practice_exams_Exam2.pdf
Chemistry 239 with Sasaki at University of Washington - Seattle Campus
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CHEM 239A Summer, 2008 EXAM #2 Name . Prof. Sasaki 150 points TOTAL Good Luck! Note: Only answers in the box wil be graded. _______________________________________________________________________ 1. (35) (a) 4-(N,N-Dimethylamino)pyridine is significantly more basic than pyridine or N,N-dimethylaniline. NN H 3 C H 3 C (i) Circle the most basic nitrogen in the structure of 4-(N, N-dimethylamino)pyridine. (ii) Provide a brief reasoning for your answer in (i). (b) Consider the following esters. C 6 H 5 CO 2 CH 2 CH 3 C 6 H 5 CH 2 CO 2 CH 2 CH 3 HCO 2 CH 2 CH 3 A B C (i) Which ester(s) CANOT undergo the Claisen condensation? (ii) Write the structure of the Claisen condensation product of the ester(s) that CAN undergo the Claisen condensation. CHEM 239A page 2 Name . 2. (40) (a) Draw a step-by-step mechanism for the following reaction. NH 2 NaO 2 H + , 2 O OH + N 2 (b) Show how you would prepare benzylethyldimethylamonium iodide, starting from benzylamine. You may use any reagents that contain 2 carbons or les. NH 2 N H 3 CH 3 OH ? CHEM 239A page 3 Name . 3. (40) (a) Predict the major product(s) for each of the following reactions. If more than one product is expected, please put al of them in the box. (i) H 3 C CH 3 23 N(CH 3 ) OH heat (ii) 2,6-dintroanile 1) NaO 2 , H 2 SO 4 , H 2 O 2) Cul (ii) N O O Br NH 2 - 2 (excs) (b) Consider the following compound, X. H H O O O H H H H (i) Circle the most acidic proton(s) in the structure. (ii) Draw reasonable resonance structure(s) of the conjugate base of the compound X. CHEM 239A page 4 Name . 4. (35) Propose two reasonable syntheses ((a) and (b)) to prepare ethyl-3- phenylpropanoionate, starting from benzyl bromide. Br O O ? Reagents available in your lab: CH 3 -I, ethanol, CH 3 CN, NaOEt/ethanol, KOtBu/tert-butanol, NaOH, Li-N(iso-propyl) 2 , Br 2 , H + , H 2 O, ethyl acetoacetate, diethyl malonate, ethyl acetate, heat. Al the reagents, except for H + and H 2 O, can be used only once. If you have used a reagent in synthesis (a), you are not alowed to use the same reagent in synthesis (b) again. (a) (b) Tomikazu Sasaki Microsoft Word - Chem239A Exam#2.doc
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Dennis
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