Determining cis, z, trans, or e  [ENDORSED]

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Nathan Sanchez 1F
Posts: 12
Joined: Sat Jul 09, 2016 3:00 am

Determining cis, z, trans, or e

Postby Nathan Sanchez 1F » Sun Mar 19, 2017 2:27 pm

Is cis always Z and is trans always E? If not, why?

Jenny2G
Posts: 31
Joined: Wed Sep 21, 2016 2:56 pm

Re: Determining cis, z, trans, or e

Postby Jenny2G » Sun Mar 19, 2017 2:30 pm

Cis means same side which is the same as Z while trans means the opposite side which means E. So cis is always Z and trans is always E.

Chem_Mod
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Re: Determining cis, z, trans, or e

Postby Chem_Mod » Sun Mar 19, 2017 4:51 pm

Jenny2G wrote:Cis means same side which is the same as Z while trans means the opposite side which means E. So cis is always Z and trans is always E.


Incorrect.

Vincent Tse 2B
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Re: Determining cis, z, trans, or e  [ENDORSED]

Postby Vincent Tse 2B » Mon Mar 20, 2017 12:54 am

The E/Z naming system is used particularly for naming alkenes, determined by identifying the priority group bonded to the carbons: if the priority groups are on the same side, it is Z; if opposite, it is E.

Cis and trans refer to conformations and the direction of substituents in either axial or equatorial bonds. If the substituents point in the same direction (e.g. axial down and equatorial down) then it is cis. Note, that the type of bond does not matter, only the direction. If the substituents point in opposition (e.g. axial up and axial down), then it is trans.


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