ALKENES PROBLEMS
NOMENCLATURE
1.
Give IUPAC names for the compounds represented by the following structural formulas.
a)
H3C
CH2CH3
C
C
CH3
C
H
CH3
CH3
b)
e)
H3C
CH3C(CH3)2CH
C(CH3)2
CH3
f)
2.
C
CH2
H
H
c)
CH3
d)
(CH3)2C
CH
CH2
CH
CHCH3
Draw structural formulas for the following names.
a)
trans-3-hexene
f)
3-methyl-1-pentene
b) cis-2,3,4,5-tetramethyl-3-hexene
g) 3-isopropylcyclohexene
c)
h) (Z)-1-bromo-1,2-difluoroethene
ethylene
d) propylene
i)
(E)-1-chloro-3-ethyl-4-methyl-3-heptene
e)
j)
cis-4-chloro-2-pentene
trichloroethylene
page 1
ALKENES PROBLEMS
3.
Name the following alkenes
a)
f)
CH2
b)
g)
c)
h)
i)
d)
j)
e)
4.
Draw structures of the following compounds
a)
(3Z)-1,3-pentadiene
b) (3E)-1,3-pentadiene
c)
(E)-2,5-dibromo-3-ethyl-2-pentene
d) 2,3-dimethylcyclohexene
e)
3-t-butyl-2-isopropylcyclopentene
f)
1-isobutyl-3-sec-butyl-1,4-cycloheptadiene
g) cis-3,4-diethylcyclohexene
h) 2,5-dimethyl-1,3-cyclopentadiene
page 2
ALKENES PROBLEMS
5.
Which is more stable? Draw their structures and circle the more stable compound.
a)
1-ethylcyclohexene or 3-ethylcyclohexene
b) (Z)-2-butene or (E)-2-butene
c)
6.
2-pentene or 2-methyl-2-butene
State Markovnikov’s rule ………………………………………………………………………………………….
……………………………………………………………………………………………………………………..
7.
Draw and name the structures of the major products of the following reactions.
a)
CH3
HCl
CH3
b)
C
CH2
CH
CH2
CH3
KI
H3PO4
c)
H3C
8.
HBr
Draw and name the alkene reagent that would produce the following product.
CH3
a)
HBr
?
CH3
C
CH2
CH3
Br
b)
?
HCl
CH2CH3
Cl
9.
When treated with KI in H3PO4, vinylcyclohexane produces 1-ethyl-1-iodocyclohexane. Draw the mechanism
for the reaction (showing intermediates and products). Note that drawing a mechanism involves pushing
electrons using arrows.
page 3
ALKENES PROBLEMS
10. Calculate the number of degrees of unsaturation in each of the following
O
CH
CH2
CHCl
CH
C
NH2
11. Calculate the number of degrees of unsaturation in each of the following and draw a possible structure.
a)
C2HCl3O
b) C3H6O2
c)
C4H7NO
12. Elimination reactions can produce mixed products. This is usually undesirable. Draw and name all the
elimination products formed in the following reactions. Identify the major products where possible.
CH2CH3
I
KOH in ethanol
OH
H3C
C
CH2
CH3
H2SO4
in THF, D
CH3
13. Draw the complete mechanism (including any intermediates) for the addition of I 2 (in CCl4 solvent) to
cyclopentene and name the product indicating its geometry.
page 4
ALKENES PROBLEMS
14. State Zaitzev’s Rule: ………………………………………………………………………………………….. .
15. When Br2 water is added to 2,3-dimethyl-2-butene, a mixture of vic dihalide and halohydrin form. Draw a
mechanism for both reactions. Which one is the major product? Why?
16. When concentrated H2SO4 is added to cyclohexene, a bisulfate is formed, however, when aqueous H 2SO4 is
used, an alcohol results. Draw the mechanism for these and give the reason for the difference.
17. Draw the structure of the normal, ‘Markovnikov’ product formed when H-X (where X is a halogen) is reacted
with 1-butene.
18. When peroxides are present, e.g., H2O2, the antiMarkovnikov product forms, but only with H-Br. Draw a
mechanism for this free radical addition reaction with 1-butene. Hint: Br adds first.
page 5
ALKENES PROBLEMS
19. Draw the product (showing its stereochemistry) when cyclopentene is oxidized by cold, neutral or alkaline
KMnO4.
20. In the following table, the alkenes in the left column are oxidized by the oxidants shown in the top row. Draw
the structures of the products of oxidation in the empty cells.
hot KMnO4
CH3
H
CH3
21.
O3, then Zn in dil. CH3COOH
CH
CH2
Draw structures of the main products of the following reactions.
1. Hg(OAc)2, THF, H2O
2. NaBH4
CH3
CH3
C
CH
CH2
dilute
H2SO4
H
1. BH3, THF
2. H2O2, OH-
page 6
ALKENES PROBLEMS
22. Draw structures or structural formulas of the products of the following reactions. In some cases more than one
product may result. Show all the major products
Br
a)
H3C C
KOH
CH2
CH2
in ethanol
CH3
CH3
CH3
b)
CH3
CH2
CH
1.
