blackwell 343 exam3.fall11

Chem 343 – Fall 2011 EXAM 3 Last Name (print clearly): ____________________________ First Name: ____________________________ • Do not open the exam booklet until 7:15 pm. After that, you have until 8:45 pm to complete this

exam. Make sure you have 12 pages in this exam (4 at the end are scrap paper). • This is a closed book, closed note exam. No calculators are allowed during this exam. You may,

however, use your molecular model kit for this exam. A periodic table is included on the last page of this exam.

• Print your name at the top of page 1 and 2. • There are 9 problems, some with multiple parts. Quickly skim the entire exam before starting

and budget your time wisely for each problem (i.e., do not spend 40 minutes on one problem). • Four pages of blank paper at end and the backs of pages should be used as scrap paper. Final

answers must be written legibly in the space provided. • When showing stereochemistry, make sure that you draw clearly. • Please keep your paper covered and your eyes on your own work. Substantiated evidence for

cheating or other misconduct is grounds for automatic course failure. • GOOD LUCK.

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Last Name (print clearly): ____________________________ First Name: ____________________________

PROBLEM POSSIBLE POINTS

1 /5

2 /5

3 /4

4 /4

5 /4

6 /12

7 /12

8 /30

9 /24

TOTAL PTS = /100

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1. (5 pts) Show the reagents needed to make the following ether using the Williamson ether synthesis.

O

2. (5 pts) Show the reagents needed to make the following ether using the alkoxymercuration-reduction method.

O

+ enantiomer 3. (4 pts) Circle the predominant product formed in the following reaction.

4

4. (4 pts) Circle the reagents necessary for the following transformation.

A. HBr, in the dark B. HBr/peroxides C. 1.) CH3O- /CH3OH, 2.) HBr, dark D. 1.) CH3O- /CH3OH, 2.) HBr/peroxides E. 1.) (CH3)3CO- /(CH3)3COH, 2.) HBr/peroxides

5. (4 pts) Circle the reagents necessary for the following transformation:

A. HCl B. SOCl2/Base C. 1.) TsCl/Base, 2.) Cl- /DMSO D. 1.) TsCl/Base, 2.) I-/DMSO, 3.) Cl-/DMSO E. All of the above would work about equally well.

6. (4 pts each) (a) Circle the strongest acid. Put a box around the weakest acid:

SH NH2 OH H H

(b) Circle the strongest base. Put a box around the weakest base:

HH H

H

- NH2 - OH

(c) Circle the alkyl halide that will react most rapidly with propanol:

I Cl BrBr

5

7. (12 pts) Provide a mechanism that accounts for the following product. Show all intermediates, formal charges, and use the curved arrow notation.

HO

Br2

H2O

O Br

6

8. (5 pts each = 30 pts) For each of the following six reactions, draw the structure of the major product. If the major product is one specific stereoisomer, be sure to show the correct one. If the major product is formed as equal (or approximately equal) amounts of two or more different compounds, clearly indicate which ones are formed. It is acceptable to clearly draw one enantiomer and then simply state “+ enantiomer”.

1. Cl2, H2O

2. NaH, THF3. H3O+, H2O

A

B

C CrO3, HCl/pyridine (excess)OH

OH

1. CH3COOOH

2. NaSCH3, DMSO3. H3O+

D

1. Hg(OAc)2, H2O2. NaBH4, NaOH, H2O

3. MsCl, pyridine4. NaCN, DMF

E

3. O34. S(CH3)2

OH

1. SOCl2, pyridine2. (CH3)3CO-, (CH3)3COH

F

HOCH2Cl2

O 1. HCl, 100 °C

2. NaOCH3, HOCH3

7

9. (4 pts each = 24 pts) For each of the following reactions, provide reagents over/under the arrow that would convert the reactant shown to the product shown as a major product. Your reagents may include alkyl halides, acids, bases, nucleophiles, oxidants, catalysts, and solvents. More than one step is required for each. Number the steps sequentially as 1, 2, 3…., etc. Note, a shorter number of feasible steps is always preferred over a longer, extremely cumbersome sequence that gives the same product.

C

D

E

F

IO

HO

+ enantiomer

O

B

O

O

O

OH NH2

HABr

8

9

10

11

12