FINAL EXAM - 200 pts

1. (6 pts) Draw the structure corresponding to the IUPAC names below:

a) (E)-3-methyl-4-bromo-2-pentenol

b) 3,3-dimethylcyclohex-2-en-1-ol

 c) m-bromonitrobenzene

2. (8 pts) MATCH the appropriate hybridization to each indicated atom in the compounds below. Place the latter of your response in the blank to the left of each compound. (2 pts each)

A. sp B. sp2 C. sp3 D. not hybridized

 a)

b)

d) 

 

3. (11 pts) Consider the reaction below to answer the following questions.

a) Indicate both chair conformations of the alcohol by drawing in the substituents on the templates provided below. (4 pts)

 

 

 

b) The configuration at the hydroxyl-bearing carbon in the alcohol is: (2 pts)

A. R

B. Cannot be determined since the carbon is not chiral

C. S

D. antiperiplanar

 

c) On the structures provided below, draw arrows indicating electron flow in the mechanism of the reaction. (5 pts)

 

 

 4. (6 pts) Consider the Newman projections below to answer the following questions. Place the letter of your choice in the blank to the left of the question.

 

a) The most stable conformation of isopentane.

b) A conformation with two gauche interactions.

 5. (8 pts) Prostaglandin F2a is a smooth muscle stimulant used therapeutically as an abortifactant. Consider its structure to answer the following questions.

 

a) Considering only the sp3 stereogenic centers, how many different stereoisomers are possible?

 b) The hybridization of carbon atom A is .

 c) Assign R or S configuration to carbon atom B.

6. (6 pts) Consider the three sugar molecules below to answer the following questions.

a) Compounds X and Y are:

A. identical

B. enantiomers

C. diastereomers

D. meso compounds

b) Compounds X and Z are:

A. identical

B. enantiomers

C. diastereomers

D. meso compounds

 c) Assign R or S configuration to carbon 3 in Compound Y

7. (9 pts) The following multiple choice questions concern nucleophilic substitution and elimination reactions.

Circle the letter of the best choice.

a) Which of the following alkyl halides would have the greatest reactivity in an SN1 reaction?

 

b) E2 reactions compete with SN2 reactions. For the reaction below, choose the base that would give the most E2 product.

c) The nature of the nucleophile has a major effect on the rate of an SN2 reaction. For the reaction below, choose the nucleophile that would react the fastest in a protic solvent.

8. (18 pts) Consider the Friedel-Crafts alkylation reaction below to answer the following questions.

a) Show the electron flow with arrows on the structures provided below for the generation of the carbocation intermediate. (6 pts)

b) (3 pts) The tertiary carbocation generated in the reaction above functions in the Friedel-Crafts reaction as:

A. an electrophile

B. a nucleophile

C. an activating group

D. a deactivating group

c) Write the complete stepwise mechanism for the reaction of benzene with the tertiary carbocation. Show all electron flow with arrows and include all intermediate structures. (6 pts)

d) Which of the following is not a limitation of Friedel-Crafts alkylation reactions? (3 pts)

A. Polyalkylation of the ring occurs.

B. Rearrangements of the alkyl group often occur.

C. Carbocations can only be generated from alkyl halides.

D. Deactivated rings do not undergo Friedel-Crafts reactions.

9. (10 pts) Circle all compounds below which are predicted to be aromatic and draw a big X through those that are not aromatic.

10. (12 pts) Consider the reaction below to answer the following questions.

 

 a) Circle the electrophile in the above reaction.

 b) This reaction is classified as:

A. an addition reaction

B. an elimination reaction

C. a substitution reaction

D. a rearrangement

 c) This reaction will proceed with which of the following types of stereochemistry?

A. retention

B. racemization

C. inversion

D. antiperiplanar

 d) This reaction is expected to proceed by:

A. SN1 mechanism

B. SN2 mechanism

C. E1 mechanism

D. none of the above

 11. (12 pts) Consider the reaction below to answer the following questions.

Reaction of styrene with a dilute solution of bromine in water yields a bromohydrin.

 a) Draw the structure of the intermediate involved in the mechanism of the above reaction.

 b) Is the product chiral? Why or why not?

 c) Is the product optically active? Why or why not?

 12. (5 pts) What is the order of increasing acidity for the following compounds? (least acidic first)?

 A. I, II, III, IV

B. I, IV, III, II

C. III, II, I, IV

D. I, III, II, IV

E. IV, II, III, I

F. III, I, IV, II

 13. (6 pts) Draw all possible resonance structures for the structure below:

(HINT: First redraw the structure showing all hydrogen atoms present)

14. (63 pts, 3 pts each) Predict the major organic products for the following reactions. If more that one product is expected in significant amounts, draw all of them and circle the major product. Show stereochemistry for all reactions marked with an asterisk (*).

*a)

b)

c)

*d)

e)

f)

 

g)

h)

 

i)

 

j)

 

k)

l)

 

m)

 

*n)

 

*o)

 

*p)

*q)

r)

s)

*t)

 u)

 

15. (3 pts) An acid with a low pKa:

A. is a weak acid

B. is a strong acid

C. has a weak conjugate base

D. both b and c

16. (2 pts) The most stable conformation of cis-1,4-dimethylcyclohexane is: (Circle the correct structure)

17. (9 pts) Choose the best set of reagents from the list below for carrying out each of the following conversions. Place the letter of the selected reagent over the reaction arrow.

A. 1. CH3CH2Cl, AlCl3 2. HNO3, H2SO4

B. 1. Br2, FeBr3 2. K2Cr2O7

C. 1. Cl2, FeCl3 2. SO3, H2SO4

D. 1. HNO3, H2SO4 2. CH3CH2Cl, AlCl3

E. 1. KMnO4, NaOH, H2O 2. Br2, FeBr3

F. 1. SO3, H2SO4 2. Cl2, FeCl3

 a)

b)

c)

 18. (6 pts) Write a mechanism (intermediates and arrows) to explain the following reaction. (Be sure to show why the more highly substituted alkene product is not formed.)

Copyright 1988, Kenn Harding