2010 final exam practice-chap 11-12 - Department of Chemistry

ILLINOIS STATE UNIVERSITY 

Dr. Hitchcock, Department of Chemistry, Illinois State University 

Organic Chemistry Examination I 

Page 1 

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Total 

______/ 8 pts 

______/10 pts 

______/10 pts 

______/20 pts 

______/20 pts 

______/21 pts 

______/11 pts 

______/100 pts 

Name (Print):___________________________________ 

Last 4 digits of Student Number:___________________ 

This practice Exam is the intellectual property of prof. S. R. Hitchcock and should be used for educational purposes. 

© 2010, Prof. S. R. Hitchcock, Ph.D., Department of Chemistry, Illinois State University 0

PART I 

MULTIPLE CHOICE 

Write the best choice in the space that is provided. (8 pts total) 

1. Which of the following reactions would most likely involve carbocations (1.5 pts) 

(a) cyclohexene reacting with ozone 

(b) cyclohexene reacting with BH 3 and NaOH/H 2 O 2 

(c) cyclohexene reacting with HCl 

(d) cyclohexene reacting with HBr and peroxides 

2. Which reaction most likely occurs with syn-stereospecificity (1.5 pts) 

(a) alkene reacting with HBr 

(b) alkene reacting with HBr and peroxides 

(c) bromination in carbon tetrachloride (CCl 4 ) 

(d) alkene reacting with BH 3 and NaOH/H 2 O 2 

3. Which one of the following carbocation rearrangements would be unlikely (1.5 pts) 

(a) primary → secondary 

(b) secondary → tertiary 

(c) primary → tertiary 

(d) secondary → primary 

4. Which of the following reactions would be considered to be anti-Markovnikov in terms of the 

regiochemistry (1.5 pts) 

(a) alkene reacting with diatomic bromine (Br 2 ) in CCl 4 

(b) alkene reacting with HBr in the absence of peroxides 

(c) alkene reacting with HBr in the presence of peroxides 

(d) alkene reacting with diatomic bromine (Br 2 ) in water (H 2 O) 

5. Which set of reagents would be suitable to induce the following transformation without 

rearrangement of the carbon structure Note that the stereochemistry is not a concern in this 

transformation. (2 pts) 

CH 2 

 

CH 3 

H 

HO 

H 

(a) BH 3 and NaOH/H 2 O 2 

(b) Hg(OAc) 2 , H 2 O; NaBH 4 

(c) catalytic sulfuric acid and H 2 O 

(d) HBr followed by nucleophilic displacement with water (H 2 O) 


PART II 

SHORT ESSAYS IN O. CHEM. 

1. Show the first reactive intermediate that forms in each of the following reactions and state which 

reaction follows Markovnikov regioselectivity and which is anti-Markovnikov regioselectivity. 

(2 pts each/4 pts total) 

CH 3 

H 

HBr, heat 

peroxides 

CH 3 

HBr, 0 o C 

H 

2. What is the origin of the regioselectivity and stereochemistry in the electrophilic addition of an 

acid to an alkene (1 pt) 

3. Provide two solid reasons why synthetic organic chemists tend to avoid reactions involving 

carbocations (1 pt). 

4. Consider the reagents that are listed below. Stereochemistry is always a concern when such 

reagents are employed with alkenes. Fill in the chart below using stereochemistry terms such as 

either, anti-stereospecific, syn-stereospecific or poor stereoselectivity. 

(4 pts total) 

Reagent 

BH 3 and NaOH, H 2 O 2 

HBr 

Stereochemistry 

OsO 4 ; NaHSO 3 

Br 2 in CH 3 OH 


5. Your assistant, Ronald M c Dingleberry, has set up a reaction to achieve a hydration of an alkene 

but it does not give any product. What is the explanation for the failure of this reaction (1 pt) 

CH 2 CH 3 

H 2 O 

6. What is wrong with the answer that is listed for the following reaction (1 pt) 

H 

CH 3 CH 3 

HCl 

H 

Cl 

H 

7. Consider the following mechanistic step. Is this depicted correctly If not, explain the nature of 

the problem. (1 pt) 

H 

CH 3 

H 

8. Consider the addition of hydrogen bromide to cyclopentene. Provide a solid argument for why the 

cis- and trans-addition products are observed. (3 pts) 

