CHAPTER 10: ANSWERS TO SELECTED PROBLEMS
SAMPLE PROBLEMS (“Try it yourself”)
O
10.1 CH3 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH CH CH2 CH2 CH2 CH2 CH2 CH2 CH2 C OH
CH3
10.2
CH3
CH
CH2 CH2 CH2 CH3
This compound is called 2-methylhexane.
O
10.3
CH2 CH
10.4
a) This is a secondary alcohol.
C
CH3
b) This is a primary alcohol.
OH
10.5
10.6
CH
CH3
heptanal
O
10.7
CH3 CH2 CH2 CH2 CH2 CH2 CH2
10.8
2-hexanone
C
H
10.9 Cyclohexane has the lowest boiling point, followed by cyclohexanone, followed by
cyclohexanol.
10.10 Nonanal has the lowest solubility in water, followed by heptanal, followed by pentanal.
10.11
CH2
S
S
CH2
CH3
10.12 You make two molecules of CH3
CH2 CH
SH
10.13 This is a reduction. The product contains two additional hydrogen atoms that were not in
the reactant. (One of them is bonded to the nitrogen atom, and the other is bonded to ring carbon
to the left of the nitrogen.)
O
10.14
C
OH
10.15 a) Adipic acid has the highest boiling point.
b) Adipic acid has the highest solubility in water.
10.16
HO
O
OH
O
C
CH
CH2 C
OH
+ NAD+
HO
O
O
C
C
O
CH2
C OH
+ NADH + H+
10.17 This reaction is a dehydrogenation, and involves the conversion of an alkane-like region
of the reactant into an alkene group. In this type of reaction, the coenzyme is FAD.
SECTION PROBLEMS
Section 10.1
O
10.1
CH3 CH CH
10.2
a) CH3 CH2 CH2 CH2 CH3
C
CH3
b)
…which we would normally write as:
H
10.3
rest of molecule
CH3
H
a) This is an oxidation.
b) This is a reduction.
(When you convert a single bond into a double bond, you must remove hydrogen atoms,
so each carbon atom still makes four bonds. Therefore, converting a single bond into a double
bond is an oxidation. By the same reasoning, converting a double bond into a single bond is a
reduction. When the reactant is a cyclic compound, you may not see the hydrogen atoms written
out, but you should be aware that they are there.)
Section 10.2
O
10.4
a) CH3
O
CH2 C
b) CH3
H
C
CH
CH3
CH3
c) This compound cannot be oxidized.
10.5
a) primary alcohol
c) tertiary alcohol
O
b) secondary alcohol
d) secondary alcohol
OH
10.6
d)
OH
a) CH3 CH
CH2 CH2 CH3
CH3
b) CH3 CH
CH2 CH
CH3
OH
c)
O
10.7
CH3
d)
OH
O
CH2
C
CH
C
rest of molecule
Section 10.3
10.8
a) 2-hexanone
b) propanal
10.9
a) acetaldehyde
b) acetone
c) pentanal
d) cyclopentanone
O
10.10 a) CH3 CH2
C
O
CH2
CH3
b) CH3 CH2 CH2 CH2 CH2 CH2 CH2
O
O
c) H
C
H
d)
10.11 Pentane boils at 36ºC, butanal boils at 75ºC, and 1-butanol boils at 99ºC.
C
H
10.12 The solubility of pentane is 0.1 g/L, the solubility of pentanal is 12 g/L, and the solubility
of heptanal is 1.2 g/L.
Section 10.4
10.13
CH3
CH2 CH2 CH
S
S
CH
CH3
CH2 CH2 CH3
CH3
10.14 You make two molecules of CH3 CH2
SH
10.15 This reaction is an oxidation. Ascorbic acid loses two hydrogen atoms during this
reaction.
C
C
HO
C
OH
C
O
O
Section 10.5
CH3
10.16 a) CH3
CH
O
CH2 C
O
b)
OH
10.17 a) propanoic acid
C
b) heptanoic acid
O
O
10.18 a) H
OH
C
b) CH3
OH
CH2 CH2 CH2 C
OH
10.19 The solubility of pimelic acid is 25 g/L, and the solubility of heptanoic acid is 2.4 g/L.
Section 10.6
10.20 NADPH
10.21 a) The coenzyme is NAD+.
b)
OH
O
CH2
C
OH
+
NAD+
H
O
O
C
C
OH
+
NADH + H+
10.22 The second hydrogen atom loses its electron and becomes H+, which is released into the
surrounding solution (and is promptly neutralized by the buffers in the solution).
Section 10.7
10.23 A metabolic pathway is a sequence of reactions that convert one important molecule into
another in a living organism.
10.24 The first reaction is a dehydrogenation:
O
HO
C
O
CH2 CH2
O
C
OH
HO
O
C
CH
O
OH
C
CH
C
CH
OH
The second reaction is a hydration:
O
HO
C
O
CH
CH
C
HO
OH
O
CH2
C
OH
The third reaction is an oxidation. This reaction produces the final product, oxaloacetic acid.
