Chemical Forums

Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: aspiringphysician on June 19, 2012, 08:27:45 PM

Title: E2 Mechanism Question
Post by: aspiringphysician on June 19, 2012, 08:27:45 PM

I am having trouble figuring out the mechanism for this question:

"The first step in the reaction (pictured below) is the formation of the conjugate base of the starting material. This intermediate will proceed through an E₂-type mechanism where CO₂ is lost in place of a proton. Provide a step-by-step electron-pushing mechanism that accounts for the stereochemistry.  Use perspective representations throughout.  Clearly show and name (E/Z) the stereochemistry of the product."

Are they talking about the conjugate base of K₂CO₃? And I don't understand how CO₂ is lost...does the base take it? Then how does the carboxylic acid proton stay attached to the substrate?  ???

Title: Re: E2 Mechanism Question
Post by: fledarmus on June 19, 2012, 08:31:53 PM

No, the conjugate base is what you get when the acid loses a proton.

Title: Re: E2 Mechanism Question
Post by: aspiringphysician on June 19, 2012, 11:22:15 PM

Ah, okay...thanks, I figured it out now!...and, by the way, the alkene on the right should have been cis, not trans  :P