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Problem of the Day #08 – Answer Key Deadline : 3:00 p.m., Monday, 7/28/08 LATE WORK WILL NOT BE ACCEPTED OR GRADED!!! This problem is worth a total of 20 raw points. In lecture, we discussed the Wolff-Kishner reduction, which occurs when an aldehyde or ketone is heated with hydrazine (H 2 NNH 2 ) in the presence of concentrated KOH. The overall transformation observed for the Wolff-Kishner reduction of acetophenone is shown below: Ph CH 3 O H 2 NNH 2 KOH, Ph CH 3 N NH 2 KOH, Ph CH 2 CH 3 + O H 2 hydrazone (not isolated) In lecture, we looked in detail at the mechanism for conversion of the hydrazone intermediate into the final Wolff-Kishner product. The mechanism for formation of this hydrazone via reaction of hydrazine with the ketone starting material
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Unformatted text preview: UNDER BASIC REACTION CONDITIONS is outlined below. Complete this mechanism by drawing curved arrows to show movement of electron pairs, and by drawing structures for each “missing” reaction intermediate. The final intermediate that forms is a resonance hybrid – please draw only the MOST IMPORTANT contributing resonance structure in the box provided. Ph C CH 3 O NH 2 NH 2 OH H OH OH + OH ∆ MORE IMPORTANT RESONANCE STRUCTURE Hydroxide departs as a leaving group - heating is required to overcome the activation barrier (a "strong" base is typically a "poor" leaving group) OH Ph C CH 3 N N H 2 H OH Ph C CH 3 O N NH 2 H H Ph C CH 3 O N NH 2 H Ph C CH 3 O N NH 2 H H Ph C CH 3 N H N H 2...
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