Cis/Trans

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Mya Majewski 1L
Posts: 89
Joined: Fri Sep 25, 2015 3:00 am

Cis/Trans

Postby Mya Majewski 1L » Mon Feb 29, 2016 8:34 pm

Can someone explain the main differences between a cis and trans isomer? How could you tell looking at a molecule whether it is one or the other?

Albert Chong_1L
Posts: 77
Joined: Fri Sep 25, 2015 3:00 am

Re: Cis/Trans

Postby Albert Chong_1L » Mon Feb 29, 2016 8:45 pm

First of all, cis and trans isomers occur only when there are double bonds in the molecule.

To determine cis or trans, look individually at each carbon and what is connected to it.
Decide which of the two species connected to each carbon is greater in atomic number, and if they are the same, keep moving down the chain until you can say either one species or the other has greater atomic number.
Do this for both carbons in the double bond.

If both species with greater atomic number are on the same side of the carbons, it is cis.
If the species with greater atomic number are split on both sides, it is trans.

Amanda Reshke 1D
Posts: 17
Joined: Fri Sep 25, 2015 3:00 am

Re: Cis/Trans

Postby Amanda Reshke 1D » Mon Feb 29, 2016 9:40 pm

Can cis and trans isomers also occur when there are triple bonds?

Albert Chong_1L
Posts: 77
Joined: Fri Sep 25, 2015 3:00 am

Re: Cis/Trans

Postby Albert Chong_1L » Tue Mar 01, 2016 8:10 pm

Nope. Because for triple bonds, there is only one structure possible. A linear one.


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