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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: ninreznor on March 04, 2013, 08:48:38 AM

Title: help with systematic naming
Post by: ninreznor on March 04, 2013, 08:48:38 AM
I have a coumpound in my worksheet i'm trying to figure out but i can't seem to get my head around it.
this is how it appears in the book.

                O
                "
CH3CH2CH2C-H
           |
           CH2CH2CH3


hope you can understand that.
so what i thought is that because the carbonyl group doesn't appear at the end of the chain but has an hydrogen attached to the carbon atom then it is an aldehyde.
longest chain of carbons is 6 so hexan but if the carbonyl isn't on the cahin then it must be a hexane ring
so what i have is cyclohexancarbaldehyde?
is this anywhere near close?
Title: Re: help with systematic naming
Post by: Hunter2 on March 04, 2013, 09:02:17 AM
No it is 2-Ethyl-pentanale. Longest chain has 5 carbon. But on the Second carbon is on hydrogen to much.
Title: Re: help with systematic naming
Post by: billnotgatez on March 04, 2013, 09:43:46 AM
@Hunter2
A GOOGLE search gives the possibilities
2 ethyl pentanoate   
ethyl 2 methylpentanoate   
2-ethyl-3- methylpentane

not
2-Ethyl-pentanale

And none of them appear to have just 1 oxygen
Title: Re: help with systematic naming
Post by: Hunter2 on March 04, 2013, 12:22:58 PM
Here we go: http://www.chemspider.com/Chemical-Structure.81914.html
Title: Re: help with systematic naming
Post by: ninreznor on March 04, 2013, 12:29:52 PM
Sorry i got the formula wrong it's

            O
             "
CH3CH2CC-H
           |
           CH2CH2CH3

The only thing i can't understand is the -CHO group.
at first i thought it was 2-(1-methylethyl) butanal, but i keep coming up with different names and i'm not sure where to start the chain.
Title: Re: help with systematic naming
Post by: Hunter2 on March 04, 2013, 12:37:35 PM
              O
              "
CH3CH2CHC-H
           |
           CH2CH2CH3

That is the longest chain.
Title: Re: help with systematic naming
Post by: billnotgatez on March 04, 2013, 01:25:21 PM
CCCC(CC)C=O

I tried this in SMILES
it does not quite look like the one on
http://www.chemspider.com/Chemical-Structure.81914.html

but it is very similar
Title: Re: help with systematic naming
Post by: Hunter2 on March 04, 2013, 01:43:55 PM
What means similar.

It is the same compound.
Title: Re: help with systematic naming
Post by: billnotgatez on March 04, 2013, 04:16:25 PM
The 5 carbon backbone is not the same shape
the oxygen faces a different direction

but you are right baring the look it appears to be the same
This is my first post in SMILES
Title: Re: help with systematic naming
Post by: Borek on March 04, 2013, 05:35:08 PM
The 5 carbon backbone is not the same shape
the oxygen faces a different direction

You have to remember single bonds are not stiff, they rotate.