AMINES, AMIDES and AMINO ACIDS
1. Amines Physical Properties of Amines
2. Amides • Small amines are gaseous and soluble in water.
3. Amino Acids • Have bad smell like tainted fish.
4. Peptide Formation and Proteins • Polar compounds.
Warm Up • Primary and secondary amines have hydrogen bond
List down some nitrogen based organic compounds with their therefore their boiling points are higher than that of
properties. equivalent ether and alkanes. Tertiary amines do not have
What do you remember when you heard about words “amino N-H bond so they have lower boiling points.
acid”. Chemical Properties of Amines
Amines • They are basic compounds, form hydrogen bonds upon
• Are organic derivatives of ammonia or alkylated ammonia dissolving in water.
compounds. • Order of basic strength is R3N>R2NH>RNH2>NH3
• Functional group is amino group, –NH2 Preparation of Amines
• They can be primary, secondary or tertiary according to • Reactions of ammonia with alkyl halides produce ammonium
number of alky group. salts, and treating these ammonium salts with bases yields
• - R group can be aromatic. primary amines.
Preparation of Amines
NH3 + R-X → RNH2 (primary amine)
If primary amines react with alkyl halides, secondary amines are
produced.
Almost all organic compounds containing nitrogen can be reduced to
amines.
C2H5-NO2 + 3H2 → C2H5-NH2 + 2H2O
Common Amines
Nomenclature of Amines Amines that are isolated from plants are known as alkaloids.
• For small or primary amines common names are often used. Nicotine has a pleasant, invigorating
effect when taken in minuscule
quantities, but is extremely toxic in
larger amounts.
• For secondary and tertiary amines the smaller group is Strychnine is another toxic alkaloid that
written first. If the groups are identical –di and –tri prefixes has been a popular poison in murder
are used. Locant N is used to designate the groups bonded mysteries.
to nitrogen atom.
Coniine is the active ingredient in
hemlock, a poison that has been used
since the time of Socrates.
Caffeine is the pleasantly addictive
substance that makes a cup of coffee an
• For some molecules containing alcohol or carboxylic acid important part of the day for so many
groups IUPAC system is used. Amino group becomes people.
substituent.
2. Amides
• Amides are derived from ammonia by replacing a hydrogen
with an organic acid group.
• Amides can be classified as primary, secondary and tertiary • It is found in the blood of mammals, used as a fertilizer as
according to the number of alkyl groups attached to the –N nitrogen source, and in plastic manufacturing.
atom. • It is first produced by the reaction of ammonia with CO2 at
high pressure. It can be obtained from phosgene as well.
Nomenclature of Amides
• For the simplest (primary) amides use the name of the
carboxylic acid and replace –ic with –oic suffix with –amide.
3. Amino Acids
• They contain both amino (-NH2) and carboxyl (-COOH)
groups.
• They are basic building blocks of living organisms.
For the secondary and tertiary use N locant for the groups bonded to
NH2 group
Nomenclature of Amino Acids
• They are named according to position of functional groups.
Properties of Amides
• They have hydrogen bonds therefore their boiling points are Properties of Amino Acids
relatively high. • Because there are both amino and carboxyl groups in amino
• They are water soluble compounds. acids they are amphoteric substances. (have both acidic and
• They do not react with acids and bases. basic characters)
Preparation of Amides • They form metal salts with basic solutions.
• They can be prepared by the reaction of ammonia, primary • They behave as bases towards acidic solutions.
amines or secondary amines with acid anhydrides, esters or • In solid state, they form Zwitterion.
acyl chlorides.
Preparation of Primary Amides
4. Peptide Formation and Proteins
• Proteins are the largest and most complicated molecules
that exist in the cells of living organisms.
Preparation of Secondary Amides • They are polymers of amino acid units These units are
bonded together by a peptide linkage.
• Peptides are amides formed by the reaction of amino groups
with the carboxyl groups of amino acids.
• According to number of amino acid unit they are classified as
dipeptides, tripeptides and polypeptides.
Preparation of Tertiary Amides
• If the number of amino acid forming peptide bonds is more
than 12000 it is called protein.
• Proteins are used for repairing degenerated tissue in living
Urea (Carbamide) organisms. DNA and RNA are also proteins.
• It is colorless, water soluble and crystalline solid with a
o
melting point of 132 C.