3. FUNCTIONAL GROUP
Definition:
the functional group is define as,
‘An atom or group of atoms joined in
specificmanner which gives the chemical
properties of the organic compounds and are
the center for
chemical reactivity.’
4. Compounds having a
similar functional group
have under gone
similar reactions
The presence of functional
groups enables the
systematization of organic
compound into different
classes
Examples
alkene, alcohols,
carboxylic group,
amines and amides etc
5. Amides
Definition
‘ An amide is a functional group in
which a carbonyl group
is linked to a nitrogen atom .’
Amide linkage is in a
biochemical context
is called peptide bond
7. CHARACTERISTICS
amides are derived from carboxylic acid
amides are amphoteric in nature
REASONS:
Lone pair present in nitrogen of amides is involving in
resonance and less available for donating. Hence ,behave
as weak base.
During resonance it forms positive charge on nitrogen
which has tendency to lose proton and behave as acid.
8. POINT TO PONDER
cyclic amide are called “lactams” ; they
are necessarily secondary or Tertiary amides .
Functional groups consisting PHOSPHOAMIDES
[P(O)NR2] and sulfonamides
[SO2NR2]
9. Nomenclature ;
In the usual nomenclature we
add the term “amide” to the stem of the parent acid’s
name .
EXAMPLE ;
the amide derived from acetic acid is named as
acetamide CHзCONH2
IUPAC ;
IuPAC recomand it as ethanamide
.Amide take the suffix “amide” to the alkane chain of the
carbons . If amides have additional substituents on the
nitrogen then name them “ Alphabetically “
10. PHYSICAL PROPERTIES
THE amides generally have high melting and boiling
points.
Their polar nature in water result from the polar nature
of the amide group and hydrogen bonding.This hydrogen
bonding affect their chemical and physical properties to
great extent.
They are present in solids, liquids,and even crystalline
form.
Solid(stearamide), liquid(formamide),and
crystal(choroacetamide).
11. CONTINUED
Methanamide is a liquid at room
temperature,but other simple amines
are solids.
Ethanamide is said to have smell like of
mice.Infact,the smell is due to impurity
called N-
methylethanamide.(CHзCOHCHз)
15. PREPARATIONS
AMIDES undergo many chemical reactions,although they are less
reactive than esters.Amides are also versalite precursors to many
other functional group……
NUCLEOPHILIC ACYL SUBSTITUTION:
GENERIC MECHANISM:BASIC HYDROLYSIS
It represent a type of reactions in which nucleophile and acyl
compounds react to form amide.
R–CO–CL + R––NH2 →
R–CO–NH–R + HCL
16. PARTIAL HYDROLYSIS OF NITRILES
NITRILES can be converted to primary amines under
acidic or basic conditions.
General reaction:
R—C≡N + H2O +ACID → R—CO—NH2
EXAMPLE:
CHз—C≡N + H2O + HCL
→ CHз—CO—NH2
17. CARBOXLYIC ACID WITH AMMONIA
IN this reaction , carboxylic acid containing different alkyl
groups react with ammonia to form different alkyl amides.
General Reactions:
R—CO—OH + NH3 → R—CO–NH2
Example
CH3–CH2–CO–OH + NH3 →CH3–CH2–CO–NH2 +
H2O
18. AMINES WITH CARBOXLYIC ACID
The reaction of carboxylic acid with amines to form
different alkyl amide.
General Reaction:
R–CO—OH +H2N—R → R—CO—NH—R
Example:
CHз—CO–OH + H2N—CHз →
CHз–CO–NH–CHз
19. AMINE WITH ANHYDRIDE
Amides with aldehydes
It is much more common however to prepare amides by
treating an amine with aldehyde.
General reaction:
R—CO—O—CO—R + R—NH—R ↔ R—CO—NR2 +
HO—CO—R
Example:
CHз–CO–O––CO–CHз + CHз–NH—CHз
↔CHз–CO–NH2 +HO–CO––CHз
20. CARBOXYLIC ACID WITH THIONYL
CHLORIDE
During the reaction the carboxylic acid is converted
to a chlorosulfite intermediate making it a better
leaving group.The chloride anion produced during
the reaction acts a nucleophile to produce acid
chloride and then react with amine(RNHR) to form
AMIDE.
Chemical Reaction:
R–CO–OH + SOCL2 →R–CO–CL
+RNHR→R–CO–NR–R (TERTIARY AMINE)
22. NITRILE FROM AMIDES
Amide are dehydrated by heating a solid mixture of
the amide and phosphorus oxide P4O10. Water is
removed from the amide group to leave a nitrile
group CN-CN . The liquid nitrile is collected by
simple distillation .
FOR EXAMPLE:
Ethane nitrile is formed by
dehydrating ethane amide.
CH3CONH2+P4O10→CH3CN+H2O
23. HOFFMANN’S REARANGEMENT:
The Hoffmann Re-arrangement is the organic reaction of a
primary amide to a primary amine with one fewer carbon
atom.
CHEMICAL REACTION:
RCONH2+Br2+NaOH→R-N=C=O
R-N=C=O+H2O→R-NH2+CO2
24. AMIDE REDUCTION
RCONR2 AMIDES are converted to amines
(RCH2NR’2)by conversion of the C═O to –CH2–.
Chemical Reaction :
LiALH4 + R–CO–NH2 → H–CHR–NH2
25. VILSMEIER –HAACK REACTION
SUBSTITUTION REACTION
It is a chemical reaction of a substituted amide with
phosphorous oxychloride and an electron –rich arene
to produce an aryl aldehyde or ketone.
The reaction is named after ANTON VILSMEIER and
ALBRECT HAACK.
27. BISCHLER –NAPIERALSKI REACTION
The BISCHLER-NAPIERALSKI REACTION is an
electrophilic aromatic substitution reaction that
allows for the cyclizatin of β-arylethylamides.
