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Chapter 16,17 & 18
Amines, Aldehydes, Ketones and Carboxylic Acids
Chemistry B11
Amines
Amines:
• Are derivatives of ammonia NH3.
• Contain N attached to one or more alkyl (Aliphatic amine) or aromatic groups (Aromatic amine).
CH3-NH2 CH3-NH-CH3
Amines
-NH2 amino group
CH2CH3 CH3 CH=CH2
TolueneEthylbenzene Styrene
NH2
Amines are classified into three groups:
depending on the number of carbon groups bonded to nitrogen.
CH3 CH3
CH3—NH2 CH3—NH CH3—N—CH3
Amines
Primary 1° Secondary 2° Tertiary 3°
Naming Amines
The same method as we did for alcohols.
- Drop the final “-e” of the parent alkane and replace it by “-amine”.
- Use a number to locate the amino group (-NH2) on the parent chain.
IUPAC name – 1° amines
CH3CHCH3
NH2
NH2
H2NNH2
1,6-HexanediamineCyclohexanamine2-Propanamine
CH3-CH-CH3
NH2
2-propanamine
CH3-CH-CH-CH3
NH2
Cl
3-chloro-2-butanamine 1,6-hexanediamine
123 1 2
3
4
1234
56
Common name
Names of alkyl groups (In alphabetical order) + “amine”
CH3—CH2—NH2 ethylamine
CH3—NH —CH3 dimethylamine
CH3
|
CH3—N—CH2—CH3 ethyldimethylamine
Naming Amines
CH2CH3 CH3 CH=CH2
TolueneEthylbenzene Styrene
CH2CH3 CH3 CH=CH2
TolueneEthylbenzene Styrene
CH2CH3 CH3 CH=CH2
TolueneEthylbenzene Styrene
Aniline (common name)
NO2
CH3 CH3
Aniline
4-Nitroaniline 3-Methylaniline 4-Chloro-3-methylaniline
NH2
NH2NH2 NH2
Cl
1 2
3
4
1 2
3
1 2
34
CH2CH3 CH3 CH=CH2
TolueneEthylbenzene Styrene
Naming Amines
– Take the largest group bonded to nitrogen as the parent amine.
– Name the smaller group(s) bonded to nitrogen, and show their locations on nitrogen by using the prefix “N”.
IUPAC name – 2° and 3° amines
NCH3
CH3
NHCH3
N,N-Dimethyl- cyclopentanamine
N-Methylaniline
NCH3
CH3
NHCH3
N,N-Dimethyl- cyclopentanamine
N-Methylanilineaniline
CH3-N-CH2-CH3
CH3
N,N-Dimethylethanamine
Heterocyclic amines
When N is one of the atoms of a ring.
N
HHCH3
Pyrrolidine Pyridine Nicotine
Physical properties of Amines
1. They have unpleasant odors (rotting fish like ammonia).
2. They are polar compounds.
Difference in electronegativity between N - H (3.0 – 2.1 = 0.9)
3. 1° and 2° amines have hydrogen bonds (N-H).
Weaker than alcohols (O-H).
3° amines do not form hydrogen bonds (no H atom).
4. Boiling points: Hydrocarbons< Amines < Alcohols
5. Almost soluble in water (hydrogen bonding).
Chemical properties of Amines
They are weak bases (like ammonia): react with acids.
N
H
H
CH3 .. + H – O – H....N
H
H
CH3 H+
O – H......
-
Some amines present in our blood and make it approximately basic (pH = 7.4).
(to form water-soluble salts)
Chemical properties of Amines
C6H5NH2
CH3CH2NH2Aliphatic
Ammonia
Aromatic
3.0 - 4.0
4.74
8.5 - 9.5
Class pKb Example Name
Ethanamine
Aniline
Stronger base
Weaker base
Aliphatic amines are weak bases by comparison with inorganic bases
such as NaOH, they are strong bases among organic compounds.
Aliphatic amines are stronger bases than aromatic amines.
(slightly stronger than NH3)
Complete each acid-base reaction and name the salt formed.
