Course Reader: 3,6-Dimethyl-3-Octene

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004643111
Posts: 14
Joined: Fri Sep 25, 2015 3:00 am

Course Reader: 3,6-Dimethyl-3-Octene

Postby 004643111 » Wed Mar 09, 2016 10:13 am

In the course reader on page 105, Dr. Lavelle said that the 3,6-Dimethyl-3-Octene is E. Essentially, you can see that since the substituents are on opposite sides right? Figuring this out by comparing higher priority groups however is confusing me. He said you compare the Hydrogen and Carbon and the carbon would be the priority, however, on the left side, both branches attached to the double bond are carbons. Are you not supposed to look at the next immediate atoms to see which is the priority?

Umair Khan 2G
Posts: 32
Joined: Fri Sep 25, 2015 3:00 am

Re: Course Reader: 3,6-Dimethyl-3-Octene

Postby Umair Khan 2G » Wed Mar 09, 2016 10:29 am

You are essentially right when talking about priority for naming Z and E. Lets start with the right side first
The carbon on the right is connected to a hydrogen (not shown) and the rest of the carbon chain. Since the carbon is angled down, the hydrogen must be pointed up. Also, since carbon has a bigger atomic number it gets priority.
Now for the carbon on the left. Look we see that the carbon is connected to a Methyl group, and the rest of the carbon chain. Both these molecules have the carbon, as we look at the next immediate molecule. For the methyl group, this is a hydrogen, and for the carbon chain it is another carbon molecule. Again, since the Carbon a bigger atomic number, it gets priority. Looking at the left hand side, we see that the chain that is given priority is pointing up.
Now comparing both double-bonded carbons, we can note that the side on the left has the group with priority pointing up, and the side on the right has the group with priority pointing down. As such, we can call the structure Trans or (E).


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