Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: joshphillips1977 on December 08, 2013, 07:04:37 PM

C

CCCCC

C
I came up with 3propylpentane, would that be correct?

Find the longest carbon chain.

Sorry about that was suppose to have been 5 in the longest chain.

OK 5 carbon chain. What about the substituents?

C

C

CCCCCC
 
C C

C

C
I came up with 2 propyl 2butyl 4ethylhexane, but am unsure if this is correct?

It's on the third carbon (so 3) and there are 3 substituents (so Prop)...
3prop

No, there are two substituents on that carbon.

Ah so then it would be (2ethyl 2ethyl)

No, where do you get ethyl from, there are only two 1 carbon substituents on that middle carbon. If that makes sense.

kind of so what your saying is I count the one to the left and the one to the right but not the carbon that is in the longest chain. So essentially it would be 2methyl 2methyl...

is 3,3dimethylpentane

alright now I am confused

Why?

joshphillips1977: I hope you don't mind me merging your two threads on nomenclature. Once you figure out one, you may have what you need to solve the other. Sorry if the order is a little screwy for you and everyone else though.

The Dim

you have a CCCCC chain with a C and a C on the third carbon, a C is a methyl group, that is 3,3dimethylpentane

Okay sorry I feel stupid, how do you get the 3,3 and the Di?

the numbering, count from one end of the chain, the two methyls (Di) are on the third carbon,
3,3dimethylpentane, di meaning two!

Okay slap me if I still don't have it. So the carbon on the left is the one substituent and the one on the right is the second not counting the C in the longest chain that puts each one in the Meth group... for example had there been one C on the left and two C to the right it would have been 3methyl 3ethylpentane

I say again you have a 5 carbon chain.
CCCCC on the middle carbon there are two substituents two methyl groups.
the longest chain is 5 C atoms i.e. a pentane, on the middle carbon number 3 are two methyl substituents, i,e, dimethyl.
so you have 3,3dimethylpentane.
No magic, that's it.

why the two threes?
C

C

CCCCCC
 
C C

C

C
Which makes this one 2propyl 2ethyl 4methylHexane Right? could I say 2,2,4 propylethylmethylHexane?

No again find the longest carbon chain

the longest chain would be six

No the longest chain is 8.
Back to the other one, the two "3"s, this is because the two substituents are on the same carbon, carbon number 3, hence 3,3dimethyl.

see picture.

Okay so them both being on the 3rd carbon makes sense, two substituents both on carbon 3 and both methyl

Thats correct.
Now what about the other one, look at the picture I posted.

see picture.
Oh Snap I get what your saying now... so i am gonna try to answer the second one again and repost...

see picture.
4,6 dimethyl 4ethylOctane??

Not quite it is 5ethyl3,5dimethyloctane.
the substituents go in alphabetical order.
Then the sum of the numbers must be the lowest, that is in your name the substituents are not in alphabetical order, and the numbers add up to 14.
In my name they are in alphabetical order and the sum is 13.

Awesome I think I got it, I was suppose to have numbered my chain from right to left this time rather than left to right. Thanks!

My pleasure.

and if I wanted to express methanol similarly I would do it like: