Reviewquestions_22

Reviewquestions_22 - 1) Show how an enolate can add to a...

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1 1) Show how an enolate can add to a carbonyl. Answer: Diff: 1 2) Provide a detailed, stepwise mechanism for the base-catalyzed enolization of acetaldehyde. Answer: Diff: 1 3) Provide a detailed, stepwise mechanism for the acid-catalyzed enolization of acetaldehyde. Answer: Diff: 1 4) The relationship between ketones and their corresponding enols is one of: A) allotropes. B) tautomers. C) enantiomers D) diastereomers. E) cis-trans isomers. Answer: B Diff: 1 6) When a ketone and its enol are in equilibrium, under most conditions the concentration of the enol is __________ the concentration of the ketone. A) slightly higher than B) equal to C) much higher than D) much lower than E) exactly half of Answer: D Diff: 2 7) Which of the following reagents will quantitatively convert an enolizable ketone to its enolate salt? A) lithium hydroxide B) lithium diisopropylamide C) methyllithium D) diethylamine E) pyridine Answer: B
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2 Diff: 1 8) The α -halogenation of cyclohexanone: A) is catalyzed by base. B) is slowed by the presence of acid. C) requires one equivalent of base. D) requires one equivalent of acid. E) is catalyzed by the sodium halide salt. Answer: C Diff: 2 9) Provide a detailed, stepwise mechanism for the a-bromination of acetone in base. Answer: Diff: 2 11) Provide a detailed, stepwise mechanism for the formation of acetate and bromodiiodomethane from bromoacetone, hydroxide and iodine. Answer: Diff: 3 13) When aldehydes are subjected to the same conditions that α -halogenate ketones (i.e., X 2 and aqueous acid or base), they are: A) α -halogenated as well. B) reduced to alcohols. C) converted to the acid halide. D) oxidized to the acid or carboxylate. E) esterified. Answer: D Diff: 2
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3 14) The Hell-Volhard-Zelinsky reaction involves: A) the α -bromination of carboxylic acids. B) the α -bromination of ketones. C) the bromination of alcohols. D) the oxidation of aldehydes to acids. E) none of the above. Answer: A Diff: 1
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4 15) Provide a mechanism for the following reaction: butanoic acid + Br 2 + PBr 3 2-bromobutanoyl bromide Answer: Diff: 3 16) Provide the sequence of synthetic steps required to produce N -cyclohexyl-2-bromopropanamide from propanoic acid. Answer: 1. PBr 3 , Br 2 2. cyclohexylamine Diff: 3 17) Which of the following will alkylate a lithium enolate most rapidly? A) methyl bromide B) isopropyl bromide C) neopentyl bromide D) bromobenzene E) 2-methylbromobenzene Answer: A Diff: 2 18) What are the two key resonance structures for an enamine? Label the major and minor contributors. Answer: Diff: 2
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5 19) What iminium salt is produced in the reaction shown below? Answer: Diff: 2 20) Methylamine reacts with acetophenone to yield the: A) iminium salt. B) imine.
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This note was uploaded on 03/18/2010 for the course DSAG asdg taught by Professor Asdg during the Spring '10 term at 東京国際大学.

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Reviewquestions_22 - 1) Show how an enolate can add to a...

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