CHEM Fall Exam 2 Professor R. Hoenigman. Signature. Name (printed) Last four digits of your student ID number.

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1 Average = 68 I pledge to uphold the CU on Code: CEM Fall 2006 Exam 2 Profess R. oenigman igh = 98 Low = 18 Signature Name (printed) Last four digits of your student ID number Recitation TA Recitation number, day, and time You have 1 hour and 30 minutes to complete this exam. No model kits calculats allowed. Periodic table and scratch paper are attached. D NT TURN TIS PAGE UNTIL INSTRUCTED T D S. Recitation Sections: # Day Time TA 211 Monday 8 am Noel 251 Monday 2 pm Carolynn 291 Monday 5 pm eather 252 Tuesday 12 pm Sam 293 Tuesday 5 pm Carolynn 212 Wednesday 8 am Noel 253 Wednesday 1 pm Tom 292 Wednesday 5 pm eather 213 Friday 8 am eather Sce: Page 1 /21 Page 2 /14 Page 3 /15 Page 4 /15 Page 5 /15 Page 6 /20 TTAL /100

2 CEM 3311, Fall 2006 Exam 2, page 1 of 8 1. (12 pts) Naloxone (shown below) has a structure that is similar to heroin. In fact, naloxone is often used to reverse a heroin overdose. Circle all of the terms below that describe one me structural feature of naloxone. (2 points each circle, -1 point increct circle) Amine Alkene Aldehyde Amide Ester Aromatic ring Alcohol Ether Ketone N Naloxone 2. (9 pts) F each of the following pairs, circle the compound that has the lower heat of combustion. In the box, give a brief reason f your choice. (1 point each circle, 2 points explanation) A. cis -2-methylcyclohexanol Both substituents are equatial. trans-2-methylcyclohexanol Book Problem 4.25 B. cis -3-methylcyclohexanol trans-3-methylcyclohexanol Both substituents are equatial. Book Problem 4.25 C. (E)-cyclopentene (Z)-cyclopentene In a cycloalkane of less than 10 carbons, the Z isomer is me stable.

3 CEM 3311, Fall 2006 Exam 2, page 2 of 8 3. (6 pts) Which reactions in the following pairs will take place me rapidly? Circle your answer. In the box, give a brief reason f your choice. (1 point each circle, 1 point explanation) A. 2 alcohols react faster than 1 alcohols when reacted with a hydrogen halide. Book Problem 4.37a B. I I I is me reactive towards an alcohol than. C. 1-cyclopentylethanol 1-ethylcyclopentanol 1-bromo-1-ethylcyclopentane 1-bromo-1-ethylcyclopentane 3 alcohols react faster than 2 alcohols when reacted with a hydrogen halide. Book Problem 4.37b (see page 7 f these structures) 4. (8 pts) Write an arrow pushing mechanism f the preparation of methyl bromide from methanol and hydrogen bromide. In the box below, state whether this is an S N 1 S N 2 reaction. Book Problem 4.40 S N 2 (-5 points if an S N 1 mechanism is drawn) C 3 3 C C (2 point arrows) (1 point -, 1 point C ) (1 point water) (1 point C 3 )

4 CEM 3311, Fall 2006 Exam 2, page 3 of 8 5. (15 pts) Menthyl chlide and neomenthyl chlide have the structures shown below. ne of these stereoisomers undergoes elimination on treatment with sodium ethoxide in ethanol much me readily than the other. C(C 3 ) 2 C(C 3 ) 2 3 C 3 C Menthyl chlide Neomenthyl chlide Book Problem 5.41 A. Using arrows to show the flow of electrons, draw a mechanism to account f the dehydrohalogenation of each of the isomers. Be sure to draw neat chair cyclohexanes. (5 points each mechanism) Menthyl chlide: C 3 C(C 3 ) 2 C(C 3 ) 2 3 C + C 3 C 2 + C 3 C 2 ( 4 points, must be anti-periplanar) ( 1 point products) Neomenthyl chlide: C 3 C 2 C(C 3 ) 2 3 C C(C 3 ) 2 3 C + C 3 C 2 + ( 4 points, must be anti-periplanar) ( 1 point products) B. Which reacts faster, menthyl chlide neomenthyl chlide? Why? (2 points f crect isomer, 3 points f explanation) Neomenthyl chlide reacts faster than menthyl chlide in an E2 reaction because the most stable confmation of neomenthyl chlide has the necessary anti-periplanar geometry. Menthyl chlide must first chair flip to a higher energy confmation to achieve the anti-periplanar transition state, thus raising the activation energy (and slowing the rate) of the reaction.

5 CEM 3311, Fall 2006 Exam 2, page 4 of 8 6. (15 pts) Give the single maj ganic product of the following reactions. (3 points each) A. Book Problem 5.32e NaMe 2-bromo-3-methylpentane B. Book Problem 5.38b I KC(C 3 ) 3 (C 3 ) 3 C, Δ C. Book Problem 4.36c D. Book Problem 6.26e dil. 2 S 4 E. Book Problem 6.28i C 3 1-methylcyclohexene + C 3 C

6 CEM 3311, Fall 2006 Exam 2, page 5 of 8 7. (15 pts) Propose reagents f accomplishing the following transfmations. The desired product should be the maj product of the reaction. (3 points each) A. C 3 2 (1 pt) C 3 C 2 (2 pts) (-1 pt if separate steps) C 2 C 3 B. Book Problem 6.32e 3-ethyl-2-pentene 1) B 3 TF 2), (-1 pt if not separate steps) 3-ethyl-2-pentanol C. cyclohexene 1) s 4 (2 pts) cis-1,2-cyclohexadiol 2) (1 pt) D. 2 S 4 E. (Z)-3-methyl-3-hexene (no = no credit) 3-bromo-4-methylhexane

7 CEM 3311, Fall 2006 Exam 2, page 6 of 8 8. (20 pts) Propose an efficient synthesis f the following transfmations. You may use any reagents you like. (-2 points f each unnecessary step) A. cyclohexane starting from bromocyclohexane (6 points) C 3 (any strong base) 2 Pt B. tert-butyl iodide starting from isobutyl iodide (6 points) Book Problem 6.36g I C 3 I I (any strong base) C. (8 points) from a cycloalkane 2 hν (no credit f 2 ) C 3 (any strong base) 1) 3 2) 2, Zn

8 CEM 3311, Fall 2006 Exam 2, page 7 of 8 Structures from problem 3c: Scratch Page 1-cyclopentylethanol 1-ethylcyclopentanol

9 CEM 3311, Fall 2006 Exam 2, page 8 of 8 Scratch Page