Download AMIDES AND AMINES: ORGANIC NITROGEN COMPOUNDS

CHAPTER 25
AMIDES AND AMINES: ORGANIC NITROGEN COMPOUNDS
SOLUTIONS TO REVIEW QUESTIONS
1.
Table 25.1 incorrectly reports acetaminophen’s boiling point as 169°C (this is actually the
melting point for this drug). The lowest boiling point amide in the table is methanamide
(formamide), b.p. = 210°C.
O
HC
NH 2
N-phenylethanamide (acetanilide), b.p. = 304°C.
The highest boiling point amide is N
O
CH3C
H
N
N-phenylethanamide contributes significantly to its higher boiling
The larger size of N
point.
2.
Procaine contains an amine. When the amine reacts with HCl it forms a salt that is much
more soluble in water.
3.
(a)
(b)
(c)
(d)
4.
With reference to Section 25.6, acetylcholine contains a quaternary (4°) amine.
With reference to Section 25.8, cocaine contains a tertiary (3°) amine.
With reference to Section 25.7, serotonin contains a primary (1°) and a secondary
(2°) amine.
With reference to Section 25.8, methamphetamine contains a secondary (2°) amine.
Amides: Unsubstituted amides (except formamide) are solids at room temperature. Many
are odorless and colorless. Low molar-mass amides are water soluble. Solubility in water
decreases as the molar mass increases. Amides are neutral compounds. The
group is
capable of hydrogen bonding.
Amines: Low molar-mass amines are flammable gases with an ammonia-like odor.
Aliphatic amines up to six carbon atoms are water soluble. Many amines have a “fishy”
odor and many have very foul odors. Aromatic amines occur as liquids and solids.
Soluble aliphatic amines give basic solutions. Aromatic amines are less soluble in water
and less basic than aliphatic amines. The
group is capable of hydrogen bonding.
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5.
Unlike esters, unsubstituted amides can hydrogen bond to each other. Thus, they have a
higher melting point than esters of similar molar mass.
6.
(a)
(b)
7.
Ammonia is a toxic, basic, water soluble compound which can increase the pH of the
blood and the urine and would be painful to pass through bodily tissues. However,
ammonia is converted in the liver to the neutral diamide, urea, which is water soluble and
is excreted in the urine.
8.
A “condensation polymer” is made when monomers connect together with the loss of a
small molecule, most often, water.
Heterocyclic compounds are those in which all the atoms in the ring are not alike.
The number of heterocyclic rings in each of the compounds is:
(i) purine, 2
(ii) ampicillin, 2
(iii) methadone, 0
(iv) nicotine, 2
HOOC ¬ (CH 2)4 ¬ COOH + H 2N ¬ (CH 2)6 ¬ NH 2 ¡
O
[
9.
10.
C
O
(CH2)4
C
NH
(CH2)6
NH
[
n
+ H2O
The nitrogen in a compound that has four groups bonded to it is positively charged and is
called a quaternary ammonium nitrogen. The compound is called a quaternary
ammonium salt.
An amine must have at least one hydrogen atom bonded to the nitrogen atom to react
with an acid chloride. A tertiary amine does not meet this requirement.
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SOLUTIONS TO EXERCISES
O
O
1.
(a)
C
CH3
(b)
(c)
NH 2
CH3CH2
C
CH3
O
O
CH3 CH2C
(d)
NH2
C
CH3CH
C
NHCH3
NH2
CH3
2.
(a)
CH3 CH2 CH2 CH2
O
CH3
C
N
CH3
O
(b)
CH3
C
NH2
CH3 CH3 O
(c)
CH3 CH2
CH
CH
C
NH2
O
(d)
C
NH
CH2 CH3
3.
(a)
(b)
(c)
common, formamide; IUPAC, methanamide
N N-dimethyl-3,3-dimethylbutanamide
N
IUPAC, N,
N
IUPAC, N-butylethanamide
4.
