Get documents about "Amines and Amides
Shared by: wTSxt1e
-
Stats
- views:
- 56
- posted:
- 11/24/2011
- language:
- English
- pages:
- 43
Document Sample
Amines and Amides
1
Amines
• Nitrogen containing compound
• Nitrogen is a group 5A element with 5
valence electrons
• Nitrogen has 3 bonds and 1 lone pair
• Ammonia derivatives where at least one H
is replaced by an alkyl, cycloalkyl, or aryl
group
2
Amines
• Classified as primary, secondary, tertiary
CH3 CH3
CH3—NH2 CH3—NH CH3—N — CH3
1° 2° 3°
3
Structure of Amines
Aliphatic amines Aromatic Amines
N bonded to alkyl groups N bonded to one or more
aryl groups
CH3NHCH2CH3
NH2 NH CH3
CH3
|
CH3CH2NCH3
4
Heterocyclic Amines
• Heterocyclic aliphatic • Heterocyclic aromatic
amines amines
– Ring is saturated and N – When nitrogen is part
is part of a ring of an aromatic ring
N N
N N
H H
H
N
H 5
Naming Amines
• Amines may be named using either common or
IUPAC rules
• For common names, list the alkyl groups attached
to the N in ABC order and use the suffix –amine,
which is written as one word
• Prefixes di- and tri- are used if identical groups are
present
6
IUPAC Naming of 1o Amines
1. Select the longest carbon chain that contains the N as the
parent
2. Name parent as an alkan-amine by removing the –e of the
alkane and replacing it with the suffix –amine
3. # the parent from the end nearest the N
4. The location of the amino group comes before the parent
5. If the parent is substituted, its name and # comes before
the parent
7
Examples
CH3CH2NH2
ethanamine
NH2
(ethylamine) |
CH3CHCH3
2-propanamine
(isopropylamine)
CH3CHCH2NH2
CH3
3-Methyl-1-propanamine
(Isobutylamine) 8
IUPAC Naming 1o Amines
• Compounds with 2 amino groups are named by
adding suffix -diamine. The final ‘e’ of the parent
hydrocarbon is retained
H2NCH2CH2CH2CH2CH2CH2NH2 NH2
|
1,6-hexanediamine
CH3CHCH2NH2
1,2- propanediamine
9
IUPAC Naming 2o and 3o Amines
1. 2o and 3o amines are named as N-substituted
primary amines
2. The largest alkyl chain is considered the parent
3. The other alkyl chains are placed in front of the
parent using the prefix N- to denoted that it is
attached to the N
CH3NHCH2CH3 N,N-dimethylcyclohexanamine
N- methylethanamine N(CH3)2
10
Examples
CH3—NH —CH3
N-methylmethanamine
(dimethylamine)
NH2 NH CH3
N-methylaniline
Aniline
11
Nomenclature Priority
• If other functional groups are present on an
amine, the –NH2 group is a substituent and
is called –amino
• Priority List from highest to lowest:
carboxylic acid, aldehyde, ketone,
alcohol, amine
12
Learning Check
Give the name and classify:
A. CH3NHCH2CH3
CH3
|
B. CH3CH2NCH3
13
Solution
A. CH3NHCH2CH3
N-methylethanamine , 2°
CH3
|
B. CH3CH2NCH3
N,N- dimethylethanamine , 3°
14
Learning Check
Write a structural formula for
A. 1-pentanamine
B. 1,3-cyclohexanediamine
15
Solution
A. 1-pentanamine
CH3CH2CH2CH2CH2-NH2
B. 1,3-cyclohexanediamine
N H2
NH2
16
Physical Properties
• Amines are polar compounds
• Both 1° and 2° amines form intermolecular
hydrogen bonds
• Boiling points are higher than corresponding
alkanes but lower than the corresponding alcohols
• Are soluble if 6 or less carbons are present
17
Physical Properties
•Amines are polar compounds
•3° amines have no N-H bond and cannot form
hydrogen bonds with one another
18
Boiling Points
• N-H less polar than O-H.
• Weaker hydrogen bonding.
• Tertiary amines cannot hydrogen bond.