HBr 

H 

Br 

+ 

H 

Br 

9. Draw out the products for the following reactions and determine if a mixture of isomeric 

compounds form or if a meso-compound forms. (2 pts each/4 pts total) 

(a) 

H 

CH 3 

CH 3 

H 

Br 2 

CCl 4 

H 

(b) 

H 3 C 

H 

CH 3 

Br 2 

CCl 4 


PART III 

MECHANISMS IN ORGANIC CHEMISTRY 

1. Provide the products and a detailed reaction mechanism that are listed below. Identify at least one 

nucleophile and electrophile. The mechanism must be drawn out completely. Draw the 

mechanism on the back of the preceding page. (4 pts each/12 pts) 

A. 

H 

Br 

H 

NaOCH 3 in CH 3 OH 

HBr 

60 o C 

B. 

Br 2 

CH 3 OH 

CH 3 cat. H2 SO 4 

C. CH 3 

D. CH 2 

H 2 O 

2. Provide an explanation for the observed product that forms in the following reaction. Complete 

this problem by showing a reaction mechanism. What name is given to this process Draw the 

mechanism on the back of the next page. (4 pts) 

H 3 C 

CH 3 H 

C C CH 2 

CH 3 

cat. H 2 SO 4 

H 2 O 

heat 

H 3 C 

OH 

C CH 

CH 3 

CH 3 

CH 3 

3. Complete the mechanism for the following transformation. (2 pts total) 

CH 3 

CH 3 

H 

CH 3 

CH 2 

4. Draw the critical intermediate that forms when cyclohexene is exposed to osmium tetroxide 

(OsO 4 ) and when cyclopentene is exposed to ozone (O 3 ) in CH 2 Cl 2 (1 pt each/2 pts total) 


PART IV 

SYNTHETIC ORGANIC CHEMISTRY 

Complete the following reactions by drawing the major and minor products. If there is no reaction, then 

write NR. You must address any stereochemistry involved in the reactions. (2 pts each/20 pts total) 

CH 2 CH 3 

HCl 

Et 

OH 

H 3 PO 4 

heat 

CH 3 

CH 3 

H 2 (g), Pd 

ethanol 

OsO 4 

NaHSO 3 

Et 

H C 3 H 7 

Br 2 

CCl 4 

m -CPBA 

(RCO 3 H) 

CHCl 3 

cat. H 2 SO 4 

H 2 O 

1. O 3 

2. Zn 

CH 2 CH 3 

H 

1. B 2 H 6 -THF 

2. NaOH, H 2 O 2 

Br 2 

EtOH (CH 3 CH 2 OH) 


Br CH 3 

1. NaOCH 3 , heat 

PART V 

SYNTHETIC ORGANIC CHEMISTRY 

1. Complete the following reactions by showing the major product of each transformation. If there is 

no reaction, then write NR. You must address all stereochemical concerns. 

(3 pts each/21 pts total) 


Br CH 3 

2. CH 2 N 2 , heat, hν 

1. HBr 


Cl 

1. KOCH 2 CH 3 , heat 

2. Br 2 in CCl 4 

Br 

1. KOt-Bu, heat 

[KOC(CH 3 ) 3 ] 

2. Hg(OAc) 2 , H 2 O; 

NaBH 4 

2. BH 3 ; NaOH, H 2 O 2 

Cl CH 3 


2. cat. H 2 SO 4 in water 

I CH 3 

[KOC(CH 3 ) 3 ] 

1. KOt-Bu, heat 

2. CHCl 3 , KOt-Bu 


PART VI 

RETROSYNTHESIS 

1. Provide the reagents that are necessary to complete the following reaction sequences. 

(1 pt each/5 pts total) 

Br 

Br 

CH 2 

H 

CH2 OH 

CH 2 

OH 

CH3 

OH 

OH 

2. Provide the reagents that are necessary to complete the following reaction sequences. 

(4 pts total) 

BrCH 3 

CH 3 

OH 

CH 3 

Br 

3. Provide the structure of the starting materials that yielded the following alkenes. (2 pts) 

O 

O 3 ; Zn 

O 

H 

+ ZnO

2010 final exam practice-chap 11-12 - Department of Chemistry

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