Transcript Chapter 16 Notes

Chapter 16:
Amines and Amides
1
AMINES
• Amines are derivatives of ammonia, NH3, where one or
more hydrogen atoms have been replaced by an organic
(R) group.
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COMMON NAMING FOR AMINES
• Alphabetically link the names of the alkyl or aromatic
groups bonded to the nitrogen and attach the suffix
–amine so the name is one word.
• Use di- or tri- prefixes for identical alkyl groups.
Examples:
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IUPAC NAMING FOR PRIMARY AMINES
• The –NH2 group is treated as a chain substituent called the
amino group.
Examples:
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IUPAC NAMING FOR AMINES
• Name the longest chain attached to the nitrogen.
• Replace the final –e with –amine.
• Number the chain so the carbon bonded to the nitrogen
has the lowest possible number.
• Number the other substituents on the carbon chain.
• An italic “N” is used as a prefix for a substituent on
nitrogen.
Examples:
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NAMING AROMATIC AMINES
• Aniline is the simplest aromatic amine.
• Compounds are named as substituted anilines.
• An italic “N” is used to indicate that an alkyl group is
attached to the nitrogen and not to the ring.
Examples:
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Coached Problem
6
PHYSICAL PROPERTIES OF AMINES
• The N-H bond is not quite as polar as the O-H bond.
• Primary and secondary amines can form hydrogen bonds
between molecules.
• The hydrogen bonds are not as strong as those of
alcohols, so amine boiling points are somewhat lower than
those of alcohols.
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PHYSICAL PROPERTIES OF AMINES, cont.
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Coached Problem
8
PHYSICAL PROPERTIES, cont.
• Amines can hydrogen bond with water, making smaller
amine molecules usually water soluble.
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Chemistry Interactive
9
AMINE REACTIONS
• All amines behave as weak bases in water (similar to
ammonia)
R-NH2 + H2O  R-NH3+ + OH-
Examples:
CH3-NH-CH2CH3 + H2O  CH3-NH2-CH2CH3+ + OHmethylethylamine
methylethylammonium ion
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AMINE REACTIONS, cont.
• All amines behave as weak bases and form salts when
they react with acids such as HCl.
R-NH2 + HCl  R-NH3+Clamine
acid
amine salt
Example:
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AMINE SALTS
• Name by changing “amine” to “ammonium” and adding the
anion name.
• More water soluble than parent amine, a useful
characteristic for administering amine drugs
• Can be converted back to amine form:
• Quaternary ammonium salts have four alkyl groups
attached to the nitrogen.
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AMIDE FORMATION
• Amines react with acid chlorides or acid anhydrides to form
amides.
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AMIDE FORMATION, cont.
• Primary and secondary amines can form amides.
• Tertiary amines do not react to form amides.
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Examples:
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Coached Problem
15
POLYAMIDE FORMATION
• Reaction of diacid chlorides with diamines produces
polyamides that, like polyesters, are condensation
polymers.
• The repeating units in polyamides are held together by
amide linkages.
• 3 billion pounds of nylon and related polyamides produced
annually
• Proteins are polyamides ( e.g. silk and wool)
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Chemistry Interactive
16
AMINE NEUROTRANSMITTERS
• Neurotransmitter – a chemical bridge between nerve cells
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IMPORTANT AMINE NEUROTRANSMITTERS
• Acetylcholine
• Dopamine – synthesized from the amino acid tyrosine
• Norepinephrine – synthesized from dopamine, may be
associated with mental illness
• Serotonin – synthesized from the amino acid tryptophan,
may be associated with mental illness
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OTHER BIOLOGICALLY IMPORTANT AMINES
• Epinephrine (adrenaline) – more important as a hormone
than a neurotransmitter
• Fight-or-flight hormone, released in response to pain,
anger, or fear, increases blood glucose level for energy
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OTHER BIOLOGICALLY IMPORTANT AMINES, cont.
• Amphetamines – nervous system stimulants, similar in
structure to epinephrine
• Abuse of amphetamines has severe detrimental effects on
the body and the mind
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OTHER BIOLOGICALLY IMPORTANT AMINES
• Alkaloids – a class of nitrogen-containing organic
compounds obtained from plants.
Examples include:
• Nicotine – found in tobacco
• Caffeine – found in coffee and cola drinks
• Quinine – used to treat malaria
• Opium – used to make codeine (in cough medicines),
morphine (pain killer), and heroin
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NAMING AMIDES
• Use the carboxylic acid’s name and drop the –ic ending
(common name) or –oic ending (IUPAC name) and change
to –amide.
Examples:
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NAMING AMIDES
• Use N to denote alkyl groups attached to the nitrogen
atom.
Examples:
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PHYSICAL PROPERTIES OF AMIDES
• Hydrogen bonding between unsubstituted amides causes
them to have high melting points.
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PHYSICAL PROPERTIES, cont.
• Amides can form hydrogen bonds with water, making
smaller amide molecules rather water soluble.
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AMIDE REACTIONS
• Amides are neither acidic nor basic.
• Hydrolysis – the reverse of amide formation, an amide is
cleaved to produce a carboxylic acid and an amine or
ammonia
• Amide hydrolysis is a central reaction in the digestion of
proteins and the breakdown of proteins within cells.
• In the body, this hydrolysis is catalyzed by enzymes.
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AMIDE REACTIONS – HYDROLYSIS, cont.
• The products of an amide hydrolysis depend on whether
the reaction occurs in acidic or basic conditions.
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Specific Examples:
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Coached Problem
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