Unit 2, Lessons 08 and 09: Answers to Homework on Substituted Hydrocarbons
Page 28, Q 18 – 21 (alkyl halides)
Page 26-27, Q 14 – 17 (alcohols)
Lesson 08
Page 36, Q 30 – 33 (aldehydes and ketones)
Page 40, Q 34 – 37 (carboxylic acids)
Lesson 09
Page 32, Q 26a,c, 27a,b, 29 (amines)
Page 28 Answers to Homework on Alkyl Halides:
18. Bromoethane:
condensed structural formula: CH3 – CH2 – Br
I
b) 2,3,4-triiodo-3-methylheptane
I
I
CH3
CH3
or: CH3 – CH – C – CH – CH2 – CH2 – CH3
I
I
I
F
19. The molecule is 1,2-difluorocyclohexane.
I
F
20.
CH3 – CH – CH3
2-iodopropane
I
21.
CH2 – CH2 – CH3
1-iodopropane
Page 26-27 Answers to Homework on Alcohols
14. a)
b)
c)
d)
e)
1-propanol, a primary alcohol
2-butanol, a secondary alcohol
cyclobutanol, a secondary alcohol
2,3-pentanediol, a secondary alcohol
2,4-dimethyl-1-heptanol, a primary alcohol
15a) methanol
b) 2-propanol
OH
CH3
c) 2,2-butanediol
OH
OH
CH3
CH
CH3
CH3
C
OH
CH2
CH3
Page 26-27 Answers to Homework on Alcohols
15d) 3-ethyl-4-methyl-1-octanol
CH2
CH2
HO
OH
CH3
CH
CH2
15e) 2,4-dimethyl-1-cyclopentanol
CH
CH2
CH2
CH2
CH3
CH3
CH3
CH3
16a) the molecule should be named 1,3-pentanediol
b) 3,4-diethyl-1-decanol
c) 3-methyl-2-pentanol (look for the longest carbon chain)
17.
H
H
C
methanol is tetrahedral shaped
around the carbon atom, but
bent around the oxygen atom
O
H
H
Page 36 Answers to Homework on Aldehydes and Ketones
30a)
b)
c)
d)
e)
butanal
3-octanone
2-methyl-3-hexanone
2-ethyl butanal
4-ethyl-3-methyl-2-heptanone
31a) 2-propyl pentanal
CH2
O
b) cyclohexanone
CH2
CH3
O
C
CH
CH2
CH2
CH3
H
d) 4-ethyl-3,5-dimethyloctanal
CH2
O
C
CH2
CH
CH
CH3
CH
CH2
CH2
CH3
H
CH3
CH3
32. If the molecular formula is C2H4O, the compound must be an aldehyde because the oxygen will be
bonded to a terminal carbon. There are only two carbon atoms in the molecule, so both must be
terminal.
33. There are lots of ketones and aldehydes with the molecular formula C6H12O. Some are shown below,
but there are many others:
O
CH2
C
2-methyl pentanal
O
hexanal
CH2
CH2
CH2
C
CH3
H
CH
CH2
CH2
CH3
H
CH3
O
3-methyl pentanal
CH2
C
CH
O
CH2
4-methyl pentanal
CH3
C
H
CH2
CH2
CH
CH3
H
CH3
CH3
2-ethyl butanal
O
O
2,3-dimethyl butanal
C
CH
CH
CH3
CH3
C
CH3
H
O
CH3
O
C
C
2,2-dimethyl butanal
CH2
CH
CH2
CH2
CH3
CH3
H
CH3
C
2-hexanone
CH2
CH2
CH2
CH3
CH3
H
O
CH3
O
CH3
CH2
C
CH3
CH2
CH2
CH2
O
4-methyl-2-pentanone
C
CH2
CH
CH3
C
C
CH3
3,3-dimethyl-2-butanone
CH3
C
3-methyl-2-pentanone
CH
CH2
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
O
CH
3-hexanone
O
CH3
C
2-methyl-3-pentanone
CH3
Remember when naming:
• aldehydes do not need a position number for the
R-CHO group, it is always on carbon-1
• the C=O group in ketones always gets the lowest
position number, even if it means that the
position numbers for other branches are higher
Page 40 Answers to Homework on Carboxylic Acids Q 34 – 37
34a) propanoic acid
b) 2,2-dimethyl butanoic acid
c) 2-ethyl-4,5-dimethyl hexanoic acid
35a) hexanoic acid
O
O
C
CH2
CH2
CH2
CH2
CH3
OR
OH
HO
b) 3-propyloctanoic acid
O
OR
O
CH2
C
CH
CH2
CH2
CH2
CH2
CH3
HO
OH
CH2
CH2
CH3
ethyl group
c) 3,4-diethyl-2,3,5-trimethylheptanoic acid
CH3
O
CH
C
CH3
CH2
CH
C
CH3
CH
OR
CH2
O
CH3
HO
CH3
CH2
OH
CH3
37. Two carboxylic acids with molecular formula C4H8O2 (I think there are only these two):
O
O
C
HO
CH2
CH2
butanoic acid
CH3
C
CH
HO
CH3
CH3
2-methyl-propanoic acid
Page 32 Answers to Homework on Amines Q 26a,c, 27a,b, 29
26a)
b)
c)
d)
methanamine
N-ethyl-2,2-dimethyl-1-propanamine
2-butanamine
N,N-dimethylcyclopentanamine
27a)
b)
2-pentanamine
CH3
CH2
CH2
cyclohexanamine
NH2
CH3
CH
NH2
c) N-methyl-1-butanamine
CH3
NH
CH2
CH2
d) N,N-diethyl-3-heptanamine
CH2
CH3
CH3
CH2
CH
CH3
CH2
N
CH2
CH2
28a)
b)
c)
d)
CH2
CH2
CH3
CH3
2-pentanamine is a primary amine (the N has only one alkyl group attached)
cyclohexanamine is a primary amine (the N has only one alkyl group attached)
N-methyl-1-butanamine is a secondary amine (the N has two alkyl groups attached)
N,N-diethyl-3-heptanamine is a tertiary amine(the N has three alkyl groups attached)
29. All of the isomers with molecular formula C4H11N.
CH3
CH2
CH2
CH2
NH2
1-butanamine
CH3
NH
CH2
CH3
2-butanamine
CH2
CH3
NH
CH3
NH2
CH3
CH3
CH
CH
CH3
N-methyl-1-propanamine
CH3
CH2
N
N,N-dimethyl ethanamine
CH3
CH2
N-methyl-2-propanamine
CH3
CH3
CH3
CH2
CH3
CH3
CH2
C
NH
N-ethyl ethanamine
NH2
CH3
2-methyl-2-propanamine