CHAPTER 22
ALCOHOLS, ETHERS, PHENOLS, AND THIOLS
SOLUTIONS TO REVIEW QUESTIONS
1.
The question allows great freedom of choice. These shown here are very simple examples
of each type.
(a) an alkyl
k halide
CH 3CH 2Cl
(b)
a phenol
(c)
an ether
( d)
an aldehyde
(e)
(f)
a ketone
a carboxylic acid
(g)
(h)
an ester
a thiol
OH
CH 3CH 2OCH 2CH 3
H
ƒ
CH 3C “ O
O
‘
CH 3CCH 3
CH 3COOH
O
‘
CH 3C ¬ OCH 2CH 3
CH 3CH 2SH
2.
Alkenes are almost never made from alcohols because the alcohols are almost always the
higher value material. This is because recovering alkenes from hydrocarbon sources in an
oil refinery
f
(primarily catalytic cracking) is a relatively cheap process.
3.
Oxidation of pri
r mar
ary alcohols yields aldehydes. Furt
rther oxidat
a ion yields car
arboxylic acids.
Examples:
O
‘
[O] "
CH 3CH 2OH
C H 3 C ¬ H + H 2O
O
O
‘
‘
[O] "
CH 3C ¬ OH
CH 3 C ¬ H
4.
1,2-Ethanediol is superior to methanol as an antifreeze because of its low volatility.
Methanol is much more volatile than water. If the radiator leaks gas under pressure
(normally steam), it would primarily leak methanol vapor so you would soon have no
antifreeze. Ethylene glycol has a lower volatility than water, so it does not present this
problem.
- 304 -
- Chapter 22 -
5.
Oxidation of alcohols affects
f
the hydroxyl carbon in two ways: (1) the carbon adds a new
bond to oxygen; (2) the carbon loses a bond to hydrogen. When the hydroxyl carbon is
not directly bonded to hydrogen (as in tertiary alcohols), oxidation is diff
fficult.
6.
Menthol affects
f
neurons that sense temperature. Binding of this alcohol to a neuron
adjusts the neuron’s temperature sensitivity. The neuron then signals “pleasantly cool”
even though the temperature is actually warm.
7.
The liver oxidizes ingested meth
t anol, fi
f rst to meth
t anal (fo
f rmaldehyde) and th
t en to meth
t anoic
acid (fo
f rmic acid). Meth
t anoic acid is much more toxic th
t an meth
t anol. This acid causes
metab
a olic acidosis and inhibition of centr
t al energ
r y metab
a olism th
t at can lead to death
t .
8.
The following classes of organic compounds can be easily formed from alcohols:
aldehydes, ketones, and carboxylic acids by oxidation; alkenes and ethers by dehydration;
esters by esterifi
f cation.
9.
±
benzene
O2
CH3CH “ CH2
H2SO4
propene
CH3
ƒ
¬ C¬ O ¬ O ¬ H
ƒ
CH3
dilute
H2SO4
cumene hydroperoxide
CH3
ƒ
¬ CH
ƒ
CH3
cumene
(isopropylbenzene)
OH
±
phenol
CH3CCH3
‘
O
acetone
10.
Some common phenols include (a) hydroquinone, a photographic reducer and developer,
f
vanillin, (d) thymol, used as an
(b) vanillin, a flavoring, (c) eugenol, used to make artificial
antiseptic in mouthwashes, (e) butylated hydroxytoluene (BHT) an antioxidant and,
(f) the cresols, used as disinfectants.
11.
Low molar mass ethers present two hazards. They are very volatile and their highly
flammable vapors form explosive mixtures with air. They also slowly react with oxygen in
the air to form unstable explosive peroxides.
12.
Ethanol (m olar
f nt
ar m ass
a = 46.07) is a liquid at room temperature because it has a significa
amount of hydrogen bonding between molecules in the liquid state, and thus has a much
higher boiling point than would be predicted from molar mass alone. Dimethyl ether
(m olar
ar m ass
a = 46.07) is not capable of hydrogen bonding to itself, so has low attraction
between molecules, making it a gas at room temperature.
- 305 -
- Chapter 22 -
SOLUTIONS TO EXERCISES
OH
1.