(a)
(b)
(c)
IUPAC, benzamide
N N-dibutylethanamide
N
IUPAC, N,
N-methylacetamide, IUPAC, N-methylethanamide
N
common, N
5.
N N-diethylN
The larger amides are less water soluble. Thus, the largest amide, N,
3-methylhexanamide is the least water soluble. The intermediate sized amide,
3-methylhexanamide will be of intermediate solubility and the smallest amide, acetamide,
will be the most water soluble.
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6.
The larger amides are less water soluble. Thus, the largest amide, benzamide, is the least
water soluble. The intermediate sized amide, propanamide, will be of intermediate
solubility and the smallest amide, formamide, will be the most water soluble.
H
7.
O
N
C
CH3CH2
N
H
O
H
C
CH2 CH3
H
O
C
CH3 CH2
N
H
H
H
8.
O
N
C
CH3
N
H
O
H
C
CH3
H
O
C
CH3
N
H
H
9.
Organic products
O
‘
+
(a)
3
3
3
(c) H 2NCH 2CH 2CH 2CH 2COONa
(b)
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O
‘
CH 3C ¬ NHCH(CH 3)2
- Chapter 25 -
10.
Organic products
O
‘
(a)
3
(c)
CH2COOH
2
(b)
3 2
±
± CH3NH2CH3
O
‘
C
H
C
CH
3
2 ¬ NHCH 3
ƒ
CH 3
O
11.
12.
CH3CH2CH2C
(b)
O
‘
CH 3CH 2C ¬ OH + NH 2CH 2CH 3
(c)
O
‘
HC ¬ NH ¬
(a)
(b)
(c)
13.
OH + NH2CH3
(a)
± HCl+H2O
O
‘
CH 3C ¬ NHCH 2CH 3 + NaOH
O
‘
CH 3CH 2C ¬ OH + CH 3NHCH 3
O
‘
CH 3C ¬ NH 2 + HCl + H 2O
Structures of amines with formula C4H 11N.
CH 3CH 2CH 2CH 2NH 2
1°
CH 3
ƒ
CH 3CNH 2
ƒ
CH 3
1°
CH 3CHCH 2NH 2
ƒ
CH 3
1°
CH 3CH 2CHCH 3
ƒ
NH 2
1°
CH 3CH 2CH 2NHCH 3
(CH 3)2CHNHCH 3
2°
2°
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- Chapter 25 -
13.
(cont.)
CH 3
ƒ
CH 3CH 2NCH 3
3°
CH 3CH 2NHCH 2CH 3
2°
14.
Structures of amines with formula C3H 9N.
CH 3CH 2CH 2NH 2
1°
15.
16.
CH 3CHCH 3
ƒ
NH 2
1°
CH 3CH 2NHCH 3
2°
CH 3NCH 3
ƒ
CH 3
3°
Classification of amines
(a) primary
(b)
tertiary
(c)
primary
(d)
both primary
Classification of amines
(a) secondary
(b)
tertiary
(c)
secondary
(d)
tertiary
17.
The triethylamine solution in 1.0 M NaOH would have the more objectionable odor
because it would be in the form of the free amine, while in the acid solution the amine
would form a salt that will have little or no odor.
18.
The isopropylamine solution in 1.0 M KOH would have the more objectionable odor
because it would be in the form of the free amine, while in the acid solution the amine
would form a salt that will have little or no odor.
19.
Names
(a)
dimethylamine
CH2CH3
(b)
o-ethylaniline
NH2
(c)
NH2
(d)
+
(e)
cyclohexanamine
tetraethylammonium iodide
m-nitroaniline
NH2
NO2
(f)
(CH3CH2)2N ¬
cyclohexyldiethylamine
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20.
Names
NHCH2CH3
(a)
(b)
3
2
ƒ
NH 2
NH
(c)
(f)
21.
