Chem 14D Exam 1 P 1 1 For each pair of reactions shown below identify the SN2 reaction that will occur more readily a k a PROBLEM SET 1 QUESTION 7 a Circle the faster reaction 5 points Li 1 OTs 2 OTs Li b Circle the faster reaction 5 points 1 CH3I NaOCH3 CH3OCH3 MeOH OR 2 CH3I NaOCH3 CH3OCH3 DMSO 2 Draw the major product of the following reaction sequence 10 points a k a PROBLEM SET 3 QUESTION 1 1 NaH 2 MeOTs O HO Me 3 3 Bromo 1 butene and 1 bromo 2 butene both undergo SN1 reactions at a comparable rate even though one is primary and one is secondary Propose an explanation for this observation 10 points a k a PROBLEM SET 2 QUESTION 5 Br 3 bromo 1 butene Br 1 bromo 2 butene POINTS EARNED ON THIS PAGE Both substrates dissociate to give the same carbocation 30 Chem 14D Exam 1 P 2 4 Based on your knowledge of pKa values rank the following in order of leaving group ability 1 being the best leaving group 4 being the worst leaving group 10 points CH3COO I 1 3 t BuO H2O 4 2 5 Rank the following in order of nucleophilicity 1 being most nucleophilic 4 being the least nucleophilic 10 points NH3 H2O NH4 H2N 2 3 4 1 6 Draw the major product for the following reaction 10 points O OD D NaBD4 EtOD 7 a Predict the major product of the following reaction Answers without stereochemistry will be given no credit 5 points Br O NaH OH DMF b In the space below draw a detailed arrow pushing mechanism for your answer 5 points Br H O H Br O O backside attack stereochemical inversion POINTS EARNED ON THIS PAGE 40 Chem 14D Exam 1 P 3 8 a Which of the following two substrates would likely undergo faster E2 elimination circle your answer 5 points Br Br or Me Me Me Me A B b Provide an explanation for your answer that includes 3 dimensional drawings 5 points Br Br H Me Me H A Me E2 requires antiperiplanar relationship between breaking C H and C Br bonds Me H This is possible in substrate B but not in substrate A B 9 Consider the following solvents For each draw the structure and circle the appropriate solvent classification a DMF 3 points Structure Classification Circle one answer polar protic O H polar aprotic N nonpolar aprotic b Water 2 points Structure Classification Circle one answer polar protic H O H polar aprotic nonpolar aprotic POINTS EARNED ON THIS PAGE 15 Chem 14D Exam 1 P 4 10 Propose a synthesis of compound A beginning from bromobenzene You may also use fragments of 2carbons or less You are encouraged to think about mechanisms and retrosynthetic analysis but it is not necessary to show these in your final answer 15 points Retrosynthesis not necessary to show OH see exam review question 11 for synthesis of this alcohol A an alkene can be made from an elimination reaction SOLUTION OH Br 1 Mg O PCC 2 acetaldehyde OH H2SO4 cat MeMgBr benzene heat A Bonus Draw the product of the following reaction you must show a structure 5 points extra credit O O H NO2 H N NaOH acetone N H O INDIGO POINTS EARNED ON THIS PAGE 20