(a)
CH3
CH3
CH3CHCH3
(d)
CH3CHCH 2C CH3
OH
CH2 OH
( b)
CH
(e)
OH
OH
CH2 OH
CH3
(c)
CH3
CH3 CH2 CH CH2 CHCH2 OH
(f)
CH3CH2OH
OH
2.
(a)
OH
(d)
CH2 OH
OH
(b)
CH3 CCH2 CH3
(e)
CH3
CH3 C
CH
OH
CH2 OH
OH
CH3 OH
(c)
CH3 CHCH2 CH2 OH
CHCH2 CH2 CH3
(f)
CH3
CH3 C
CH3
CCH2 CH3
CH3 CH3
- 306 -
3.
There are only ffive isomers:
CH3
CH3CCH2 CH2OH
CH3
CH3
HO CH3
CH3
CH3 CHCCH3
CH3CH2CCH2 OH
CH3
CH
There are only eight isomers:
CH3
CH3
CH3
HO CH2CHCH 2CH2CH3 CH3CCH2 CH2 CH3
CH3
OH
CH3 CHCH2 CHCH3
CH3
CH3CH CH CH2CH3
OH
CH3CHCHCH2CH3
OH
OH
5.
OH
CH3C HCHCH2OH CH3 CHCCH3
CH3
4.
H3 C
CH3
CH3
CH3
CH3CH CH 2CH2CH2OH HOCH2CH2CHCH2CH3
CH3
CH3CH2 CCH2CH3
OH
(a) primary alcohols (where the hydroxyl carbon is bonded to one other carbon): c, f;
(b) secondary alcohols (where the hydroxyl carbon is bonded to two other carbons): a, e;
(c) tertiary alcohols (where the hydroxyl carbon is bonded to three other carbons): d; diol
(where the compound contains two hydroxyl groups): none; triols (where the compound
contains three hydroxyl groups): b.
- 307 -
- Chapter 22 -
6.
(a) primary alcohols (where the hydroxyl carbon is bonded to one other carbon): none;
(b) secondary alcohols (where the hydroxyl carbon is bonded to two other carbons):
a, c, d; (c) tertiary alcohols (where the hydroxyl carbon is bonded to three other carbons):
b, f; diol (where the compound contains two hydroxyl groups): none; triols (where the
compound contains three hydroxyl groups): e.
7.
The names of the compounds are:
(a) 1-butanol (butyl alcohol)
(b) 2-propanol (isopropyl alcohol)
(c) 2-methyl-3-phenyl-l-propanol
(d) oxirane (ethylene oxide)
(e)
(f)
(g)
2-methyl-2-butanol
2-methylcyclohexanol
2,3-dimethyl-1,4-butanediol
The names of the compounds are
(a) ethanol (ethyl alcohol)
(b) 2-phenylethanol
(c) 3-methyl-3-pentanol
(d) 1-methylcyclopentanol
(e)
(f)
(g)
3-pentanol
1,2-propanediol
4-ethyl-2-hexanol
8.
9.
10.
Chief product of dehydration
CH 3
ƒ
(a) CH 3C “ CHCH 3
(b) CH 3CH “ CHCH 2CH 3
2-methyl-2-butene
2-pentene
(c)
cyclohexene
Chief product of dehydration
CH3
(a)
1-methylcyclopentene
(b)
(c)
CH 3CH “ CHCH 3
CH 3
ƒ
CH 3C “ CHCH 2CH 3
2-butene
2-methyl-2-pentene
- 308 -
- Chapter 22 -
OH
11.
(a)
(c)
OH
CH3
cyclopentanol
(b)
CH3
CH2
1-methylcyclohexanol
CH2OH
CH
CH3
2-methyl-1-butanol
OH
CH3
12.
OH
(a)
(c)
CH3
CH3 CH2CHCH2 CH3
3-pentanol
1,2-dimethylcyclohexanol
CH 3
(b)
HOCH2CH 2CH 2
C
CH 3
CH 3
4,4-dimethy1-1pentanol
13.
Primary alcohols oxidize to carboxylic acids; secondary alcohols oxidize to ketones;
tertiary alcohols don’t easily oxidize.
O
(a)
CH3CCH2CH3
( b)
HOOCCH2CHCH2CH3
butanone
3-ethylpentanoic acid
CH2CH3
- 309 -
- Chapter 22 -
O
14.
(c)
CH3CCH3
( d)
NR
acetone, propanone
Primary alcohols oxidize to carboxylic acids; secondary alcohols oxidize to ketones;
tertiary alcohols don’t easily oxidize.
(a) HCOOH, methanoic acid, formic acid.
(b) NR
(c) CH3COOH, ethanoic acid, acetic acid
O
(d)
15.
CH 3 CH 2 CCH 2 CH 2 CH 3
3-hexanone
k group and oxygen bonded to
Upon ester hydrolysis, the alcohol forms from the alkyl
the C=O.
(a)
HOCH2CH2CH2CH3
(b)
HOCH2CH3
1-butanol
ethanol
OH
(c)
16.
2-propanol
CH3 CHCH3
Upon ester hydrolysis, the alcohol forms from the alkyl
k group and oxygen bonded to
the C=O.
OH
(a)
cyclopentanol
CH 3
17.
( b)
HO CH 2 CH CH 3 2-methyl-1-propanol
(c)
CH3OH
(a)
CH3CHBr CH3
(b)
Br
methanol
2-bromopropane
bromocyclohexane (cyclohexyl bromide)
- 310 -
- Chapter 22 -
(c)
18.
(a)
( b)
(c)
19.
CH 3
ƒ
CH 3CHCH 2CH 2Br
1-bromo-3-methylbutane
CH 3CHCH 2CH 3
ƒ
OH
CH 2CH 3
ƒ
CH 3CHCHCH 2CH 3
ƒ
OH
2-butanol
3-ethyl-2-pentanol
¬ OH
cyclopentanol
140°C "
(a)
O4
2 CH 3CH 2OH + H 2SO
CH 3CH 2OCH 2CH 3 + H 2O
diethyl ether
(b)
CH 3CH 2CH 2OH + H 2SO
O4
(c)
O
‘
K2Cr2O7
CH 3CH(OH)CH 2CH 3 99
:
H
C
C
3 CH 2CH 3 + H 2O
H SO
O
180°C "
2
CH 3CH “ CH 2 + H 2O
propene
4
2-butanone
( d)
O
‘
H+
CH 3CH 2C ¬ OCH 2CH 3 99:
CH CH 2COOH + CH 3CH 2OH
H O
2
3
propanoic acid
20.
(a)
2 CH 3CH 2OH + 2 Na ¡ 2 CH 3CH 2O -N a+ + H 2
(b)
O
‘
K2Cr2O7
CH 3CH 2CH 2CH 2OH 99
:
H
H
C
C
C
H
C
3
2
2 OH
H SO
O
2
(c)
(d)
¬ CH “ CH2
ethanol
4
H 2O
¬ CHCH3
ƒ
OH
H2SO4
O
O
‘
‘
CH 3CH 2C ¬ OCH 3 + NaO
a H ¡ CH 3CH 2C ¬ O -Naa+ + CH 3OH
- 311 -
- Chapter 22 -
21.
(a)
(b)
(c)
2-methyl-l-propanol
OH
ƒ
CH 2 ¬ CH ¬ CH 3
ƒ
CH 3
3-methyl-2-butanol
OH
ƒ
CH 3 ¬ CH ¬ CH ¬ CH 3
ƒ
CH 3
cyclopentanol
¬ OH
22.
(a)
(b)
(c)
Methanol, CH 3 ¬ OH
CH 3
ƒ
2,2-dimethyl-l-propanol CH 3 ¬ C ¬ CH 2 ¬ OH
ƒ
CH 3
CH 3
ƒ
3,3-dimethyl-1-pentanol CH 3 ¬ CH 2 ¬ C ¬ CH 2CH 2 ¬ OH
ƒ
CH 3
23.
(a)
(b)
(c)
methanol
2-methyl- l-propanol
cyclohexanol
24.
(a)
(b)
(c)
cyclopentanol
2-propanol
2-methyl-2-propanol
25.
(a)
o-methylphenol
(b)
m-dihydroxybenzene
OH
OH
CH3
OH
- 312 -
- Chapter 22 -
(c)
4-hydroxy-3-methoxybenzaldehyde
H¬C“O
OCH3
OH
26.
(a)
p-nitrophenol
(b)
2,6-dimethylphenol
OH
OH
H3C
CH3
NO2
(c)
o-dihydroxybenzene
OH
OH
27.
(a)
(b)
phenol
m-methylphenol
(c)
(d)
28.
(a)
(b)
p-dihydroxybenzene (hydroquinone) (c)
2,4-dimethylphenol
(d)
29.
Order of increasing solubility in water [c (lowest), a, b, d (highest)]
(c) CH 3CH 2CH 2CH 2CH 3 (1)
(b) CH 3CH(OH)CH 2CH 2CH 3 (3)
(a) CH 3CH 2OCH 2CH 2CH 3 (2)
(d) CH 3CH(OH)CH(OH)CH 2CH 3 (4)
30.
Order of decreasing solubility in water: [a (highest), d, c, b (lowest)]
(a) CH 3CH(OH)CH(OH)CH 2OH (1)
(c) CH 3CH 2CH 2CH 2OH (3)
(d) CH 3CH(OH)CH 2CH 2OH (2)
(b) CH 3CH 2OCH 2CH 3 (4)
31.
The three compounds have about the same molar mass but differ
f with respect to hydrogen
bonding and polarity. Compound (b) (1-propanethiol) does not hydrogen bond, is
nonpolar, and so, has the lowest boiling point. Compound (c) (diethyl ether) is polar but
does not hydrogen bond to itself. It has a higher boiling point than compound (b).
Compound a (1,2-propanediol) hydrogen bonds to itself and has the highest boiling point.
- 313 -
2-ethyl-5-nitrophenol
4-bromo-2-chlorophenol
2,4-dinitrophenol
m-hexylphenol
- Chapter 22 -
32.
The three compounds hav
a e about the same molar mass but differ
f with respect to hydrogen
bonding and polarity. Compound (c) (pentane) does not hydrogen bond, is nonpolar, and
so, has the lowest boiling point. Compound (b) (diethyl ether) is polar but does not
hydrogen bond to itself. It has a higher boiling point than Compound (c). Compound (a)
(2-butanol) hydrogen bonds to itself and has the highest boiling point.
33.
(a)
( b)
(c)
common, isopropyl methyl ether; IUPA
P C, 2-methoxypropane
common, ethyl phenyl ether; IUPA
P C, ethoxybenzene
common, butyl ethyl ether; IUPA
P C, 1-ethoxybutane
34.
(a)
(b)
(c)
common, ethyl methyl ether; IUPA
P C, methoxyethane
common, ethyl isobutyl ether; IUPA
P C, 1-ethoxy-2-methylpropane
common, ethyl phenyl ether; IUPA
P C, ethoxybenzene
35.
Fourteen isomeric ethers; C6H 14O
CH 3OCH 2CH 2CH 2CH 2CH 3
methyl-n-pentyl ether (1-methoxypentane)
CH 3
ƒ
CH 3OCHCH 2CH 2CH 3
2-methoxypentane
CH 2CH 3
ƒ
CH 3OCHCH 2CH 3
3-methoxypentane
CH 3
ƒ
CH 3OCH 2CHCH 2CH 3
1-methoxy-2-methylbutane
CH 3
ƒ
CH 3OCH 2CH 2CHCH 3
1-methoxy-3-methylbutane
CH 3 CH 3
ƒ
ƒ
CH 3OCH ¬ CHCH 3
2-methoxy-3-methylbutane
CH 3
ƒ
CH 3OCH 2C ¬ CH 3
ƒ
CH 3
1-methoxy-2,2-dimethylpropane
CH 3CH 2OCH 2CH 2CH 2CH 3
n-butyl ethyl ether (1-ethoxybutane)
CH 3
ƒ
CH 3CH 2OCHCH 2CH 3
sec-butyl ethyl ether
(2-ethoxybutane)
CH 3
ƒ
CH 3CH 2OCH 2CHCH 3
ethyl isobutyl ether
(1-ethoxy-2-methylpropane)
- 314 -
- Chapter 22 -
35.
36.
(cont).
