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Topic: Naming alkanes  (Read 13081 times)

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Offline gsel

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Naming alkanes
« on: January 21, 2014, 07:16:44 AM »
What will be the IUPAC name for this molecule (CH3)2CHC(CH3)2CH2CH2CH3?

Offline discodermolide

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Re: Naming alkanes
« Reply #1 on: January 21, 2014, 07:20:02 AM »
What is your suggestion for a name?
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Offline gsel

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Re: Naming alkanes
« Reply #2 on: January 21, 2014, 07:30:11 AM »
It would have to be something like a nonane, but the parentheses confuses me. I dont see if they should be interpered as branches, or what?

Offline discodermolide

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Re: Naming alkanes
« Reply #3 on: January 21, 2014, 07:42:17 AM »
The brackets are a way of saying that there are 2 methyl groups attached to the CH group. (CH3)2CH-
To find the parent you need to find the longest carbon chain.
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Offline Borek

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Re: Naming alkanes
« Reply #4 on: January 21, 2014, 07:46:04 AM »
Depends.

CH3CH2CH2CH3

would mean

CCCC

and can be also written as

CH3(CH2)2CH3.

But

(CH3)2CHCH2CH3

means there are two CH3- groups attached to the first carbon (see it has only one hydrogen attached and is listed as CH?) so it is

C(C)(C)CC

And yes, when the parentheses show inside of the molecule, they can mean branches - just count hydrogens and valencies to be sure. -(CH2)n- always means a chain, but (CH3) must be a branch.

(Edit: disco was faster, but I guess my SMILES are still worth posting ;) ))
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Offline gsel

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Re: Naming alkanes
« Reply #5 on: January 21, 2014, 08:06:24 AM »
Aha! Then in my case I would go for 2,3,3-trimethylhexane. How about that?

Offline discodermolide

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Re: Naming alkanes
« Reply #6 on: January 21, 2014, 08:08:57 AM »
Sorry, nope. What is the longest carbon chain?
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Offline gsel

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Re: Naming alkanes
« Reply #7 on: January 21, 2014, 08:14:38 AM »
I thought of it as two methyl groups attached to 1st and 2nd carbon. If I start counting from the first methylgroup I will end up with six carbons in a row with three methyl groups branched of. If I would not start counting from the methyl group I get 1,1,2,2-tetramethylpentane, but i dont see why i cannot count with the methyl to get the longest chain possible?

Offline discodermolide

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Re: Naming alkanes
« Reply #8 on: January 21, 2014, 08:22:02 AM »
2,3,3-trimethylheptane

CC(C)C(C)(C)CCCC
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Offline SadBloke

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Re: Naming alkanes
« Reply #9 on: January 22, 2014, 04:28:32 AM »
I'm a little confused...I only count 9 carbons in the original post but I count 10 in Disco's answer...

I get 2,3,3-trimethylhexane, as well.

 ???

Offline discodermolide

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Re: Naming alkanes
« Reply #10 on: January 22, 2014, 05:04:25 AM »
I must apologise, I mis-read the structure:
CC(C)C(C)(CCC)C

2,3,3-trimethylhexane
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