Week_6.1_PurpleBook_Answers

Week_6.1_PurpleBook_Answers - 142 Acidity of Carbonyl...

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R OR O O H H RO OR O O H H 2. Provide reasonable curved-arrow mechanisms for keto-enol tautomerization in acid and in base: R CH 2 R O RO CH 2 R O NC CH 2 R Acidity of Carbonyl Compounds 1. All of the following compounds have acdic C—H bonds. The pKa of each compound is indicated: Compound pKa 11 13 20 25 31 Conjugate Base O O With each of the above compounds: • identify the most acidic proton of each compound • draw each conjugate base • use resonance structures to show stabilization of the conjugate base • rationalize the acidity order shown • predict and explain the order of nucleophilicity of the conjugate bases 3. The following molecules are both ketones, and are structurally similar. However, they display strikingly different basicity. Explain this observation. pKa = 20 pKa = 40 O OH R O O H RO OR O O H R CHR O CHR O CHR R OR O O RO O O R CHR O RO CHR O CHR H H etc. etc. More resonance: more stable conj.base Ester O is electron donating, which is less stable conj. base.
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This note was uploaded on 05/01/2008 for the course CHEM 51 taught by Professor Gribble during the Spring '08 term at Dartmouth.

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Week_6.1_PurpleBook_Answers - 142 Acidity of Carbonyl...

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