19
Physical Properties of Amines
Boiling points of amines are higher than those of
alkanes but lower than those of alcohols
Compound Formula Mass BP(oC)
CH3CH3 30 -89
CH3NH2 31 -6
CH3OH 32 65
20
Basicity of Amines
• Lone pair of electrons on nitrogen can accept a
proton from an acid
• All amines are weak bases and aqueous
solutions of amines are basic
•• + ••
CH 3 - N - H + - •• - H
O
••
••
CH3 - N + O
H- •• - H
H H
Methylamine Methyl- Hydroxide
ammonium ion ion
21
Ammonium Salts
• When 4 atoms or groups of atoms are bonded to a
nitrogen atom, N has a positive charge (NH4+)
• The positively charged nitrogen is associated with
anion to produce a salt
CH3NH2 + HCl CH3NH3+ Cl–
methylammonium
chloride
22
Synthesis of Amines
Base H2N R
NH3 + R-X
• Alkylation R-NH2 + R'-X
Base HN R
Base H2N R
NH3 + R-X R'
HNR-NH R ++ R"-X
R'-X BaseBase R" N
HN R
R
2
R' R'
R'
R'"
R" N HN R R
+ R"'-X Base
+ R"-X Base
R" N R"
R N R
R' R'
R' R'
R'"
R" N R + R"'-X Base R" N R
R' R'
23
Neurotransmitters
• Neurotransmitter – chemical substance that is
released at the end of a nerve, travels across the
synaptic gap, and then bonds to a receptor site on
another nerve, causing a nerve impulse
OH
NH2 NH2
HO HO
Norepinephrine Dopamine
HO HO
OH
NH2
H
N N
HO
Epinephrine N Histamine
HO 24
H
Alkaloids
• Physiologically active nitrogen-containing
compounds
• Extracted from bark, leaves, berries & fruits
• Used as anesthetics, antidepressants, and
stimulants
• Many are addictive
25
Nicotine
CH3
N
Derived from tobacco leaves
Small doses – stimulant effect
Large doses – poison
Nicotine salts - insecticides
26
Caffeine
O CH3
CH3 N
N
O N N
CH3
Found in coffee beans and tea
27
Amides
• Amides – derivatives of carboxylic acids where
the –OH is replaced with an amino (-NH2) or
substituted amino group
• Are either un-, mono-, di-substituted
• Also called 1o, 2o, or 3o
• May be aromatic or cyclic (called lactams)
O
O ||
|| R — C — NH
2
R — C — OH amide 28
Amide Nomenclature
• Are named as derivatives of carboxylic acids
so the name is based on the name of a parent
acid
1. The ending of the acid is changed from –oic
acid to –amide
2. Names of groups attached to N precede the
parent with the N- prefix as the locator
29
Examples
A. Pentanamide
O
||
CH3CH2CH2CH2C–NH2
B. N-methylbutylamide
O
||
CH3CH2CH2C–NHCH3
30
Naming Amides with N- Groups
O
||
CH3C–NHCH3 N-methylethanamide
O
||
CH3CH2C–N(CH3)2
N,N-dimethylpropanamide
31
Aromatic Amides
O O
C NH2 C NHCH3
B enz amide N -methylbenz amide
32
Learning Check
Name the following amides:
O
||
A. CH3CH2CH2C–NH2
O
||
B. CH3C–N(CH2CH3)2
33
Solution
O
||
A. CH3CH2CH2C–NH2
butanamide
O
||
B. CH3C–N(CH2CH3)2
N,N-diethylethanamide;
34
Learning Check
Draw the structures of
A. Hexanamide
B. N-methylheptamide
35
Cyclic Amides
• Biologically significant lactams include
penicillin and penicillin derivatives
• such as ampicillin and amoxicillin
36
Physical Properties of Amides
• Are not basic like amines
• If they have 6 or less carbons, they are
soluble in water
• Have the ability to H-bond
37
Synthesis of Amides
O H 100oC O
N H H2O
R OH H H Catalyst R N
acid ammonia H
1 o amide
O H 100oC O
N R H2O
R OH H R Catalyst R N
acid 1o amine H
2o amide
O H 100oC O
N R H2O
R OH R R Catalyst R N
acid 2o amine R
3o amide 38
Reactions of Amides
Amides undergo
acid hydrolysis base hydrolysis
carboxylic acid + salt of carboxylic acid
ammonium salt + amine
39
Reactions of Amides
acid hydrolysis
O
||
HCl + H2O RCOH + NH4+Cl–
O
||
RCNH 2 Heat
O
||
RC O– Na+ + NH3
NaOH
base hydrolysis
40
Learning Check
Hydrolysis of N-ethylpropanamide with NaOH
gives what products.
41
Solution
Hydrolysis of N-ethylpropanamide with NaOH
gives the following products.
O
||
CH3CH2CO– Na+ + CH3CH2NH2
42
Polyamides
43
