Bonding Characteristics of
Nitrogen
• Nitrogen is a member of Group VA of the periodic table
• Nitrogen has five valence electrons
• Nitrogen can form three covalent bonds to complete its octet of electrons
C N O
4 Valence electrons 4 Covalent bonds
No nonbonding electron pairs
5 Valence electrons 3 Covalent bonds
1 No nonbonding electron pairs
6 Valence electrons 2 Covalent bonds
Structure and Classification of
Amines
NH3 CH3—NH2 (CH3)2NH (CH3)3N
0 Amine: Organic derivative of ammonia (NH3) in which one or more
alkyl, cycloalkyl, or aryl groups are attached to the nitrogen atom
Cyclic Amines
0 Cyclic amines either secondary or tertiary amines
0 Cyclic amines are designated as heterocyclic compounds 0 Numerous heterocyclic amines are found in biochemical
systems
O N
N
N N
O
N
N
Nomenclature of Amines
0 Select as the parent carbon chain the longest chain to which
the nitrogen atom is attached.
0 Replace the –e ending of the alkane chain with –amine.
0 Number the parent chain to give the carbon bearing the amine
group the lowest possible number.
0 Name and number all substituents, and add them as prefixes to
the “alkanamine” name.
NH2
Nomenclature of Amines
0 For secondary or tertiary amines the prefix N-alkyl is added to
the name of the parent compound.
0 The amine of benzene is given the name aniline (benzenamine) 0 If additional groups are attached to the nitrogen of an aromatic
amine, they are indicated with the letter N- followed by the name of the group.
Carboxylic acid
Aldehyde Increasing
Ketone Priority
Alcohol Amine
N-methyl-1-hexanamine
H2N NH2
4-bromoaniline
Common Names of Amines
0 The alkyl groups bonded to the nitrogen atom are listed in
alphabetical order.
0 The prefixes di and tri are used to indicate two and three
identical substituents.
N H
N
Physical Properties
0 Ammonia or fishy odors. 0 Irritating to skin and eyes.
0 Boiling points lower than alcohols because N-H hydrogen bonds are weaker than O-H hydrogen bonds.
Except for
Solubility
0 Amines with fewer than six carbon atoms are infinitely soluble
in water.
0 Solubility results from hydrogen bonding between the amines
and water.
0 Even tertiary amines are water-soluble because of its ability to
Basicity of Amines
0 Amines behave like NH3 and are basic: This behavior is due to
the acceptance of H+ (proton) from an acid.
0 The resulting solution is alkaline due to OH- ion and a substituted ammonium
ion.
0 Ammonium and substituted ammonium ions form four bonds with N ;
therefore carries a + charge
0 Names of substituted ammonium ions are derived from the parent
amine in which the “-e” of parent amine is replaced by “ammonium ion”.
H2N
2-Propanamine
+ H OH H3N
-Amine Salts
0 The reaction between an acid and a base (neutralization)
results in a salt
0 Amines are bases and their reaction with an acid produces a
salt (amine salt)
0 Names of amines salts are written in the following order:
0 Substituted amine followed by the name of anion
0 Putting vinegar (acid) on fish to remove odor
0 Results in the formation of an odorless amine salts
0 All amine salts are water soluble
0 This is why drugs of amines are administered in the form of
Important Amines: Neurotransmitters
O N+
O
acetylcholine
HO
OH H2N
Copyright © 2001 Houghton Mifflin Company. All rights reserved.
Chemistry at a Glance
Summary of
reactions
Practice: Amine Reactions
0 Write the formula for the reaction
2-butanamine + HCl → ?
