Chemical Forums

Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: HorseFurHire on January 10, 2011, 02:18:23 PM

Title: Nomenclature issues?
Post by: HorseFurHire on January 10, 2011, 02:18:23 PM

So I am having trouble trying to find the name of a certain molecule:

(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Fimg443.imageshack.us%2Fimg443%2F5853%2Fchemmodelmodified.png&hash=064dce51100916d7e306e19e9722306a9195cab7) (http://img443.imageshack.us/i/chemmodelmodified.png/)

I used the red circle to illustrate the parent group and the green circle to show the side group in question. I have no idea how that would be pronounced. Would that be under the isobutyl category?

Title: Re: Nomenclature issues?
Post by: sjb on January 10, 2011, 04:07:46 PM

Are you sure that the red group is the parent here?

Title: Re: Nomenclature issues?
Post by: HorseFurHire on January 10, 2011, 04:58:18 PM

I'm pretty sure it is since it looks to be the longest chain that involves the double bond within the structure.

Title: Re: Nomenclature issues?
Post by: sjb on January 11, 2011, 02:26:01 AM

Quote from: HorseFurHire on January 10, 2011, 04:58:18 PM

I'm pretty sure it is since it looks to be the longest chain that involves the double bond within the structure.

Fair enough, I was thinking more that the longest chain didn't need the double bond and I'd name that branch as a substituent. In that case, no the green group is not an iso-butyl, there are 6 carbons, for a start

Title: Re: Nomenclature issues?
Post by: discodermolide on January 11, 2011, 04:16:33 AM

Quote from: HorseFurHire on January 10, 2011, 02:18:23 PM

So I am having trouble trying to find the name of a certain molecule:

(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Fimg443.imageshack.us%2Fimg443%2F5853%2Fchemmodelmodified.png&hash=064dce51100916d7e306e19e9722306a9195cab7) (http://img443.imageshack.us/i/chemmodelmodified.png/)

I used the red circle to illustrate the parent group and the green circle to show the side group in question. I have no idea how that would be pronounced. Would that be under the isobutyl category?

Look for the longest carbon chain first, that is NOT the red one.

It's name is (Z)-4,8-diethyl-3-methyl-6-(prop-1-en-1-yl)-5-propyldecane (obtained from chem draw)

Title: Re: Nomenclature issues?
Post by: orgstudy on January 11, 2011, 05:21:48 AM

If you consider the red chain as the longest chain,
name is: (Z)-4-(2ethylbutly)-5-propyl-6ethyl-7-methylnonene

But the structure acc. to discodermolide name is this ... (pic)

___________________________________________________________________________________________________________________________

But i thought that the double bond should be included in this molicule!!

Isn't that so???

Title: Re: Nomenclature issues?
Post by: Jesse2024 on January 11, 2011, 07:38:33 AM

I am pretty sure when naming compounds you have to pick the longest carbon chain that includes the highest number of double and/or triple bonds.

In this case it would be as OP has drawn, the longest carbon chain inclusive of the double bond is in red.

Title: Re: Nomenclature issues?
Post by: orgstudy on January 11, 2011, 10:12:15 AM

But still I remember examples in which the longest bond donot contain all the double or tripe bonds ... one was in this website only

This might be one of the wrong rule taught us in schools!!!

please someone check will the double bond should be included or not!!!!

Title: Re: Nomenclature issues?
Post by: discodermolide on January 11, 2011, 10:13:55 AM

Quote from: Jesse2024 on January 11, 2011, 07:38:33 AM

I am pretty sure when naming compounds you have to pick the longest carbon chain that includes the highest number of double and/or triple bonds.

In this case it would be as OP has drawn, the longest carbon chain inclusive of the double bond is in red.

The name I posted is correct, even according to CAS online.