KCN, Acetone react Benzyl Chloride

[Ibraiz]

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Why doesn't KCN in an acetone solvent react with Benzyl Chloride. NaCN is a strong nucleophile (although weak base) and perfect for Sn2 reaction. I was thinking KCN would be same. Acetone being the solvent should make it more prone to go Sn2. Why is there no reaction?



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[Veloce]

Aryl Halide's are not reactive towards SN2.

http://www.cliffsnotes.com/study_gu...des.topicArticleId-23297,articleId-23268.html

I am doing Dr. Romano's Organic chemistry odyssey, and it's really good, it covers things like this well.

 

[Ibraiz]

I didn't even think about that.

Just to confirm: Aryl halide, vinylic halide, cyclic halide are all unreactive in Sn1 and Sn2, correct?

 

[Veloce]

I'm no Organic chem buff, but:

Cyclic halides will undergo sn2

Vinylic and aryl halides will not undergo sn1 or sn2, I read it is becasue the Hydrogen has partial double bond character making it difficult to remove.

Also remember both are secondary carbons making them even less favorable for sn2.

 

[rpatel8]

If the leaving group is on a Sp2 hybridized carbon, there will be no reaction. No SN1, SN2, E1, or E2.