Important Amines
0 Epinephrine:
0 Important in central nervous system stimulant
0 Released into blood in response to pain, excitement and fear. 0 Increases rate and force of heart contraction and muscular
strength
0 Histamine:
0 Responsible for unpleasant effects during hay fever and pollen
allergies
0 Antihistamine is used to counter the effects of histamine
HO
OH
NH HO
epinephrine
H2N
NH
N
Important Amines
0 Dopamine: Neurotransmitter found in the brain,
deficient in Parkinson’s patients
0 Administered as L-dopa because dopamine cannot cross
the blood-brain barrier
0 Serotonin: a brain chemical involved in sleep, sensory
Alkaloids
0 Alkaloid: An alkaloid is a nitrogen-containing
organic compounds excreted from plant material
0 Well known alkaloids:
0 Nicotine (tobacco plant)
0 Caffeine (coffee beans and tea leaves)
0 Theobromine (cocoa beans)
0 Cocaine (coca plant)
0 Morphine and codeine (Opium plant)
Amides
Amides: Derivatives of carboxylic acids in which the “-OH”
group of the carboxylic acid is replaced by an NH2 or NHR or NR2
C
C H2 H3C
O N H H C C H2 H3C
O
N CH3
H
C
C H2 H3C
O
N CH3
CH3
1° amide 2° amide 3° amide
C H
O
N H
Copyright © 2001 Houghton Mifflin Company. All rights reserved.
Chemistry at a Glance
Summary of
reactions
Amide Formation
Amidification/Amidation = Condensation Reaction
O
OH
+ N H
H
H O
NH2
+ H2O Heat
O
OH
+ N CH3
H
H O
N H
Nomenclature of Amides
0 The ending of the name of the carboxylic acid is changed from
“-ic” acid (common) or “-oic” acid (IUPAC) to -amide
Example: benzoic acid becomes benzamide
0 The names of groups attached to the nitrogen (2º and 3º
amides) are appended to the front of the base name, using an N- prefix as a locator
O
NH2
4-methylpentanamide
O
N
Selected Amides:
Urea
0 Naturally occurring amide, water-soluble white solid produced
in the human body from carbon dioxide and ammonia through urea cycle
Human nitrogen waste product
0 Kidneys remove it from blood and we excrete it via urine
0 Kidneys not functioning properly leads to urea accumulation in
blood - Uremia
C O O + N H H H N H H H C O NH2
Selected Amides:
Melatonin
0 A polyfunctional amide
0 A hormone (synthesized by the pineal gland) that
regulates the sleep–wake cycle in humans.
H N
O
H N
Selected Amides:
Acetaminophen
0 Synthetic amides exhibit physiological activity and are used as
drugs.
0 Foremost among them is acetaminophen,
0 The top-selling over-the-counter pain reliever 0 Acetaminophen is a derivative of acetamide
N H O
OH
O
Selected Amides:
Barbituates
0 Cyclic amides- derivatives of barbituric acid 0 First synthesized from urea and malonic acid 0 Heavily used group of prescription drugs
0 Cause relaxation (tranquilizers), sleep (sedatives), and
death in case of overdoses O
N
Physical Properties
0 Amides do not exhibit basic properties in solution like amines because:
0 Electrons not available for bonding to H+ ions
0 Electrons are pulled by more electronegative atom in the carbonyl
group.
0 Boiling points of amides:
0 Monosubstituted > Disubstituted > Trisubstituted
0 Monosubstituted amides are solids except for formamide 0 Formamide exhibits hydrogen bonding
Copyright © 2001 Houghton Mifflin Company. All rights reserved.
Chemistry at a Glance
Summary of
reactions
Chemical Reactions:
Acid
Hydrolysis
0 As in the case of esters, amides under go hydrolysis to release
free acid and an amine
0 Amide hydrolysis is catalyzed by:
0 Acids and bases, or certain enzymes
0 Sustained heating may be needed in certain cases
C O
+ HOH + HCl C
O
OH
H3C + NH4 Cl
Chemical Reactions:
Base
Hydrolysis
(
Saponification
)
+ NaOH O
NH
Na+ O
O
Polyamides
0 Amide polymers or polyamides: Synthesized by combining
diamines and dicarboxylic acids in a condensation polymerization reaction.
0 Nylon is a synthetic polyamide
0 Many different types of Nylons
0 Based on diamine and diacid monomers used
0 Nylon 66 – a polymer of 1,6-hexanediamine and hexanedioic
acid as monomers NH2
H2N
O
OH
Nylon Polymer
Practice: Amide Reactions
N-ethylpropanamide + HCl + HOH → ?
