2010 Chapter 8 homework SOLUTIONS _v2 - Department of ...

ILLINOIS STATE UNIVERSITY
DEPARTMENT OF CHEMISTRY, ILLINOIS STATE UNIVERSITY, NORMAL, IL 61790-4160
Chapter 8: The Chemistry of the Alcohols
Read Section 8.1 (Nomenclature) and do exercises 8.1-8.2 on page 289 and
problems 24 and 25 and page 326.
1. Provide reasonable IUPAC names for the following molecules.
OH
2-Heptanol
OH
2,5,5-trimethyl-3-hexanol
Br
OH
6-bromo-1-heptanol
OH
cis-4-methyl-1-cyclohexanol
OH
F
7-Fluoro-5-isopropyl-4-octanol
7-Fluoro-5-(1-methylethyl)-4-octanol
OH
6-(1,1-Dimethylethyl)-3-methyl-2-nonanol
6-tert-Butyl-3-methyl-2-nonanol
© 2010, Prof. S. R. Hitchcock, Department of Chemistry, Illinois State University, Normal, IL 61790-4160 1

2. Provide acceptable IUPAC names for the following molecules.
A
OH
B OH
Br
A. 7-Bromo-4-(1-methylethyl)-2-octanol or 7-Bromo-4-isopropyl-2-octanol
B. trans-2-(1,1-dimethylethyl)cyclopentane or trans-2-tert-butylcyclopentane
3. Provide acceptable IUPAC names for the following molecules.
4. Draw a reasonable structure for the molecule (S)-3-methyl-3-heptanol.
OH
CH 3 CH 2 CH 2 CH 2
C CH 2 CH 3
CH 3
© 2010, Prof. S. R. Hitchcock, Department of Chemistry, Illinois State University, Normal, IL 61790-4160 2

Read Section 8.2 (Properties) and do problems 26 and 27 page 326.
5. The boiling point of methane is -161.7 o C and the boiling point of methanol is 65 o C. Provide a
strong defense for why there is greater than 200 o C difference in temperatures.
This involves the intermolecular forces that hold collections of these molecules together. The
bonds in methane are not polarized and so there is virtually no attraction between these
molecules. The OH group in methanol is strongly polarized positive at the hydrogen and
negative at the oxygen. This leads to extensive intermolecular bonding which gives rise to
the higher temperature requirement to break up this interaction.
6. Provide a strong rationale for why 1,2-ethanediol has a boiling point of 196-198 o C and butane has
a boiling point of -0.5 o C. Why are these two compounds so different
The molecular weights for these compounds are nearly the same. In the case of butane,
intermolecular London forces are responsible for the low boiling point. The instantaneous
dipole-dipole attraction is weak and not sufficient enough to give rise to a higher boiling
point. The compound 1,2-ethanediol has significant hydrogen bonding that serves to create
an intermolecular network of strong hydrogen bonding between molecules.
7. Consider the general structure for the α-amino acids: RCH(NH 2 )CO 2 H. Which of the side chains
below would enhance the hydrophilicity of an α-amino acid
(a) R = -CH 2 Ph
(b) R = -CH 2 OH
(c) R = -CH 2 (CH 2 ) 16 CH 3
(d) R = -CH(CH 3 ) 2
B
© 2010, Prof. S. R. Hitchcock, Department of Chemistry, Illinois State University, Normal, IL 61790-4160 3

Read Section 8.3 (Acid/Base chemistry) and do exercises 4-6 on pages 293-294 and
problems 30 and 31 on page 327.
8. Write out the dissociation expression for 1-butanol in water and the corresponding K a expression.
What is the average pK a for most alcohols
The average pK a is about 16 to 19.
CH 3 CH 2 CH 2 CH 2 OH + H 2 O CH 3 CH 2 CH 2 CH 2 O + H 3 O
CH 3 CH 2 CH 2 CH 2 O
H 3 O
K a =
CH 3 CH 2 CH 2 CH 2 OH
9. Which of the following acids has the greater acidity, CH 3 CH 2 OH or F 3 CCH 2 OH Provide a
strong rationale for your answer. It is not sufficient to suggest that one material has a lower pK a
than the other.
F 3 CCH 2 OH has the greater acidity due to the presence of the electronegative fluorines.
These fluorines stabilize the buildup of negative charge on the oxygen. A more stable
conjugate base leads to a more acidic compound. See page 292 in the text.
10. Which one of the following reagents would not be effective in terms of completely removing an
alcoholic proton (RO-H) from an alcohol such as butanol
(a) Na + - OH (sodium hydroxide)
(b) Na + - NH 2 (sodium amide)
A
(c) K + - H (potassium hydride)
(d) Li + - CH 2 CH 2 CH 2 CH 3 (n-butyllithium)
© 2010, Prof. S. R. Hitchcock, Department of Chemistry, Illinois State University, Normal, IL 61790-4160 4

