Chapter 5 – Practice Problem Sets
Stereochemistry
Problem #1: Draw the cis and trans stereoisomers of the following compounds.
a) 1 – ethyl – 3 – methylcyclobutane
b) 2 – methyl – 3 – heptene
c) 1 – fluoro – 4 – iodo – cyclohexane
d) 1,3 – dichlorocyclobutane
Problem #2: Tetracycline is a broad - spectrum antibiotic used to treat such diseases as
Chlamydia, gonorrhea, and acne. Answer the following questions on this antibacterial
using the structure shown below.
N
OH
H3C
H
OH
NH2
OH
OH
O
OH
O
O
a) Indicate the hybridization of all carbons.
b) Designate all asymmetric carbons with an asterisk.
c) Assign a configuration of R or S to each chiral carbon.
Problem #3: Provide the correct systematic name (IUPAC name) of the following
compounds, including the proper R or S designation.
CH(CH 3)2
a) H3C
C
CH 2Br
CH 2CH 3
b) CH 3CH 2
C
CH 2Cl
CH 2CHCl
c)
NH2
CH=CH 2
OH
d) H
OH
e) Br
CH2CH3
CH2I
f) H
CH 2C(CH 3)3
H
CH2OH
OCH2CH3
N(CH3)2
Problem #4: Which of the following cyclic compounds are chiral? Explain.
Cl
Cl
a)
Cl
b)
Cl
Cl
c)
Cl
d)
Cl
1
Cl
Cl
e)
CH 2Cl
Problem #5: Determine whether each of the following pairs are enantiomers,
diasteriomers, constitutional isomers, or the same compound.
CH 2CH 3
CH 3
H CH3 H3C H
H
OH HO
H
H Br H H
a)
and
H
b)
Br Br
Br
and
H3C
H
c)
H
H
CH3
and
Br
H
CH 2CH 3
and H
CH 2CH 3
Br
Br
OH
e)
CH2CH3
and
HO
CH3
Br
CH 3
OH
d) H3C
H
HO
Cl
Problem #6: Provide the product(s) obtained when the following reagents are reacted
with cis–2–butene and trans–2–butene. If the products exist as specific stereoisomers,
show which isomers are formed.
a) H2O, H2SO4
b) Br2, CH2Cl2
c) Br2, H2O
d) 1) Hg(OAc)2, H2O
2) NaBH4
e) 1) BH3/THF
2) –OH, H2O2, H2O
f) H2SO4, CH3OH
g) HCl
h) peroxyacid
i) H2, Pd/C
Problem #7: Define and describe the following terms. Provide an example.
a) racemic mixture
b) enantiomers
c) diasteriomer
d) constitutional isomer
e) asymmetric carbon
f) meso compounds
g) syn addition
h) anti addition
Problem #8: The specific rotation of (R) – (+) – glyceraldehyde is +8.7o. Determine the
percent of (R) – glyceraldehdye in a mixture with the indicated specific rotations.
a) 0o
b) +1.4o
c) –8.7o
d) +8.0o
e) –3.4o
Problem #9: Carbon is not the only element that produces a chiral center. Determine the
R or S configuration for the compounds below. If it does not contain an asymmetric
element, explain why.
CH=CH 2
a)
H3C
N
+
H
O
Cl
-
b)
H3CO
CH 2CH 3
P
H
OCH 2CH 3
2
c)
..
NC
N
H
CH 2CH 3
Cl