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Topic: Wittig reactions  (Read 2972 times)

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Offline webguy54

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Wittig reactions
« on: March 20, 2008, 06:48:51 PM »
Are Wittig reactions and the Horner-Emmons-Wadsworth modification of the Wittig reactions classified as substition reactions?

The sections containing both reactions directly follow a section entitled "Addition of Carbon Nucleophiles."  I believe they're substition reactions, but I would like to make sure since the chapter text doesn't state that it's speaking about anything else but addition reactions of aldehydes and ketones.

Thank you for your help.

Offline azmanam

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Re: Wittig reactions
« Reply #1 on: March 20, 2008, 09:46:28 PM »
I would not consider it a 'substitution reaction'.  The first step is carbonyl addition, but I would classify the net reaction as an 'olefination reaction' - one that introduces an alkene.

The preparation of the ylide begins with a substitution reaction, but I would not consider the Wittig or HWE as substitution reactions.

see here:
http://www.mnstate.edu/jasperse/Chem365/Wittig.doc.pdf
http://en.wikipedia.org/wiki/Wittig_reaction
http://www.chem.ucalgary.ca/courses/351/Carey5th/Ch17/ch17-3-2-3.html
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