Read Section 8.5 (Acid/Base chemistry) and do exercise 7 on pages 296 and
problem 34 on page 327.
11. Complete the following reactions. If there is no reaction, then write NR.
Br
KOH, dmf
S N 2
OH
Cl
OH
H
KOH, dmf
S N 2-E2 mix
H
H
I
Br
H 2 O
S N 1-E1
1. O S N 2
H 3 C O
Na
H
H
OH
O
O CH 3
H
H
OH
H
H
OH
2. NaOH
OMs
1.
O
O
Na
S N 2
O
O CH 3
OH
2. KOH
Cl
H 2 O
S N 1-E1
OH
Cl
NaOH, 0 o C
E2
12. Write in the reagent that would most effectively convert the following alkyl halides into their
corresponding alcohols. No stereochemistry is implied for these reactions.
© 2010, Prof. S. R. Hitchcock, Department of Chemistry, Illinois State University, Normal, IL 61790-4160 5

Read Section 8.6 (Acid/Base chemistry) and do exercises 8-11 on pages 300-304
and problems 38, 46, and 47 on page 328-329.
13. Complete the following reactions concerning the reduction of carbonyl compounds. If there is no
reaction, then write NR.
O
OH
H
NaBH 4 , CH 3 OH
H
H
O
OH
NaBH 4 , CH 3 OH
H
O
H
OH
1. LiAlH 4 , THF
2. dilute HCl
O
1. LiAlH 4 , THF
2. dilute HCl
OH
H
O
NaBH 4 , CH 3 OH
OH
H
O
1. LiAlH 4 , THF
2. dilute HCl
OH
H
O
1. LiAlH 4 , THF
2. dilute HCl
H
H
OH
14. Which of the reagents below would you use to accomplish the following transformation
(a)
(b)
(c)
(d)
O
HO
D
D = deuterium ( 2 H)
LiAlD 4 in ether followed by treatment with H 2 O
LiAlD 4 in ether followed by treatment with D 2 O
LiAlH 4 in ether followed by treatment with H 2 O
LiAlH 4 in ether followed by treatment with D 2 O
A
© 2010, Prof. S. R. Hitchcock, Department of Chemistry, Illinois State University, Normal, IL 61790-4160 6

Read Section 8.6 (Acid/Base chemistry) and do exercises 8-11 on pages 300-304
and problems 38, 46, and 47 on page 328-329.
15. Complete the following reactions concerning the reduction of carbonyl compounds.
CH 2 CHO
NaBH 4 , CH 3 OH
CH 2 CH 2 OH
O
H
OH
NaBH 4 , CH 3 OH
CH 3 O
O
CH 3 O
OH
1. LiAlH 4 , THF
2. dilute HCl
H
O
O
H
OH
OH
H
H CH 3
1. LiAlH 4 , THF
H CH 3
2. dilute HCl
CHO
1. LiAlH 4 , THF
CH 2 OH
2. dilute HCl
O
1. LiAlH 4 , THF
H
OH
2. dilute HCl
O
HO
H
NaBH 4 , CH 3 OH
© 2010, Prof. S. R. Hitchcock, Department of Chemistry, Illinois State University, Normal, IL 61790-4160 7

