Form A
CH2400 Form A. This Exam has 30 questions, 7 pages.
Look at all possibilities carefully before making your choice.
1. Which of the molecules below are 3˚ alkyl halides?
a.
b.
c.
d.
e.
Compound 3 only
Compound 2 only
Compound 1 only
Compounds 2 and 3
None
2. How many hydrogen atoms does 2-cyclopropylpropane possess?
a.
b.
c.
d.
e.
20
18
16
14
12
3. How many 3˚ carbon atoms are in the molecule below?
a.
b.
c.
d.
0
1
2
3
Cl
4. Which alkyl halide would be least reactive in SN2 reactions?
B.
A.
Cl
C.
D.
Br
I
Br
1
Form A
5. Which of the molecules below is not chiral? (From homework 3.23)
a.
b.
c.
d.
3,3-dimethylpentane
3-chlorohexane
2-iodohexane
1-bromo-2-chlorocyclohexane
Use these structures for the next 2 questions.
CH3CH2 +
CH3O–
OH
NH3
6. How many of the above molecules are electrophiles?
a. 0
b. 1
c. 2
d. 3
e. 4
d. 4
e. 5
7. How many of the above molecules are nucleophiles?
a. 1
b. 2
c. 3
8. Which hydrogens have the greatest electron density? (Based on homework problem 1.40)
a. CH4
b. H2O
c. CH2Cl2
d. HCl
e. SiH4
9. Using the R,S system for indicating absolute configuration place the substituents in descending
order of priority. (Homework problem 3.25)
a.
b.
c.
d.
ClCH2– , CH3CH2– , CH3– , NH2–
NH2– , CH3CH2–, ClCH2–, CH3–
CH3– , ClCH2– , CH3CH2– , NH2–
NH2– , ClCH2– ,CH3CH2– , CH3–
2
Form A
10. In the drawing below which of the labeled bonds is an example of an sp2-sp sigma (σ) bond?
(Use letters given in the structure for your answers).
11. What is the total number of p-p pi (π) bonds present in the structure below?
a.
b.
c.
d.
9
8
7
5
12. In the molecule to the right how many of the labeled
bonds could represent an sp2-sp2 sigma (σ) bond? (Caution!)
a.
b.
c.
d.
e.
Use for questions 10-12
0
1
2
3
4
13. Which of the following generic class is likely to be most nucleophilic?
a.
b.
c.
d.
Weak acids
Strong acids
Carbocations
Conjugate bases of weak acids
14. Which reaction would yield t-butyl alcohol least rapidly? (Based on homework problem 3.29)
a.
b.
c.
d.
e.
1 equivalent of t-butyl iodide with 1 equivalent of water
1 equivalent of t-butyl iodide with 2 equivalents of water
2 equivalents of t-butyl iodide with 1 equivalent of water
2 equivalents of t-butyl iodide with 2 equivalent of water
a and b would be equal and less rapid than c and d.
15. Identify all isomers of 2-methylhexane.
(1)
a.
b.
c.
d.
e.
(2)
(3)
2 only
4 only
1 and 4
1 and 2
all
3
(4)
Form A
16. Which compound(s) below might rearrange if it/they reacted through E1 or SN1. Ignore this for
re-test…too difficult a question. Any similar question will be more straightforward.
Br
Br
Br
Br
(1)
a.
b.
c.
d.
e.
(2)
(3)
(4)
Only 1
Both 1 and 3
Both 2 and 3
1, 2 and 3
All
17. What is the absolute configuration of the molecule below?
a.
R
b. S
Br
C2H5
Cl
H
18. What is the formal charge on the oxygen in the compound below?
a. 0
O-H
b. +1
c. -1
19. Use the structures below to answer this question. The best route to make 2,2-dimethylhexane is:
a.
b.
c.
d.
e.
Convert 2 to an alkyl lithium and allow it to react with 5.
Convert 2 to an organocuprate and react with 1.
Convert 1 to an alkyl lithium and allow it to react with 2.
Convert 1 to an organocuprate and react with 5.
