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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: THC on January 13, 2009, 01:39:19 PM

Title: Difference in isomers in NMR?
Post by: THC on January 13, 2009, 01:39:19 PM

Hi

Is it possible to distinguish between two stereoisomers (diastereomere and enantiomere) with H/C-NMR?

And is it possible to distinguish between a staggered conformation and an eclipsed conformation (like here:http://en.wikipedia.org/wiki/Linear_alkane_conformation if the substituents were other thing than H)?

Title: Re: Difference in isomers in NMR?
Post by: playstyles on January 13, 2009, 03:06:38 PM

I believe that enantiomers you cannot, diastereoisomers you can.
Cis and trans variations are generally included in diastereoisomers, and those can be
perceived as different in NMR.
Enantiomers, or mirror images have similar proton or carbon NMR as their connectivity is identical.

Title: Re: Difference in isomers in NMR?
Post by: dfodor on January 13, 2009, 04:34:09 PM

It depends on the molecule. For example if it is a substituent on a benzene ring you have the chance to make a difference (shading effect of benzene ring).

Title: Re: Difference in isomers in NMR?
Post by: cumshyster on January 28, 2009, 12:08:06 PM

Power...it all is a question of power...do you have enuf ? BWAAAAHAHAHA

Title: Re: Difference in isomers in NMR?
Post by: aldoxime_amine on January 28, 2009, 02:34:40 PM

Quote from: dfodor on January 13, 2009, 04:34:09 PM

It depends on the molecule. For example if it is a substituent on a benzene ring you have the chance to make a difference (shading effect of benzene ring).

What does "shading effect of benzene ring" mean?