2-butanamine
diphenylamine
+
(d)
(e)
3
N
N-ethylaniline
ethylammonium bromide
N
pyridine
O
‘
CH 3C ¬ NHCH 2CH 3
N
N-ethylacetamide
Structural formulas
(a) CH 3CH 2NHCH 3
(b)
(c)
(d)
NH2
H 2NCH 2CH 2CH 2CH 2NH 2
CH 3CH 2NCH(CH 3)2
ƒ
CH 3
(e)
N
(f)
22.
+
(CH 3CH 2)3NHCl-
Structural formulas
(a) CH 3CH 2CH 2CH 2NCH 2CH 2CH 2CH 3
ƒ
CH 2CH 2CH 2CH 3
(b)
±
¬ NH2Cl
ƒ
CH3
–
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- Chapter 25 -
(c)
(d)
23.
+
CH 3CH 2NH 3ClCH 3CH 2CH 2CHCH 2OH
ƒ
NH 2
(e)
CH3
ƒ
CH3CH2CH2C ¬¬ CH ¬ NH ¬
ƒ
ƒ
CH3 CH3
(f)
H 2NCH 2CH 2NH 2
(a)
Butylamine has the following structure:
CH3CH2CH2CH2NH2
Its IUPAC name is 1-butanamine.
tert-butylamine has the following structure:
(b)
CH3
CH3
C
NH2
CH3
(c)
Its IUPAC name is 2-methyl-2-propanamine.
Formamide has the following structure:
O
HC
NH2
Its IUPAC name is methanamide.
24.
(a)
Isopropylamine has the following structure:
CH3
CH3C H NH2
(b)
Its IUPAC name is 2-propanamine.
Diethylamine has the following structure:
CH3CH2NHCH2CH3
Its IUPAC name is N-ethylethanamine.
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- Chapter 25 -
(c)
Acetamide has the following structure:
O
CH3C
NH2
Its IUPAC name is ethanamide.
25.
(a)
This reaction adds methyl groups to a primary amine to form a tertiary amine.
CH3 CH3
CH3
C
N
CH3
CH3
(b)
N,N-dimethyl-2-methyl-2-propanamine
N
N
This reaction reduces the nitro group to form a substituted aniline.
NH2
CH3
(c)
(d)
26.
(a)
(b)
m-methylaniline
This reaction reduces the nitrile to form an amine.
CH3NH2
menthanamine (methylamine)
This reaction reduces the amide to form an amine.
CH3CH2NHCH2CH3
N-ethylethanamine (diethylamine)
N
This reaction reduces an amide to form an amine.
(CH3)3N
NN
N,
N-dimethylmethanamine (trimethylamine)
This reaction reduces a nitrile to form an amine.
CH3
CH3 CH2 CH CH2 NH2
2-methyl-1-butanamine
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- Chapter 25 -
(c)
This reaction reduces a nitro group to form a substituted aniline.
NH2
CH3
CH3
3,4-dimethylaniline
27.
(d)
This reaction adds a methyl group to a primary amine to form a secondary amine.
CH3CH2NHCH3
N-methylethanamine (methylethylamine)
N
(a)
A carboxylic acid chloride reacts with an amine to form an amide (and an amine salt).
O
CH3C
NHCH2CH2CH3 + CH3CH2CH2NH3Cl
N-propylethanamide
propylammonium chloride
(b)
(c)
An amine plus a strong acid forms an amine salt.
+
–
CH3CH2CH2CH2NH3Cl
butylammonium chloride
This reaction reduces an amide to form an amine.
CH3CH2NH2
ethanamine (ethylamine)
28.
(a)
This reaction reduces a nitrile to form an amine.
CH3
CH3 CH2 CH CH2 NH2
(b)
2-methyl-1-butanamine
A carboxylic acid chloride reacts with an amine to form an amide (and an amine salt).
O
HC
NHCH3 + CH3NH3 Cl
N-methylmethanamide
methylammonium chloride
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- Chapter 25 -
(c)
An aniline plus a strong acid forms an aniline salt.
