Chemistry 30A Spring 2004 Exam 2 Page 1 Questions 1 3 refer to this SN2 reaction Cl CH3 NaI DMF 1 3 points Write the product of this SN2 reaction in the box above 2 4 points Write the mechanism of this SN2 reaction including all transition states 3 3 points By changing only the electrophile rewrite this SN2 reaction so it is obviously faster Include the product but not the mechanism Questions 4 and 5 refer to this SN1 reaction I CH3OH 4 6 points In the box write two major products that might be formed in this SN1 reaction 5 11 points Write the SN1 mechanisms for your two products Do not include any transition states Label the rate determining step s with rds You may use the Ph abbreviation Chemistry 30A Spring 2004 Exam 2 Page 2 Questions 6 8 refer to this E2 reaction CH3 CH3O Cl CH3OH 6 6 points In the box write two E2 products that might be formed in this reaction Label the major product as major 7 4 points Write the E2 mechanism for the major product only Include the transition states 8 2 points Complete this rate expression for the reaction Rate k Questions 9 11 refer to this E1 reaction CH3 OSO2 CF3 CH3OH 9 6 points In the box write two E1 products that might be formed in this reaction Label the major product as major 10 7 points Write the E1 mechanism to show how both of your predicted products are formed Do not include any transition states 11 2 points By changing only the base rewrite this E1 reaction so is obviously slower Include the product but not the mechanism Chemistry 30A Spring 2004 Exam 2 Cl Questions 12 and 13 refer to this reaction Page 3 CH3S DMF 12 2 points Circle the most probable mechanism for this reaction SN2 S N1 E2 E1 13 9 points Briefly explain your choice of reaction mechanism 14 9 points In lecture it was mentioned that regardless of the origin of a carbocation it only reacts in a three ways which we call the three carbocation fates Using the carbocation shown below and CH3OH as the only reactants in each case name and illustrate the three carbocation fates Use curved arrows and show the products of each carbocation fate If the fate can proceed by more than one pathway write only the most favorable pathway Fate 1 Illustration CH3OH Fate 2 Illustration CH3OH Fate 3 Illustration CH3OH Chemistry 30A Spring 2004 Exam 2 Page 4 15 6 points Circle the appropriate answer in each case a Best leaving group CH3SO3 CF3SO3 b Most polar protic solvent Methanol c Most stable carbocation CH3 CF3CH2O Ethanol CF3CH2S DMF CH2OCH3 CH2N CH3 2 16 4 points In CH3OH fluoride is a circle one Good nucleophile Acetone CH2N CF3 2 Poor nucleophile The reason for this is finish the sentence in five words or less 17 2 points Consider this reaction CH3 3CX ROH CH3 3COR ROH is the reaction solvent This reaction is fastest when circle one a R CH3 and X F d R H and X Br b R CH3 and X Br e Rates about equal for all of these cases c R H and X F 18 2 points Consider this reaction RBr CH3OH ROCH3 CH3OH is the reaction solvent This reaction is fastest when RBr is circle one CH3Br Br Br Br 19 2 points Consider this reaction CH3 3C I nuc CH3 3C X This reaction is fastest in DMF when nuc is circle one F Cl Br I Rates about equal Chemistry 30A Spring 2004 Exam 2 Page 5 20 6 points Consider this reaction in which the alcohol is present in large excess i e it is the solvent CH3F CH3 CH2 10CH2OH CH3OCH2 CH2 10CH3 List three distinctly different one sentence reasons why this is not a reasonable SN1 reaction Reason 1 Reason 2 Reason 3 21 4 points Draw a molecule having exactly five carbons and a good leaving group but cannot undergo an E2 reaction In one sentence or less briefly explain your answer Hint Favoring another reaction mechanism does not prevent E2 Molecule Explanation