CH 3
ƒ
CH 3CH 2OC ¬ CH 3
ƒ
CH 3
t-butyl ethyl ether
(2-ethoxy-2-methylpropane)
CH 3CH 2CH 2OCH 2CH 2CH 3
di-n-propyl ether
(1-propoxypropane)
CH 3
ƒ
CH 3CH 2CH 2OCHCH 3
isopropyl-n-propyl ether
CH 3 CH 3
ƒ
ƒ
CH 3CHOCHCH 3
diisopropyl ether
Six isomeric ethers: C5H 12O
CH 3
ƒ
CH 3OCHCH 2CH 3
sec-butyl methyl ether
(2-methoxybutane)
CH 3OCH 2CH 2CH 2CH 3
n-butyl methyl ether
(1-methoxybutane)
CH 3
ƒ
CH 3OCCH 3
ƒ
CH 3
t-butyl methyl ether
(2-methoxy-2-methylpropane)
CH 3
ƒ
CH 3OCH 2CHCH 3
isobutyl methyl ether
(1-methoxy-2-methylpropane)
CH 3
ƒ
CH 2CH 2OCHCH 3
ethyl isopropyl ether
(2-ethoxypropane)
CH 3CH 2OCH 2CH 2CH 3
ethyl n-propyl ether
(1-ethoxypropane)
37.
Possible combinations of reactants to make the following ethers by the Williamson
W
synthesis:
CH 3ONa + CH 3CH 2Cl or
(a) CH 3CH 2OCH 3
CH 3CH 2ONa + CH 3Cl
- 315 -
- Chapter 22 -
(b)
CH2OCH2CH3
CH2ONa
CH2Cl
or
(c)
38.
O ¬ CH2CH3
±
CH3CH2Cl
±
CH3CH2ONa
ONa
±
CH3CH2Cl
Possible combinations of reactants to make the following ethers by the Williamson
W
synthesis:
CH 3CH 2CH 2ON a + CH 3CH 2CH 2Cl
(a) CH 3CH 2CH 2OCH 2CH 2CH 3
CH 3
CH 3
ƒ
ƒ
HCONa + CH 3CH 2CH 2Cl
(b) HCOCH 2CH 2CH 3
ƒ
ƒ
CH 3
CH 3
(c)
O
cannot be made by the W
Williamson synthesis. Cannot use
secondary RX.
39.
IUPA
P C names
(a) 2-methyl-2-butanethiol
(b) cyclohexanethiol
(c) 2-methyl-2-propanethiol
(d) 2-methyl-3-pentanethiol
40.
IUPA
P C names
(a) 2-methylcyclopentanethiol
(b) 2,3-dimethyl-2-pentanethiol
(c) 2-propanethiol
(d) 3-ethyl-2,2,4-trimethyl-3-pentanethiol
41.
(a)
(b)
3CHCH 3
ƒ
SH
CH3CH2 CHCH2CH2CH2SH
CH
CH3 CH3
- 316 -
(c)
SH
CH3
42.
(a)
SH
CH2CH3
43.
( b)
CH 3CH 2CHCH 2CH 3
ƒ
SH
(c)
CH 3
ƒ
CH 3CH 2CCH 2SH
ƒ
CH 3
OH
4-hexylresorcinol or 4-hexyl-1,3-dihydroxybenzene
OH
CH2(CH2)4CH3
44.
OH
OH OH
cis-1,2-cyclopentanediol
45.
OH
trans-1,2-cyclopentanediol
The phenol compound (3-methylphenol) is more acidic than the alcohol compound
(benzyl alcohol) but is less acidic than carbonic acid.
- 317 -
- Chapter 22 -
46.
The name “catecholamine” is built of two pieces, “catechol” and “amine.” A catechol is a
phenol derivative that contains an additional hydroxyl group (o-hydroxyphenol).
OH
OH
(An amine is a “–NH2” functional group.)
47.
Oxidation products from ethylene glycol include
O
HOCH2
CH
O
HC
O
CH
HOCH2 COOH
HOOCCOOH
O
HC
48.
COOH
a e the most positive oxidation number
In each compound, the most oxidized carbon will hav
and, commonly, the most bonds to oxygen. In contrast, the most reduced carbon will hav
a e
the most negative oxidation number and, commonly, the most bonds to hydrogen. The most
reduced carbon has been circled while an asterisk has been placed by the most oxidized
carbon.
oxidation number = –1,
two bonds to hydrogen
oxidation number = +1,
two bonds to oxygen
CH2OH OH
O
*
HC
CH
CH CH
oxidation number = –3,
three bonds to hydrogen
oxidation number = –3,
three bonds to hydrogen
oxidation number = +3,
three bonds to oxygen
O
CH3(CH2)16
*C
OH
oxidation
number = +3,
three bonds to
oxygen
O
O
CH3 C
*C
OH
OH OH
ribose
(a sugar)
palmitic acid
(a fat)
-
pyruvic acid
(a metabolite)
- Chapter 22 -
49.
