Course reader page 103- cis

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Eman_Burney_1D
Posts: 15
Joined: Wed Sep 21, 2016 2:57 pm

Course reader page 103- cis

Postby Eman_Burney_1D » Sun Mar 12, 2017 9:46 pm

On page 103 of the course reader, the example on top of the page is named cis-2-pentene (example below, ignore the periods):

H_3C..CH_2CH_3
.. \ ...../
.. C=C
.. / .... \
..H .... H

My question is, how is this a cis example, if H_3C and CH_2CH_3 are not the same? Would this be labeled as cis just from the fact that the two hydrogens are on the same side?

Isabella_Pena_3D
Posts: 8
Joined: Sat Jul 09, 2016 3:00 am

Re: Course reader page 103- cis

Postby Isabella_Pena_3D » Sun Mar 12, 2017 9:58 pm

I believe the cis refers to the position saying that the substituents are oriented in the same directions. H_3C and CH_2CH_3 are the substituents. I'm not completely sure, but that's what I thought when I saw it.

Spencer Peterman 3E
Posts: 18
Joined: Fri Jul 22, 2016 3:00 am
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Re: Course reader page 103- cis

Postby Spencer Peterman 3E » Sun Mar 12, 2017 10:01 pm

It actually doesn't need to be the same group on both sides, you're just looking at which group has the highest priority on each side. Both CH3 and CH2CH3 have a higher priority than H because C has a higher atomic number than H, so those are the groups you use to determine if it's cis or trans.


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