Read Section 8.6 (Acid/Base chemistry) and do exercises 8-11 on pages 300-304
and problems 38, 46, and 47 on page 328-329.
16. Complete the following reactions. It there is no reaction, then write NR and explain why there is
no reaction. If there is over-oxidation, then state so.
OH
K 2 CrO 7 , H 2 SO 4
O
CH 2 CH 2 OH
K 2 CrO 7 , H 2 SO 4
CH 2 CO 2 H
over-oxidation via the aldehyde
OH
CrO 3 , H 2 SO 4
No oxidation; teriary alcohols do not have the
necessary alpha proton
CH 2 CH 2 OH
CH 2
PCC
CH 2 Cl 2
OH K 2 CrO 7 , H 2 SO 4
CH 3
CH 2 CHO
CH 2
successful aldehyde
formation because of
there is no strong acid
present.
CH 3
O
OH
H 2 SO 4 , CrO 3
No oxidation; teriary alcohols do not have the
necessary alpha proton
17. Which of the following alcohols cannot be oxidized by a combination of chromium trioxide
(CrO 3 ) and sulfuric acid (H 2 SO 4 ) to a carbonyl compound
(a)
(b)
(c)
(d)
2-propanol
3-octanol
4-methyl-2-hexanol
3-ethyl-3-octanol
A
18. Using 2-methyl-2-pentanol, provide a strong rationale for why this alcohol does not react with
chromium trioxide and sulfuric acid. You must draw the chromate ester of this alcohol to
complete your answer.
CH 3 CH 2 CH 2
OH
O Cr O
CrO
C CH 3 , H 2 SO 4 O
3
CH 3 CH 2 CH 2 C CH 3
CH 3
CH 3
There is no hydrogen for removal during the oxidation process.
© 2010, Prof. S. R. Hitchcock, Department of Chemistry, Illinois State University, Normal, IL 61790-4160 8
O

Read Section 8.7 (organometallics chemistry) and do exercise 13 on pages 307-309
and problem 40 on page 328.
19. Complete the following reactions and identify the carbon atom that carries the negative charge.
Cl
2 Li metal, ether
Cl
+ LiCl
H 3 C
Br
OCH 3
Magnesium metal
ether
H 3 C
MgBr
OCH 3
Cl
2 Li metal, ether
Li
+ LiCl
CH 2 Cl
Magnesium metal
ether
CH 2 MgCl
Br
2 Li metal, ether
Li
+ LiBr
CH 2 F
Magnesium metal
ether
No reaction. The carbon-fluorine bond is
too strong.
CH 3
2 Li metal, ether
No reaction. There is no halogen
leaving group.
© 2010, Prof. S. R. Hitchcock, Department of Chemistry, Illinois State University, Normal, IL 61790-4160 9

20. Indicate the polarization of each of the BOLD bonds in the following molecules. The first
structure is completed for you.
δ
δ
H
H
δ
Cl
δ
Br
hydrogen chloride
hydrogen chloride
δ
δ
H O H
water
H
H
C
H
δ
O
H
δ
(methanol, CH 3 OH)
H 3 C
O
H
O
δ
δ
acetic acid, a carboxylic acid
sometimes written as CH 3 CO 2 H
O
H
O
δ
δ
benzoic acid, a carboxylic acid
21. The following reactions involve quenching organometallic reagents. These reactions are driven by
the formation of more stable compounds.
© 2010, Prof. S. R. Hitchcock, Department of Chemistry, Illinois State University, Normal, IL 61790-4160 10

Read Section 8.8 (organometallics chemistry) and do exercises 15 and 16 on page 309
and problems 43, 44, and 53 on pages 328-329.
22. Complete the following reactions. If there is no reaction, then write NR.
H
O
H
1.
2. dilute HCl
MgBr
OH
H
H
O
OH
H
1. CH 3 CH 2 MgBr
2. dilute HCl
H
CH 2 CH 3
O
1. CH 3 CH 2 OCH 2 Li
2. dilute HCl
HO CH 2 OCH 2 CH 3
O
1.
MgBr
HO
2. dilute HCl
O
1.
CH 2 CH 2 Li
HO
2. dilute HCl
CH 3
O
1.
MgCl
CH 2 CH 2
OH
CH 3
2. dilute HCl
23. What combination of reagents would NOT form the alcohol shown after a work up with dilute
HCl Circle the best choice.
© 2010, Prof. S. R. Hitchcock, Department of Chemistry, Illinois State University, Normal, IL 61790-4160 11