(a)
OH
O
2ƒ
‘
Cr2O7
CH 3CHCH 3 999
CH
CC
H3
:
3
H+
H+
(b)
CH 3CH 2CH 2CH “ CH 2 99: CH 3CH 2CH 2CHCH 3
H2O
ƒ
OH
(c)
2 CH 3CH 2OH + 2 Naa (m etal)
a ¡ 2 CH 3CH 2ON a + H 2
(d)
(e)
Cr2O7
CH 3CH 2CH “ CH 2 99: CH 3CH 2CHCH 3 999
: CH 3CH 2CCH 3
H+
H2O
ƒ
‘
OH
O
H2SO
O4
CH 3CH 2CH 2CH 2OH 99: CH 3CH “ CHCH 3 + CH 3CH 2CH “ CH 2
¢
HCl "
(f)
2-
H+
CH 3CH 2CHCH 3
ƒ
Cl
CH 3CH 2CH 2Cl
NaO
a H"
CH 3CH 2CH 2OH 999
:
H+
O– Na±
OH
± NaOH ¡
50.
2Cr2O7
± H2O
CH3
CH3
CH 3CH 3 + Cl 2
light "
CH 3CH 2Cl + HCl
O– Na±
OCH2CH3
± CH3CH2Cl ¡
CH3
± NaCl
CH3
- 319 -
O
‘
CH
C
3
2 ¬H
- Chapter 22 -
51.
A simple chemical test to distinguish between:
(a) ethanol and dimethyl ether. Ethanol will react readily with potassium dichromate
and sulfuric acid to make acetaldehyde. Visibly
V
, the orange color of the dichromate
changes to green. Ethanol reacts with metallic sodium to produce hydrogen gas.
Dimethyl ether does not react with either of these reagents.
(b) 1-pentanol and 1-pentene. 1-pentene will rapidly decolorize bromine as it adds to
the double bond. 1-pentanol does not react.
(c) p-methylphenol has acidic properties so it will react with sodium hydroxide.
Methoxybenzene does not hav
a e acidic properties and will not react with sodium
hydroxide.
52.
Isomers of C8H 10O
¬ CH2CH2OH
¬ CHCH3
ƒ
OH
CH2OH
OH
CH2OH
CH3
CH2CH3
¬ OCH2CH3
CH2OH
CH2CH3
H3C
CH3
OH
¬ CH2OCH3
OCH3
CH3
H3C
HO
CH3
53.
Only compound (a) will react with NaOH.
O – Na±
OH
CH2CH3
OCH3
OCH3
± NaOH ¡
± H2O
- 320 -
- Chapter 22 -
54.
Order of increasing boiling points.
6
1-pentanol
1-octanol 6 1,2-pentanediol
138°C
194°C
210°C
All three compounds are alcohols. 1-pentanol has the lowest molar mass and hence the
lowest boiling point. 1-octanol has a higher molar mass and therefore a higher boiling
point than 1-pentanol. 1,2-pentanediol has two ¬ OH groups and therefore forms more
hydrogen bonds than the other two alcohols which causes its higher boiling point.
55.
(a)
The primary carbocation that is formed ffirst is unstable.
CH 3
ƒ
+ CH ¬ CH ¬ CH ¬ CH
2
2
3
Thus, the primary carbocation shifts to a much more stable, tertiary carbocation
C H3
ƒ
CH 3 ¬ C ¬ CH 2 ¬ CH 3
+
It is this intermediate that goes on to form the major product, 2-methyl-2-butene.
(b)
CH 3
ƒ
CH 3 ¬ C “ CH ¬ CH 3
Hydration will not form 2-methyl- l-butanol because the double bond lies between
the middle two carbons in 2-methyl-2-butene. By Markovnikov’s Rule, the ¬ H
will add to the double bonded carbon that already has a hydrogen. Thus, 2-methyl2-butanol will be the major product.
- 321 -