Quick NMR question

[virtualmaster999]

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Hey everyone

I'm just getting a bit thrown up on chemical equivalence of protons for Alkenes. Is the easiest way to determine chemical equivalence for Alkenes by using the "z" method, where you swap an atom?

In that case, does that make both cis and trans 1,2-dichloroethene have just one signal?

Thanks in advance!


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[DAT Destroyer]

Hey everyone

I'm just getting a bit thrown up on chemical equivalence of protons for Alkenes. Is the easiest way to determine chemical equivalence for Alkenes by using the "z" method, where you swap an atom?

In that case, does that make both cis and trans 1,2-dichloroethene have just one signal?

Thanks in advance!


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Simply look at the environment they are located. Since there is no rotation about a double bond,,,,,,simply note which atoms are next to you and on the same carbon. For trans-1,2-dichloroethene.....both H's are across from a Chlorine......and bonded to an carbon with a chlorine...........thus 1 signal. The Cis isomer also gives 1 signal by similar analysis.

Hope this helps!
Dr. Jim Romano

 

[virtualmaster999]

Simply look at the environment they are located. Since there is no rotation about a double bond,,,,,,simply note which atoms are next to you and on the same carbon. For trans-1,2-dichloroethene.....both H's are across from a Chlorine......and bonded to an carbon with a chlorine...........thus 1 signal. The Cis isomer also gives 1 signal by similar analysis.

Hope this helps!
Dr. Jim Romano

So does that mean that a compound that is in the cis positions with two exact groups and two hydrogens (similar to dichloroethene) and one that is trans with the same exact groups with two hydrogens (like dichloroethene ) will have identical hydrogens?


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[DAT Destroyer]

So does that mean that a compound that is in the cis positions with two exact groups and two hydrogens (similar to dichloroethene) and one that is trans with the same exact groups with two hydrogens (like dichloroethene ) will have identical hydrogens?


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Yes.....the cis and trans isomers of this simple alkene has 2 chemically equivalent protons,,,,,,,both graphs give singlets,,,,,,,,

Dr. Romano

 

[virtualmaster999]

Thanks!


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