30. THERAPEUTIC USES OF AMIDES
AMIDES ARE IMPORTANT CLASS OF ORGANIC COMPOUNDS WHICH
HAVE MANY APPLICATIONS IN MEDICAL FIELD……
ACETAMIDE
It act as antidote when fluoroacetamide attacks on cardiac
muscles because this poison cause degeneration,necrosis of
cardiac muscles.Actamide is the only compound which reverse its
effects.
Actamalide tablet (250mg)is used to various serious disease;
EDEMEA
EPILEPSY
GLAUCOMA
31. BENZAMIDE
Its drugs are used to block DOPAMINE and SEROTONIN
receptors and stimulate acetylcholine receptors in smooth
muscles.
It is mainly used for vomiting and nausea.
Its derivative (procainamide) is used against life threatening
ventricular arrhythmias.
PROCAINAMIDE is used as anticancer drugs for the
treatmentof stage 3 and stage 4 hodgkin’s disease.
MOCLOBEMIDE is used for depression disorder and pipolar
disorder
SULPIRIDE is used to treat SCHIZOPHRENIA.
32. SULFONAMIDE (SULFA DRUGS)
They are used to treat bacterial infections.
They are prescribed for following disease;
Urinary tract infection
Bronchitis
Eye infections
Pneumonia
Ear infections
Severe burns
Traveller’s diarrhea
37. NOMENCLATURE
Amines are named in several ways ;
Typically , the compound is given the prefix
‘AMINO—’ or the suffix
‘AMINE’
LOWER AMINES ARE NAMED WITH SUFFIX ‘AMINE’.like methylamine
HIGHER AMINES HAVE PREFIX AMINO AS A FUNCTIONAL GROUP
IUPAC NAMING
Amines are written as “ALKANAMINE”
38. PHYSICAL PROPERTIES
Amines have characteristic ammonia smell ,liquid amines
have a distinctive fishy smell.
Aromatic amines such as aniline, have their lone pair
electrons conjugated into the benzene ring. Thus , their
tendency to engage in hydrogen bonding is diminished.
Aromatic boiling point are high but solubility in water is
low .
The water solubility of simple amines is enhanced by
hydrogen bonding involving these lone electron pairs.
39. The order of boiling point of amines is as follows :Primary > Secondary >
Tertiary.
The low aliphatic amines are gaseous in nature .
Primary amines with three or four carbon atoms are liquids at room
temperature whereas higher ones are solid.
Aniline and other arylamines are generally colorless . However , they get
colored when we stored them in open due to atmospheric oxidation.
Low aliphatic amines can form hydrogen bonds with water molecules.
Therefore , such amines are soluble in water.
Increase in the size of hydrophobic alkyl part increases the molar mass of
amines. This usually results in a decrease in its solubility in water.
40. Higher amines are insoluble in water. Organic solvents like alcohol ,
benzene and ether readily dissolves amines .
Alcohols have high polarity as compared to amines and hence , they form
stronger intermolecular bonds .
Primary and secondary amines are often engaged in the intermolecular
association as a result of hydrogen bonding between the nitrogen of one
and hydrogen of the other molecule .
The intermolecular associations is more prominent in case of primary
amines as compared to the secondary due to the availability of two
hydrogen atoms .
In tertiary amines , there is no intermolecular association due to the
absence of free hydrogen atom for bonding .
41. PREPERATION OF AMINES
PRIMARY AMINES
Hofmann's Degradation of Amides:
IN this reaction, primary amines are formed by this
method.so this reaction is used widely to that
purpose.
Chemical Reaction:
R—CO–NH2 + BR2 + 4NAOH → R–NH2 +2NABR
+NA2COз +2 H2O
42. GABRIEL PHTHALIMIDE METHOD
This r eaction is used to convert alkyl halides
into primary amines.
This reaction is named after German chemist
who first introduced it
43. SECONDARY AMINES PREPARATION
REDUCTION OF N –SUBSTITUTED AMIDES
Amides on reduction by lithium aluminium
hydride produce secondary amines
44. REDUCTION OF ISONITRILES
THIS REACTION IS VERY UNIQUE ONE.
Because in this reaction the secondary amine produced by it will always
have __CHз
CHEMICAL REACTION:
R___N+≡C- + PT. →
R___NH__CHз
45. TERTIARY AMINES
When an alcoholic ammonia solution is heated with an excess of alkyl
halide,a tri –alkyl ammonium halide is formed.This when heated
With sodium hydroxide solution gives free tertiary amine.
48. CHEMICAL PROPERTIES
CHEMICAL REACTIONS
Due to unshared paired electrons pair , amines can act both as bases and
as nucleophile
REACTION WITH ACIDS:
When react with acids,amine donate electrons
to form ammonium salts.
Chemical Reaction:
49. REACTION WITH ACID HALIDES
Acid halides reacts with amines to form
substituted amides.
Chemical Reaction:
55. DRUGS
Many drugs are designed to mimic or interfere with
natural amine neurotransmitter,exemplified by the
amine drugs;
Chlorpheniramine is an antihistamine that help to
cure allergic reactions due to cold ,hay fever,itchy
skin,insect bites, and stings.
Chlorpromazine is a tranquilizer that sedates
without inducing sleep.
It is used to relieve anxiety,excitement,
restlessness,and even mental disorders.
Ephedrine and phenylephrine,as amide
hydrochloride are used as decongestants.
57. Amphetamine,methamphetamine,and
methcathinone , are used
As physhostimulant amines.
Amitriptyline,imipramine,lofepramine,and
clomipramine are used as anti depressants
and are tricyclic amines.
Opiate analgesics such as heroin,
morphine,and codeine are also tertiary
amines.