HO
O
OH
C
CH
O
CH2
C
OH
HO
O
O
C
C
O
CH2
C
OH
CUMULATIVE PROBLEMS (Odd-numbered problems only)
10.25 a) 4-octanone
b) butanoic acid
10.27 a) formaldehyde
b) acetone
c) hexanal
d) cycloheptanone
O
O
10.29 a) CH3
C
CH2 CH2 CH2
CH3
b) CH3 CH2 CH2 CH2
C
OH
d)
O
10.31 a) CH3 CH2
C
H
O
O
c) CH3 CH2
C
O
CH2 CH3
b) CH3
C
OH
O
c) H
C
CH2 CH2 CH3
d) CH3 CH2
S
S
CH2 CH3
O
O
e)
f)
CH2
C
OH
g) This compound cannot be oxidized, because it is a tertiary alcohol.
h) This compound also cannot be oxidized. (Ketones cannot be oxidized.)
OH
10.33 a) CH3
CH2 CH2 CH2 CH2
OH
b) CH3
CH
CH3
OH
c) CH2
d)
e) Two molecules of CH3
OH
SH
CH3
10.35 a) CH3 CH2 CH2 CH2 CH3
O
10.37
HO
C
b) CH3
CH2 CH
CH3
O
CH2 CH
CH
C
rest of molecule
10.39 a) These molecules are isomers. Both of them have the molecular formula C5H10O.
b) These molecules are isomers. Both of them have the molecular formula C5H10O.
c) These molecules are not isomers, because they have different molecular formulas. 2pentanone is C5H10O, while 2-pentanol is C5H12O.
d) These molecules are isomers. Both of them have the molecular formula C5H10O.
10.41 The student is incorrect, because 4-pentanone is simply an incorrect name for 2pentanone. In other words, “2-pentanone” and “4-pentanone” are actually the same molecule.
There are really only two ketones that have a five-carbon unbranched chain.
10.43 a) propanal (it has a polar functional group, while propane does not)
b) 2-butanol (it can form hydrogen bonds, while 2-butanone cannot)
c) pentanoic acid (both molecules are acids, but pentanoic acid is a larger molecule)
10.45 a) 2-butanone (both molecules are ketones, but 2-butanone has the shorter hydrocarbon
chain)
b) pentanal (it contains a functional group that can accept hydrogen bonds from water)
c) the second molecule (it contains two hydrogen-bonding functional groups)
O
10.47
HO
C
OH
CH
CH2
CH2
NH2
10.49
O
aldehyde
OH
OH
OH
OH
O
carboxylic acid
H
C
CH
CH
CH
CH
C
OH
four alcohol groups
b) The aldehyde group and the four alcohol groups can be oxidized.
c) The aldehyde group can be reduced.
O
O
10.51 Compound A is CH3 CH2 CH2
C
H and compound B is CH3 CH2 CH2
OH
10.53 Compound E is
CH
CH2 CH3
Compound F is
CH
CH
Compound G is
CH2 CH2 CH3
10.55 a) oxidation
b) reduction
O
10.57 a) CH3 C
CH2
O
c) CH3
C
CH2
O
O
C
C
O
O
C
C
CH3
c) oxidation
O
H
OH
b) CH3
C
CH2
CH3
O
CH
C
OH
C
OH
10.59 a) FAD (This is a dehydrogenation)
b) NADPH (This is a reduction)
c) NAD+ (This is an oxidation that does not involve an alkane → alkene conversion)
10.61 This conversion is an oxidation, so the coenzyme is NAD+.
O
O
H and butanoic acid is CH3 CH2 CH2 C
10.63 a) butanal is CH3 CH2 CH2 C
OH
b) The molecular formula of butanal is C4H8O, and the molecular formula of butanoic
acid is C4H8O2.
c) 2 C4H8O + O2 → 2 C4H8O2
d) You will form 12.2 g of butanoic acid (the calculator answer is 12.21901598 g). This
type of problem is covered in Section 6.3.
10.65 You need 2.3 g of acetic acid (the calculator answer is 2.25195 g). The molecular
formula of acetic acid is C2H4O2, and the formula weight is 60.052. To make 75 mL (0.075 L)
of 0.50 M acetic acid, you need 0.0375 moles of acetic acid, which weighs 2.25195 grams.
10.67 a) The carbon atom is positively charged and the oxygen atom is negatively charged.
b) The electronegativity of carbon is 2.5, and the electronegativity of oxygen is 3.5. The
atom with the higher electronegativity has the stronger attraction for electrons, so the oxygen
pulls the bonding electrons toward itself and away from the carbon. As a result, the oxygen is
slightly negatively charged, and the carbon is slightly positively charged.
10.69 a) primary
b) secondary
c) tertiary
10.71 The structures labeled a and b can be oxidized. Tertiary alcohols cannot be oxidized,
because they do not have a hydrogen on the carbon that is adjacent to the OH group.
10.73 Dehydrogenation reactions are much more difficult in general than other oxidations. In
this case, the alcohol group is easier to oxidize than the alkane portion of the molecule, so the
product will be an aldehyde, acetaldehyde.
O
CH3
C
H
10.75 The first reaction is a dehydrogenation.
O
CH3 CH2 CH2
C
O
rest of molecule
CH3 CH
CH
C
rest of molecule
The second reaction is a hydration. Note that the alcohol group ends up on the second carbon
from the left.
O
CH3 CH
CH
C
OH
rest of molecule
CH3 CH
O
CH2
C
rest of molecule
The third reaction is an oxidation.
OH
CH3 CH
O
CH2
C
O
rest of molecule
CH3
C
O
CH2
C
rest of molecule
10.77 The first reaction and the third reaction require a redox coenzyme. The first reaction uses
FAD, and the third reaction uses NAD+.