(CH3CH2)2NH HCl
NCH3COOH
+(a)
(b) +
Examples
Complete each acid-base reaction and name the salt formed.
Examples
Solutions:
(CH3CH2)2NH HCl
NCH3COOH
NH
(CH3CH2)2NH2+Cl-
CH3COO-
Diethylammoniumchloride
+Pyridinium acetate
+(a)
(b) +
Aldehydes
Ketones
Carbonyl group
C
=O
Aldehydes Ketones Carboxylic acids Esters
CH3COCH2CH3
ONaOH
H2OCH3CO-Na+
O
CH3CH2OH
Sodiumhydroxide
+ +
Ethyl acetate Sodiumacetate
Ethanolheat
• In an aldehyde, at least one H atom is attached to a carbonyl group.
• In a ketone, two carbon groups are attached to a carbonyl group.
Aldehydes and Ketones
C=O
Step 1Select the longest carbon chain
that contains the carbonyl group (C=O).
Step 2Number from the end nearest C=O group.
Step 3Change the ending of parent alkane from -e to -al.No number for carbonyl group C=O (it always comes first).
Step 4Give the location and name of each substituent
(alphabetical order) as a prefix to the name of themain chain.
Naming Aldehydes
• Common names for the first two aldehydes use the prefixes “form” (1C) and “acet” (2C) followed by “aldehyde”.
O O O ║ ║ ║
H─C─H CH3─ C ─H CH3─CH2─ C ─H methanal ethanal propanal(formaldehyde) (acetaldehyde)
Naming Aldehydes
O ║CH3─CH─CH2─ C─H 3-Methylbutanal
O
║ Cl─CH2─CH2─ C─H 3-chloropropanal
CH3
1234
123
Step 1Select the longest carbon chain
that contains the carbonyl group (C=O).
Step 2Number from the end nearest C=O group.
Step 3Change the ending of parent alkane from -e to -one.
Use the number to show the location of C=O.
Step 4Give the location and name of each substituent
(alphabetical order) as a prefix to the name of themain chain.
Naming Ketones
Naming Ketones
• In the common name, name the “alkyl groups” alphabetically attached to the carbonyl group and add the word “ketone”.
O O
║ ║
CH3 ─ C ─CH3 CH3─C─CH2─CH3
propanone 2-butanone
(dimethyl ketone) (ethyl methyl ketone)
1 2 3 4
O
Acetone 2-Methylcyclohexanone5-Methyl-3-hexanone
OO
12
34
56
12
O
Acetone 2-Methylcyclohexanone5-Methyl-3-hexanone
OO
12
34
56
12
CH
O
Benzoic acidBenzaldehyde
+ O2
COH
O
2 2
3-ChloroO
Acetone 2-Methylcyclohexanone5-Methyl-3-hexanone
OO
12
34
56
12
O
Acetone 2-Methylcyclohexanone5-Methyl-3-hexanone
OO
12
34
56
12O
Acetone 2-Methylcyclohexanone5-Methyl-3-hexanone
OO
12
34
56
12
CH
O
Benzoic acidBenzaldehyde
+ O2
COH
O
2 2
Cl
O
H
OOH
NH2
3-Hydroxy-4-methylpentanal 3-Amino-4-ethyl-2-hexanone
1345 12346
O
H
OOH
NH2
3-Hydroxy-4-methylpentanal 3-Amino-4-ethyl-2-hexanone
1345 12346
O
H
OOH
NH2
3-Hydroxy-4-methylpentanal 3-Amino-4-ethyl-2-hexanone
1345 12346
O
H
OOH
NH2
3-Hydroxy-4-methylpentanal 3-Amino-4-ethyl-2-hexanone
1345 12346
3-Methylbutanal 2-Propenal(Acrolein)
Hexanal
12
34H
O
H
O1
23
45
6
123
H
O3-Methylbutanal 2-Propenal
(Acrolein)Hexanal
12
34H
O
H
O1
23
45
6
123
H
O
Physical properties of Aldehydes and Ketones
1. They have strong odors (ketones have pleasant odors).
2. They are polar compounds.
3. Only dipole-dipole interactions (no hydrogen bonding).
4. Low boiling points compare to amines and alcohols.
5. Soluble in water (no soluble in nonpolar compounds).
δ+
δ-
δ+
δ-H
OHδ+
Hydrogen bond with water.