BH3
2.
H2O2 , OH-
C
CH3
CH2
cold, neutral, KMnO4
show products all products including
those of KMnO 4
c)
CH2CH3
H2C C
CH3
hot, acidic KMnO4
d)
CH2CH3
HBr, H2O2
H2C C
CH3
show only major product and its geometry
e)
HOCl or
Cl2 , H2O
CH3
CH3
f)
CH3
CH2
CH
HCl
C
CH2
g)
CH3
C
CH3
1.
CH3
O3
2. Zn , CH3COOH
page 7
ALKENES PROBLEMS
h)
H3C
Br2 , H2O
C
CH
H3C
i)
1.
BH3
2.
H2O2 , OH-
CH3
23. Draw structures of the following:
a)
methyl group
g) ethylene group
b) methyl chloride
h) ethylene chloride
c)
i)
vinyl group
d) methylene chloride
j)
vinyl chloride
e)
ethyl group
k) vinylidene group
f)
ethyl chloride
l)
methylene group
vinylidene chloride
24. Draw structures of
a)
allyl group
b) allyl chloride
page 8
ALKENES PROBLEMS
25. Name the following compounds including all cis- and trans- isomers where possible.
a)
CH2=CCl2
c)
b) CH2=CHCl
26.
CHCl=CHCl
d) CBrCl=CHCl
State the conditions (temp., pressure and catalyst) required to reduce alkenes with H 2 gas.
…………………………………………………………………………………………………………….
27.
Write an equation showing the reduction of 1,3-butadiene with H2 gas. Include catalyst and conditions.
28. Draw the structure of the alkenes that would produce the following products when treated with O 3, followed by
dilute aqueous CH3COOH.
a)
CH3COCH3
+
CH(CH3)2CHO
b) CH3CH2CHO only (2 moles of product per mole of reagent)
page 9
ALKENES PROBLEMS
29. Three rapid qualitative lab tests are commonly used to identify alkenes. Baeyer’s test (cold, weakly acidic,
dilute KMnO4 solution), the Bromine test (2% Br2 in CCl4 or in water), and the Sulfuric Acid test (using
concentrated H2SO4). Briefly explain what a positive test would look like and explain why.
CH3
H
30. Write structural formulas of the major products forming when 1-methylcyclopentene reacts with each of the
following reagents. Show stereochemistry where cis- and trans- isomers form.
a)
HI
f)
Br2 in CCl4
b) H2/Pt
g) Br2 in H2O
c)
h) cold, dilute KMnO4
dilute H2SO4, warm
d) cold, concentrated H2SO4
i)
O3, then Zn in dil. CH3COOH
e)
j)
KMnO4, OH-, and heat
cold, concentrated H2SO4, then H2O & heat.
k) BH3, then H2O2 and OH- (pH8).
page 10
ALKENES PROBLEMS
31. List all reagents needed to synthesize the following products from 2-methylpropene (isobutylene).
CH3
H3C
C
CH3
CH3
Br
H2C
C
H3C
CH3
C
CH3
OH
H3C
H
OH
H3C
H3C
C
C
CH2Cl
CH2OH
H3C
H3C
32. Outline a synthesis for each of the following products from the starting reagents shown. More than one step may
be necessary. List all reagents needed but mechanisms are not required.
a)
Br
?
OH
b)
H3C
Br
H3C
OH
OH
?
Cl
CH3
c)
CH3
?
I
OH
CH3
d)
CH2
OH
CH2
CH
OH
CH3
CH
CH
?
CH3
H3C
CH3
page 11
ALKENES PROBLEMS
?
e)
CH3
CH
CH3
CH3
CH2
CH3
Br
f)
Br
Br
CH3
?
CH
CH2
CH3
CH2
CH3
OH
g)
?
OH
33.
OH
Draw and name the products of the following reaction indicating which is major and which is minor.
Cl2
CH2
CH
CH
CH2
34. Draw structures of
a)
isobutylene
b) isoprene
page 12
ALKENES PROBLEMS
35. Write the products of the following oxidation reactions, then balance the redox equations.
a)
hot alkaline
KMnO4
CH3
b)
CH3CH
H2CrO4
C
CH3
page 13
ALKENES PROBLEMS
36. Balance the following half reactions and identify them as being either oxidation or reduction.
a)
(in alkaline media)
O
O
CH3CH2CH
CH3CH2COH
O
b) (in neutral media)
c)
(in acidic media)
CH3CHCH2CH2OH
OH
MnO4- 
d)
HNO3  NO2
e)
HIO4  HIO3
f)
(in alkaline media)
g)
Cl2  2Cl-
CH3CCH2COH
O
Mn+2
H2O2  2O-2
page 14