary - bonded to one carbon atom
secondary - boned with two carbon atoms
tertiary - bonded with three carbon atoms
quaternary - bonded with four carbon atoms

Offline _Weirdo_0.o

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Re: Cycloalkane Naming Help
« Reply #8 on: October 15, 2012, 12:50:05 AM »
Thanks so much  :)
I'll probs be back with more questions haha

Offline EpicWinston

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Re: Cycloalkane Naming Help
« Reply #9 on: October 15, 2012, 04:45:48 PM »
here was the picture I forgot to post  :P

Offline _Weirdo_0.o

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Re: Cycloalkane Naming Help
« Reply #10 on: October 15, 2012, 09:19:28 PM »
Thanks  :)

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