24. Complete the following reactions by writing in the products. If there is no reaction, then you
should write, NR.
Br
Mg o , ether
redox
MgBr
Cl
CH 2 OMe
Li o , ether
redox
Li
CH 2 OMe
+ LiCl
Br
O
H
1. CH 3 CH 2 MgBr
2. dilute HCl
Br
OH
H
CH 2 CH 3
O
1.
Li
ether
OH
2. dilute HCl
OCH 3
CH 3
1. Magnesium, ether
OCH 3
CH 3
2.
Br
CH 3 O
MgCl
H 3 C
CHO
O
OH
CH 3 O
HO
H
H
O
+
H 3 C
O
MgCl
© 2010, Prof. S. R. Hitchcock, Department of Chemistry, Illinois State University, Normal, IL 61790-4160 12

25. Complete the following. If there are multiple products, then you must clearly state which product
is the major product. Assume a work up for all reactions.
O
O
1. LiAlD 4 , ether
2. dilute HCl
NaBH 4 , CH 3 OH
OH
D
OH
H
CH 3
O
1. LiAlH 4 , ether
2. dilute HCl
CH 3
H
OH
O
OH
1. LiAlH 4 , ether
2. dilute HCl
CrO 3 , H 2 SO 4
OH
H
O
CH 3
OH
1.PCC, CH 2 Cl 2
CH 3
O
CH 3
OH
H
CH 3
2. Cyclopropyl lithium
H
CH 3
H
CH 3
O
H
OCH 3
1. NaBH 4 , EtOH
2. CD 3 MgBr
OH
H
H
OCH 3
O
H
H
OCH 3
MgBr
+ CD 3 H
Na 2 Cr 2 O 7 , H 2 SO 4
OH
OH
O
O
© 2010, Prof. S. R. Hitchcock, Department of Chemistry, Illinois State University, Normal, IL 61790-4160 13

26. Complete the following integrated reactions. Assume a work up for all reactions.
Br
1. Mg o , ether
2. CH 3 CH 2 CHO
MgBr
OH
C
O
CH 2 CH 3
3. Na 2 Cr 2 O 7 , H 2 SO 4
OCH 3
H CH 2 CH 3 C
OCH 3
OCH 3
(CH 3 ) 2 CH
OCH 3
OH
OH
C H
H
1.
N
H
CrO 3 Cl
(PCC)
2. CH 3 CH 2 MgCl
3. Na 2 Cr 2 O 7 , H 2 SO 4
4. CD 3 CD 2 MgBr, ether
(CH 3 ) 2 CH
(CH 3 ) 2 CH
O
C H (CH 3 ) 2 CH
OH
C H
CH 2 CH 3
O
C
CH 2 CH 3
OH
(CH 3 ) 2 CH
C
CD 2 CD 3
CH 2 CH 3
O
1. PCC, CH 2 Cl 2
2. CD 3 CH 2 CH 2 MgBr
3. dilute HCl
H
OH
CH 2 CH 2 CD 3
© 2010, Prof. S. R. Hitchcock, Department of Chemistry, Illinois State University, Normal, IL 61790-4160 14

27. Complete the following problems. If there is no reaction, then write NR.
O
OH
CH 2 CH 3
1.
CH 3 CH 2 MgBr, THF
2. dilute HCl
CH 2 CH 3
CH 2 CH 3
OH
O
CH 3
1.
CD 3 MgBr, THF
2. dilute HCl
CH 3
CD 3
O
CH 3
1.
MgBr
2. dilute HCl
OH
CH 3
HO CH 2 CH 2
O
1.
CH 2 CH 2 MgBr, THF
2. dilute HCl
O
1. CH 3 CH 2 CH 2 MgCl
HO
CH 2 CH 2 CH 3
2. dilute HCl
O
1. CH 3 CH 2 CH 2 MgCl
OH
H
CH 2 CH(CH 3 ) 2
2. dilute HCl
H
CH 2 CH(CH 3 ) 2
CH 2 CH 2 CH 3
© 2010, Prof. S. R. Hitchcock, Department of Chemistry, Illinois State University, Normal, IL 61790-4160 15

