KEY Pre#4-251-06 - ORGANIC CHEMISTRY LECTURE CHY 251(02)...

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ORGANIC CHEMISTRY LECTURE CHY 251(02) Prelim IV, 12/07/06 _______ KEY _______ I. Each of the following multiple choice questions has one correct answer. (3pts/each) 1. An S N 2 displacement is carried out on the pure compound shown below. The product will be a(an) _ _ _ _ _ . (Hint. Carefully work out this problem before answering.) a) pure enantiomer b) optically active compound c) meso compound d) structural isomer 2. Which one of the following is a correct statement about nucleophilic substitution occurring by an S N 1 mechanism? a) Doubling the concentration of nucleophile does not change the rate of reaction. b) Solvents with high dielectric constants help stabilize the intermediate carbocation. c) 1-Chloro-1-phenylethane reacts faster than sec -butyl chloride with water. d) The rate-determining step involves ionization of a carbon to leaving group bond. e) All of the above are correct. 3. The rate law for the following reaction is: CH 3 -CH 2 -CH 2 -CH 2 -Cl + NaCN DMF a) rate = k[CH 3 CH 2 CH 2 CH 2 -Cl] b) rate = k[CH 3 CH 2 CH 2 CH 2 -Cl][NaCN] c) rate = k[CH 3 CH 2 CH 2 CH 2 -Cl] 2 [NaCN] d) rate = k[NaCN] . 4. Which one of the following alkynes affords a single product from the acid-catalyzed addition of water ? a) 2-Pentyne b) 2-Hexyne c) 3-Heptyne d) 3-Hexyne OCH 3 H 3 C H H 3 C H Br CH 3 O - S N 2
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5. How many products , including E/Z isomers, can be formed from the E1 dehydration below? heat H 3 PO 4 H 3 C H 2 C C H 2 C H 3 C OH ? a) 1 b) 2 c) 3 d) 4 e) 5 f) 6 6. Which one of the nucleophiles listed would afford an S N 2 product most rapidly ? CH
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This test prep was uploaded on 04/18/2008 for the course CHY 251 taught by Professor Jensen during the Fall '06 term at University of Maine Orono .

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KEY Pre#4-251-06 - ORGANIC CHEMISTRY LECTURE CHY 251(02)...

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