Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Hikaru on July 29, 2008, 12:03:29 PM
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SNi is intramolecular substitution reaction.
How is it different from SNi'?
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' usually refers to allylic substitution. in general:
H2C=CH-CH2-LG + Nuc: --> Nuc-CH2-CH=CH2
where the nucleophile attacks the carbon of the double bond, the electrons move to form a new double bond on the adjacent carbon, and the leaving group leaves.
This might be what it refers to here.
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I think this has more to do with nucleophillic substitution that occurs within a molecule with itself.
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I think this has more to do with nucleophillic substitution that occurs within a molecule with itself.
But if SNi is already intramolecular, then what designation would the ' have?
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Here's the SNi wikipedia page.
http://en.wikipedia.org/wiki/SNi
Seems more like substitution resulting from tight ion pair, thus proceeding with retention. So maybe this general mechanism, but with allylic substitution?
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Thanks a lot.
I think it is like azmanam said - that it is allylic substitution.
Can it be both allylic substitution and intermolecular?
Actually this question comes from a problem:
Which one reacts with SOCl2the fastest?
Ph-CH2OH
CH2=CHCH2OH
CH3CH=CHOH
CH3CH2CH2OH
I am told they occur through SNi' mechanisms.
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careful with your prefixes. SN2' reactions are the intermolecular ones. The whole point here is that we're dealing with SNi' reactions, which are intramolecular.
Let's assume that SNi' refers to intramolecular allylic substitution. Which compound appears capable of allylic substitution under this mechanism? What is the mechanism for this SNi' reaction?
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Better late than never, right?
Here's a page talking specifically about SNi' that actually refers to one of the choices in the multiple choice question:
http://www.cem.msu.edu/~reusch/VirtTxtJml/special2.htm#top6