NH3 Br
anilinium bromide
29.
Amines are bases while carboxylic acids and phenols are acids. Alcohols and amides are
neither acids nor bases.
(a) amine, base
(b) amide, neither
(c) amide, neither
(d) carboxylic acid, acid
(e) alcohol, neither
(f) alcohol, neither
30.
Amines are bases while carboxylic acids and phenols are acids. Alcohols and amides are
neither acids nor bases.
(a) alcohol, neither
(b) carboxylic acid, acid (c) amide, neither
(e) amine, base
(f) phenol, acid
(d) amine, base
31.
The main reason why trimethylamine has a lower boiling point than propylamine and
ethylmethylamine is that trimethylamine cannot hydrogen bond because it has no
hydrogen atoms bonded to the nitrogen atom. The other two amines do have hydrogen
atom(s) bonded to the nitrogen atom and their molecules can hydrogen bond, which
results in higher boiling points.
32.
Biogenic amines are derived from amino acids and act as neurotransmitters and hormones
in animals. In contrast, alkaloids are basic compounds derived from plants that show
physiological activity.
33.
This calculation requires Avogadro’s number, 6.02 × 1023 dopamine molecules/mole.
(5 × 10–18 moles)(6.02 × 1023 dopamine molecules/mole) = 3 × 106 dopamine molecules
About three million dopamine molecules are sent from one neuron to the next.
O
34.
(a)
CH3 C
O
Cl + 2 CH3 NH2
CH3 C
+
NHCH3 + CH3 NH3 Cl
O
LiAlH4
CH3 CH2 NHCH3
(b)
CH3 C
(c)
CH3 CH2 NHCH3 + CH3 Br (1 mole)
NHCH3
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CH3 CH2 N(CH3 )2
- Chapter 25 -
35.
There is one amine and two amides in ampicillin.
S
CH C
CH3
CH3
NH
N
NH2 O
COOH
O
amine
amides
36.
Lemon juice, being acidic, will react with the basic amines forming salts, which are
soluble and can be washed away with water.
NH2
37.
±
NH3Cl
± HCl ¡
–
38.
H 2N ¬ CH 2CH 2CH 2CH 2 ¬ NH 2
Putrescine has two primary amines.
39.
Drugs are given as ammonium salts because the salts are soluble in water.
40.
CH2
O
ƒ
‘
H2NCHC ¬ NHCHC ¬ OCH3
ƒ
‘
O
CH2COOH
amine
Aspartame
amide
41.
¬C¬
‘
O
¬ C ¬ NH ¬
‘
O
¬ NH ¬ C ¬
‘
O
¬ C ¬ NH ¬
‘
O
Kevlar polymer
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¬ NH ¬
n
- Chapter 25 -
42.
43.
(b)
O
O
‘
‘
HO ¬ C ¬ (CH 2)8C ¬ OH
O
O
‘
‘
HO ¬ C ¬ (CH 2)6C ¬ OH
(a)
CH 3CH 2OH
(a)
KCN
H 2SO4
140°C
and
H 2N(CH 2)6NH 2
H2N ¬
and
" C H “ CH
2
2
" NCCH CH CN
2
2
H2
Ni
Br2
¬ CH2 ¬
¬ NH2
" BrCH CH Br
2
2
" H NCH CH CH CH NH
2
2
2
2
2
2
1,4-butanediamine
(b)
O
O
‘
‘
LiAlH 4 "
CH 3C ¬ Cl + NH 3 ¡ CH 3C ¬ NH 2
CH 3CH 2NH 2
O
O
‘
‘
LiAlH 4 "
CH 3C ¬ Cl + CH 3NH 2 ¡ CH 3C ¬ NHCH 3
CH 3CH 2NHCH 3
O
O
‘
‘
LiAlH 4 "
CH 3C ¬ Cl + (CH 3)2NH ¡ CH 3C ¬ N(CH 3)2
CH 3CH 2N(CH 3)2
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