Convert 5 to an organocuprate and react with 4.
Br
Br
Br
(1)
(2)
(3)
Br
Br
Br
(4)
(5)
(6)
4
Form A
20. Are the two molecules shown below identical, constitutional isomers, configurational
isomers, or conformational isomers? Homework question 2.51.
a.
b.
c.
d.
Configurational isomers
Conformational isomers
Identical
Constitutional isomers
21. (Based on homework problem 1.38.). The following four naturally occurring compounds are
carboxylic acids and are therefore weakly acidic, with the pKa values shown. Rank them in order
of decreasing acidity: Formic acid (Ant ‘Venom’), pKa 3.8 Ascorbic Acid (Vitamin C) pKa 4.2
Oxalic Acid (substance making rhubarb bitter) pKa 1.3
Acetic Acid (Vinegar) pKa 4.8
a.
b.
c.
d.
Oxalic Acid
Formic acid
Oxalic Acid
Acetic Acid
>
>
>
>
Ascorbic Acid
Ascorbic Acid
Formic acid >
Ascorbic Acid
> Formic acid > Acetic Acid
> Oxalic Acid > Acetic Acid
Ascorbic Acid > Acetic Acid
> Formic acid > Oxalic Acid
22. What is the best sequence to prepare this molecule:
Br
Br
Br
Br
(1)
a.
b.
c.
d.
e.
(2)
(3)
(4)
Convert 1 to organocuprate and then react that with 3
Convert 3 to organocuprate and then react that with 1
Convert 1 to organocuprate and then react that with 4
Convert 2 to organocuprate and then react that with 4
Convert 4 to organocuprate and then react that with 2
23. What answer correctly ranks the following in order of decreasing acidity:
a. 2,6-difluorocyclohexanol > 2,6-dichlorocyclohexanol > cyclohexanol > 2,6dimethylcyclohexanol
b. 2,6-dimethylcyclohexanol > cyclohexanol > 2,6-dichlorocyclohexanol > 2,6difluorocyclohexanol
c. 2,6-dichlorocyclohexanol > cyclohexanol > 2,6-difluorocyclohexanol > 2,6dimethylcyclohexanol
d. 2,6-dichlorocyclohexanol > 2,6-difluorocyclohexanol > 2,6-dimethylcyclohexanol >
cyclohexanol
5
Form A
24. Which reagents would be best to use to prepare the target compound shown.
a.
b.
c.
d.
2-butanol and bromoethane
ethanol and 2-bromobutane
potassium 2- butoxide and bromoethane
sodium ethoxide and 2-bromobutane
O
25. What is the product of the reaction shown?
(Caution: Look closely)
A potential energy diagram is shown for the reaction of
(S)-3-methyl-3-bromohexane with water to give an
alcohol product. Use this diagram to answer the next 3
questions.
26. What species exists at position 3? (partial charges are not shown in structures)
C2H5
H3C
C
C3H7
A
C2H5
CH3
Br
H
C2H5
O
C3H7
+
H3C
H
C3H7
B
C
C2H5
CH3
H
O
Br
C3H7
H
D
27. Use the selections from question 26 to answer this question. If the product contained only the R
enantiomer what species would account for this?
28. Use the selections from questions 25 amd 26 to answer this question. Assuming an SN1
mechanism what species exists at position 2?
6
Form A
29. Identify all alkenes that are possible products (major and minor) from the reaction of 2-bromo3,4,4-trimethylhexane via E2 using a sterically hindered base.
(1)
a.
b.
c.
d.
e.
(2)
(3)
(4)
1 only
2 only
1 and 2 only
1,2, and 3
All.
30. What product is formed from (S)-2-bromo-3-methylpentane with sodium iodide in DMSO.
a.
b.
c.
d.
(R)-2-iodo-3-methylpentane
(S)-2-iodo-3-methylpentane
a racemic mixture of 2-iodo-3-methylpentane
a racemic mixture of 3-iodo-3-methylpentane
Did you write your Form ID and bubble in your M-Number?
If so….The End.
Please leave quietly and have a good weekend.
7