c

|

c - c - c

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c

 

Just started organic chemistry in high school. In the above diagram there are three hydrogens hanging off the four outer carbons. Is the answer 2,2-dimethylpropane or 2-dimethylpropane?

 

edit: hold on those 2 carbons- the one at the top and the one below is supposed to be attached to the middle 2nd carbon of propane but I can't draw it properly for some reason.

2,2-dimethylpropane (aka neopentane, sometimes it's just called dimethylpropane). But if you're naming it systemically, you have to include the 2,2- part so it's unambiguous about exactly where those methyl groups are situated.

Edited May 11, 201015 yr by Greippi

Ok, thanks for the help!

Actually, according to IUPAC the longest carbon chain is the parent. Thus the name would be 2-methylbutane

Actually, according to IUPAC the longest carbon chain is the parent. Thus the name would be 2-methylbutane

 

Read the original post carefully. The diagram isn't what it seems...

2,2-dimethylpropane (aka neopentane, sometimes it's just called dimethylpropane). But if you're naming it systemically, you have to include the 2,2- part so it's unambiguous about exactly where those methyl groups are situated.

 

actually the 2,2 part isn't necessary because if the methyl groups were on the 1- or the 3- positions, the parent chain would be longer and there'd be an entirely different name.

 

from wikipedia:

 

IUPAC nomenclature retains the trivial name neopentane. The systematic name is 2,2-dimethylpropane, but the substituent numbers are unnecessary because it is the only possible "dimethylpropane".

The longest carbon chain has 4 carbon atoms. By IUPAC naming conventions the position of a functional group or in this case the methyl group should have the smallest possible integer number.

So the name should be 2-methyl Butane.

 

oops i didnt know the question had already been answered.