Organic chemistry

[Gholam2020]

Hello SDN,
I have question regarding Cis and trans! I came cross question on destroyer that ask about IR spectroscopy and the answer was trans molecules! Can some one explain difference between cis and trans and their stabilities?
Thanks in advance,


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[DAT Destroyer]

Hello SDN,
I have question regarding Cis and trans! I came cross question on destroyer that ask about IR spectroscopy and the answer was trans molecules! Can some one explain difference between cis and trans and their stabilities?
Thanks in advance,


Sent from my iPhone using SDN mobile

If you have a double bond or ring, cis-trans isomerism is possible. Draw two carbons and place a double bond between them. Now on one carbon place a Cl......and on the other carbon place a Cl. If they are on the same side, you have cis. If they are opposite each other, you have trans. Consult any organic text to see a few more examples. As a general rule, the trans isomer is more stable since there is less Van Der Waals repulsions between the electron clouds and the groups. In IR spectroscopy. we stretch a bond using IR radiation. Only molecules with dipoles will give a signal for the functional group under consideration. Consider trans-1, 2-dichloroethene. This molecule has NO dipole since the Cls, cancel each other out. Thus, we say it is IR inactive. The cis isomer has a dipole, since the Cls are pointing in the same direction. This molecule is IR active, and we see a strong signal at about 1650cm-1.

I hope this helps.

Dr. Jim Romano

 

[FeralisExtremum]

Hello SDN,
I have question regarding Cis and trans! I came cross question on destroyer that ask about IR spectroscopy and the answer was trans molecules! Can some one explain difference between cis and trans and their stabilities?
Thanks in advance,


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Have you taken an organic chemistry course yet?

 

[Gholam2020]

Thanks doctor Romano for great explanation!


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[Gholam2020]

Yes I have taking organic Chem 1 and organic Chem 2


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