I realized that I unnecessarily took points in grading the first mechanism. Many students showed deprotonation of oxygen before loss of formaldehyde as a leaving group. While this step looks unfavorable, it is the reverse of the first step of imine formation in which an amine attacks an aldehyde creating a negatively charged oxygen. Since the whole reaction is in equilibrium according to the Principle of Microscopic Reversibility, this step should be retraced in the reverse reaction. A couple students got 2pts back on this question while some got 3. The new mean grade is 61.2, and the median is 63.5. Check blackboard to see if you gained any points.
Posted on: Sun, 05 Oct 2014 04:07:11 +0000
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