28. Complete the following integrated problems. Write out the products of each transformation.
OH
1. PCC, CH 2 Cl 2
2. CH 3 MgBr
O
OH
3. dilute HCl
CH 3
OH
1. PCC, CH 2 Cl 2
2. CH 3 CD 2 MgBr
3. dilute HCl
O
OH
CD 2 CH 3
1. Na 2 Cr 2 O 7 , H 2 SO 4
HO
CH 3
2.
MgBr
O
CH 3
HO
CH 3
3. dilute HCl
OH
1. PCC, CH 2 Cl 2
O
OH
2. (CH 3 )CHCH 2 Li
CH 2 CH(CH 3 ) 2
3. dilute HCl
OH
1. K 2 Cr 2 O 7 , H 2 SO 4
2. CH 3 MgBr
3. dilute HCl
No reaction. Tertiary alcohols cannot be
oxidized because they do not have the
hydrogen necessary for the elimination
process.
OH
1. CrO 3 , H 2 SO 4
2.
Li
O
OH
3. dilute HCl
© 2010, Prof. S. R. Hitchcock, Department of Chemistry, Illinois State University, Normal, IL 61790-4160 16

Read Section 8.9 (organometallics chemistry) and do exercises 19, 20, and 21 on pages
315-317 and problems 54-56 on pages 329-330.
29. Complete the following problem. Show all possible products.
1. PCC, CH 2 Cl 2
2. CD 3 MgBr, ether (D = deuterium, 2 H)
3. dilute HCl
methanol
4. PCC, CH 2 Cl 2
5. CT 3 Li, ether (T = tritium, 3 H)
6. dilute HCl
7. PCC, CH 2 Cl 2
8. CH 3 Na in ether
9. dilute HCl
H
OH
C H
H
O
OH
H C H H C H
CD 3
H
O
C
CD 3
H
OH
C CT 3
CD 3
O
C CT 3
CD 3
H 3 C
OH
C
CD 3
CT 3
Is this molecule chiral
© 2010, Prof. S. R. Hitchcock, Department of Chemistry, Illinois State University, Normal, IL 61790-4160 17

30. Design at least two different syntheses for the molecule that is illustrated below.
OH
C CH 3
CH 3
OH
OH
C CH 3
C CH 3
CH 3
CH 3
OH
C CH 3
MgBr
+
O
H 3 C CH 3
CH 3
O
C CH 3
+ CH 3 MgBr
© 2010, Prof. S. R. Hitchcock, Department of Chemistry, Illinois State University, Normal, IL 61790-4160 18

31. Design at least three different syntheses for the molecule that is illustrated below.
OH
CH 3 CH 2
C CH 3
OH
CH 3 CH 2
OH
C CH 3
CH 3 CH 2
C CH 3
A
C
B
CH 3 CH 2
OH
C CH 3
OH
CH 3 CH 2
C CH 3
OH
O
CH 3 CH 2
C CH 3
CH 3 CH 2
C
A
CH 3 MgBr
OH
MgBr
B
CH 3 CH 2
C CH 3
O
CH 3 CH 2
C CH 3
OH
O
C
CH 3 CH 2
C CH 3
CH 3 CH 2 MgBr
C CH 3
© 2010, Prof. S. R. Hitchcock, Department of Chemistry, Illinois State University, Normal, IL 61790-4160 19

32. Complete the following retrosynthesis problems by writing in the appropriate reagents. No more
than two steps are required for each of the following transformations.
Cl
Magnesium metal
ether solvent
MgCl
Br
OCH 3
lithium metal
ether solvent
Li
OCH 3
Br
1. Mg, ether
2. dilute HCl
H
CH 2 Cl
1. Li, ether
2. O
(Chapter 9)
CH 2 CH 2 CH 2 OH
O
CH 3
1. CH 3 CH 2 CH 2 MgBr
OHCH 3
2. dilute HCl
CH 2 CH 2 CH 3
© 2010, Prof. S. R. Hitchcock, Department of Chemistry, Illinois State University, Normal, IL 61790-4160 20