Alkenes contain the unsaturated C=C functional group which characteristically undergo addition reactions. This is driven by the conversion of the weaker π bond into 2 new, stronger σ bonds. The reactions of alkenes can seem a little bewildering as a wide variety of reagents undergo this type of reaction providing access to products with various regioselectivities and stereoselectivities depending on the reagent and / or reaction conditions, but ultimately on the mechanism by which the reaction occurs. There are potentially 3 factors associated with each of the addition reactions of alkenes: • overall transformation (i.e. C=C to what functional group) • regioselectivity (provided the two atoms that add are different) • stereoselectivity (most easily revealed with cyclic alkenes

1. Chapter 6 Reactions of Alkenes Addition Reactions

2. • 1. Which one of the following is not a metal
catalyst for the hydrogenation of an alkene?
•
•
•
•
A.
B.
C.
D.
Pd
Pt
Na
Ni

3. • 2. What is(are) the product(s) in the Pdcatalyzed hydrogenation of 1,2dimethylcyclopentene?
• A. trans-1,2-dimethylcyclopentane
• B. cis-1,2-dimethylcyclopentane
• C. a mixture of trans and cis-1,2dimethylcyclopentane
• D. 1,1-dimethylcyclopentane

4. • 3. Which of the following alkenes is expected
to have the highest heat of hydrogenation?
•
•
•
•
A.
B.
C.
D.
1-pentene
trans-2-pentene
cis-2-pentene
2-methyl-2-butene

5. • 4. Which alkene below is thermodynamically
the most stable?
•
•
•
•
A.
B.
C.
D.
1-hexene
trans-3-hexene
cis-3-hexene
2-methyl-2-pentene

6. • 5. The stereochemical pathway for the
hydrogenation of an alkene with a metal catalyst,
such as platinum, occurs via
•
•
•
•
•
A.
B.
C.
D.
syn addition.
anti addition.
Markovnikov addition.
anti-Markovnikov addition.

7. • 6. The product(s) in the following reaction
is(are)
•
•
•
•
A.
B.
C.
D.
only trans-1-4-dimethylcyclohexane.
only cis-1-4-dimethylcyclohexane.
both trans and cis-1-4-dimethylcyclohexane.
methylcyclohexane.

8. • 7.
What is the major product of the following reaction?
•
•
•
•
A
B
C
D
A.
B.
C.
D.

9. • 8. Predict which of the following alkenes
reacts the fastest with HCl?
•
•
•
•
A.
B.
C.
D.
CH3CH2CH2CH2CH=CH2
cis-CH3CH2CH=CHCH2CH3
trans-CH3CH2CH=CHCH2CH3
(CH3)2C=CHCH2CH3

10. • 9. Which reagent(s) below would work best in
converting 2-methyl-2-hexene to 2-methyl-3hexanol?
•
•
•
•
•
A.
B.
C.
D.
(1) H2SO4
(2) H2O
50% H2SO4/H2O
(1) BH3/THF
(2) H2O2, NaOH
Br2/H2O

11. • 10. The hydroboration-oxidation reaction can be
characterized as the ___________________ to an
alkene.
•
•
•
•
•
A.
B.
C.
D.
anti-Markovnikov syn addition of water
anti-Markovnikov anti addition of water
Markovnikov syn addition of water
Markovnikov anti addition of water