Higher than hydrocarbons.
C-O 3.5-2.5 = 1
Chemical properties of Aldehydes and Ketones
1. Oxidation: only for aldehydes (not for ketones).
K2Cr2O7
H2SO4
CH3─CH2─CH2─CH2─C─OH
=
O
CH3─CH2─CH2─CH2─C─H
=
O
Pentanal Pentanoic acidK2Cr2O7: Oxidizing agent
CH
O
Benzoic acidBenzaldehyde
+ O2
COH
O
2 2Liquid aldehydes
are sensetive to oxidation.
No oxidizing agent
Chemical properties of Aldehydes and Ketones
2. Reduction:
Like reducing the alkene (C = C) to alkane (C – C):
– Reduction of an aldehyde gives a primary alcohol (-CH2OH).
– Reduction of a ketone gives a secondary alcohol (-CHOH-).
H2
tran sition
metal catalyst+
1-Pen tan ol
CH3─CH2─CH2─CH2─C─ H
=
O
PentanalCH3─CH2─CH2─CH2─CH2─ OH
H2
tran si tion
metal cataly st+CH3─C─CH2─CH3
=
O
CH3─CH─CH2─CH3
-OH
2-butanol2-butanone
O NaBH4O-
HH3O+ O-H
H
H - C O H C O - H3O+
H C O-H: +
Hydrideion
Chemical properties of Aldehydes and Ketones
Reduction mechanism:
NaBH4 Sodium borohydride: produces hydride ion: H-
-
Reducing agent
Carboxylic Acids
A carboxylic acid contains a carboxyl group, which is a carbonyl group attach to a hydroxyl group.
carbonyl
group
O
CH3 — C—OH hydroxyl group or CH3COOH
carboxyl group
Carboxylic Acids
CH3CO2H
• In the IUPAC name of carboxylic acids, the “-e” in the name of the longest chain is replaced by “-oic acid”.
• The common names use prefixes “form-” and “acet-” for the first
two carboxylic acids.
H-COOH methanoic acid formic acid
CH3-COOH ethanoic acid acetic acid
CH3-CH2-COOH propanoic acid
CH3-CH2-CH2-COOH butanoic acid
Naming Carboxylic Acids
Naming Carboxylic Acids
– Number the chain beginning with the carbon of the carboxyl group.
– Because the carboxyl carbon is understood to be carbon 1, there is no need to give it a number.
13
3-Methylbutanoic acid
OH
OOHH2N COOH15
4-Aminobenzoic acid5-Hydroxylhexanoic acid
4
CH3─CH2─CH─COOH
CH2 – CH3
2-Ethylbutanoic acid
2CH3─CH─CH2─COOH
CH3
1
1
Naming Dicarboxylic Acids
– Add the suffix “-dioic acid”dioic acid” to the name of the parent alkane that contains both carboxyl groups; thus, “-ane”ane” becomes “-anedioic acid”anedioic acid”.
– The numbers of the carboxyl carbons are not indicated because they can be only at the ends of the chain.
O
HOOH
O
HO OH
O
OOH
O
OH
O
O
HO
O
HO
1 1
1 1
2 3
4 6OH
O
HO15
O
Ehanedioic acid Propanedioic acid
Butanedioic acid Pentanedioic acid Hexanedioic acid
Physical properties of Carboxylic Acids
1- The carboxyl group contains three polar covalent bonds;
C=O, C-O, and O-H. So they are so polar.
2- Carboxylic acids have higher boiling points than other types of organic compounds (with the same molecular weight) because of hydrogen bonding.
3- They are more soluble in water than alcohols, ethers, aldehydes, and ketones because of stronger hydrogen bonding.
4- Liquid carboxylic acids have sharp and disagreeable odors.
5- They taste sour (exist in pickle, lime, and lemon).
H3C C
O
O
H
CH3C O
O
H- +
+ -
Hydrogen bondingbetween two molecules
Fatty Acids
• Long, unbranched chain carboxylic acids and they are found in animal fats, vegetable oils, or phospholipids of biological membranes.
• Most have between 12 and 20 carbons in an unbranched chain.
• In most unsaturated fatty acids, the cis isomer is usually existed and the trans isomer is rare.
• Unsaturated fatty acids have lower melting points than their saturated counterparts.
COOH
COOH
COOH
COOH
Stearic acid (18:0)(mp 70°C)
Oleic acid (18;1)(mp 16°C)
Linoleic acid (18:2)(mp-5°C)
Linolenic acid (18:3)(mp -11°C)
COOH
COOH
COOH
COOH
Stearic acid (18:0)(mp 70°C)
Oleic acid (18;1)(mp 16°C)
Linoleic acid (18:2)(mp-5°C)
Linolenic acid (18:3)(mp -11°C)
Cis
Fatty Acids
Saturated fatty acids are solids at room temperature.
COOH
COOH
COOH
COOH
COOH
Packed together Maximum London dispersion forces
Fatty Acids
Unsaturated fatty acids are liquids at room temperature.
Can not packed together London dispersion forces
COOH
COOH
COOH
COOH
COOH
Cis
In an ester, the H in the
carboxyl group is replaced
by an alkyl group.
O
CH3 — C—O —CH3
ester group
Esters
• Natural soaps are sodium or potassium salts of fatty acids.
• They are prepared from a blend of tallow and coconut oils (triglycerides).
• Triglycerides are triesters of glycerol.
• the solid fats are melted with steam and the water insoluble triglyceride layer that forms on the top is removed.
Soaps
CH2 – CH – CH2
OH OHOH
1,2,3-Propanetriol(glycerol, glycerin)
• Preparation of soaps begins by boiling the triglycerides with NaOH. The reaction that takes place is called saponification.
• Boiling with KOH gives a potassium soap.
Soaps
Sodium soaps1,2,3-Propanetriol(Glycerol; glycerin)
A triglyceride( a triester of glycerol)
+saponification
+
CH2OCR
CH2OCR
CHOH
CH2OH
CH2OH
RCOCH 3NaOH 3RCO-Na
+O
O
O
O
Sodium soaps1,2,3-Propanetriol(Glycerol; glycerin)
A triglyceride( a triester of glycerol)
+saponification
+
CH2OCR
CH2OCR
CHOH
CH2OH
CH2OH
RCOCH 3NaOH 3RCO-Na
+O
O
O
O
Sodium soaps1,2,3-Propanetriol(Glycerol; glycerin)
A triglyceride( a triester of glycerol)
+saponification
+
CH2OCR
CH2OCR
CHOH
CH2OH
CH2OH
RCOCH 3NaOH 3RCO-Na
+O
O
O
O
Soaps
Hydrophobic part: nonpolar
Hydrophilic part: polar (remains in contact with environment)
When soap is mixed with dirt (grease, oil, and …), soap
micelles “dissolve” these nonpolar, water-insoluble molecules.
Soaps
Chemical properties of Carboxylic Acids
1- They are weak acids.
Substituents of high electronegativity, especially -OH, -Cl, and -NH3+, near
the carboxyl group increase the acidity of carboxylic acids.
2- Reaction with bases:
They react with NaOH, KOH, NH3, and other strong bases to form water-soluble salts.
COOH NaOHH2O
COO- Na
+H2O+ +
Benzoic acid(slightly soluble in water)
Sodium benzoate(60 g/100 mL water)
COOH NH3H2O
COO- NH4
++
Ammonium benzoate(20 g/100 mL water)
Benzoic acid(slightly soluble in water)
Chemical properties of Carboxylic Acids
3- Fischer Esterification:
- A carboxylic acid reacts with an alcohols to form an ester.
- Using an acid catalyst such as concentrated sulfuric acid.
CH3C-OHO
H-OCH2CH3
H2SO4CH3COCH2CH3
OH2O
Ethanoic acid(Acetic acid)
++
Ethyl ethanoate(Ethyl acetate)
Ethanol(Ethyl alcohol)
The best way to prepare an ester.