Amines are organic compounds containing nitrogen that can be thought of as alkyl or aryl substituted

1
Amines are organic compounds containing nitrogen
that can be thought of as alkyl or aryl
substituted ammonia. Replace one H with CH3 to
get methylamine IUPAC methanamine. Replace
two Hs with CH3 to get dimethylamine IUPAC
N-methylmethanamine.
ammonia
2
Simple amines are commonly named as alkyl
substituted amines, with the substituents
alphabetized (some authors place the largest
group last)


ethylamine propylamine
1-methylbutylamine
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The IUPAC system is somewhat analogous to that
for alcohols i.e., drop the e from the longest
chain and add amine.


ethanamine propanamine pentan-2-amine Some
authors prefer to name amines as aminoalkanes.




aminoethane aminopropane 2-aminopentane
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Question Draw the condensed (or semi-condensed)
structures of Methylamine
dimethylamine triethylamine
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Question Draw the condensed (or semi-condensed)
structures of CH3NH2 Methylamine
dimethylamine
triethylamine
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Question Draw the condensed (or semi-condensed)
structures of CH3NH2 CH3NHCH3
Methylamine dimethylamine
triethylamine
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Question Draw the condensed (or semi-condensed)
structures of CH3NH2 CH3NHCH3
(CH3CH2)3N Methylamine
dimethylamine triethylamine
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Question Draw condensed (or semi-condensed)
structures of the following compounds and provide
the IUPAC names.

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Question Draw condensed (or semi-condensed)
structures of the following compounds and provide
the IUPAC names.
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Question Draw condensed (or semi-condensed)
structures of the following compounds and provide
the IUPAC names.
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Question What IUPAC rule of naming amines
accounts for the name N-propylbutan-1-amine
instead of N-butylpropan-1-amine for
CH3CH2CH2NHCH2CH2CH2CH3?
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Question What IUPAC rule of naming amines
accounts for the name N-propylbutan-1-amine
instead of N-butylpropan-1-amine for
CH3CH2CH2NHCH2CH2CH2CH3? Find the longest
chain with the amino group attached and name it
as the parent chain.
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IUPAC Name
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IUPAC Name N,3-dimethylbutan-2-amine
(you will also see N,3-dimethyl-2-butanamine)
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When NH2 appears as a substituent it is called
an amino group.
Question This is propanamide


How would one name this?
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When NH2 appears as a substituent it is called
an amino group.
Question This is propanamide
How would one name this?
3-aminopropanamide
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Question This is pentanoic acid
How would one name this?
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Question This is pentanoic acid
How would one name this?
4-aminopentanoic acid
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Question This molecule is commonly called
hexamethylenediamine or 1,6-diaminohexane.
Provide an IUPAC name.
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Question This molecule is commonly called
hexamethylenediamine or 1,6-diaminohexane.
Provide an IUPAC name.
Hexan-1,6-diamine (you will also see
1,6-hexanediamine)
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Ammonia is a base. Dissolving ammonia in water
results in the acid-base reaction
ammonia water
ammonium hydroxide The lone pair of
electrons on ammonia first hydrogen bonds with
water, and ultimately, steals a proton from
it. Amines hydrogen-bond with water and are
bases. (Isnt that how BrØnsted-Lowry acid/base
reactions must begin, hydrogen-bonding leading to
proton transfer?) Question Show how one water
molecule might hydrogen bond with two methylamine
molecules.
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Ammonia is a base. Dissolving ammonia in water
results in the acid-base reaction
ammonia water
ammonium hydroxide The lone pair of
electrons on ammonia first hydrogen bonds with
water, and ultimately, steals a proton from
it. Amines hydrogen-bond with water and are
bases. (Isnt that how BrØnsted-Lowry acid/base
reactions must begin, hydrogen-bonding leading to
proton transfer?) Question Show how one water
molecule might hydrogen bond with two methylamine
molecules.
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Question How might hydrogen bonding affect the
solubility of amines in water (amines with 5 or
fewer carbons)?
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Question How might hydrogen bonding affect the
solubility of amines in water (amines with 5 or
fewer carbons)?
Being able to form strong hydrogen bonds to water
will allow amines to dissolve in water, provided
the hydrocarbon portion of the amine is not too
large.
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Question Provide common names for the following
molecules and label them as primary (1?),
secondary (2?), or tertiary (3?) amines.
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Question Provide common names for the following
molecules and label them as primary (1?),
secondary (2?), or tertiary (3?) amines.
Hexylamine (primary)
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Question Provide common names for the following
molecules and label them as primary (1?),
secondary (2?), or tertiary (3?) amines.
Hexylamine (primary)
Dipropylamine (secondary)
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Question Provide common names for the following
molecules and label them as primary (1?),
secondary (2?), or tertiary (3?) amines.
Hexylamine (primary)
Dipropylamine (secondary)
Triethylamine (tertiary)
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Question Provide common names for the following
molecules and label them as primary (1?),
secondary (2?), or tertiary (3?) amines.
Hexylamine (primary)
Dipropylamine (secondary)
Triethylamine (tertiary)
Question Explain the trend in the boiling
points of the following isomers. Triethylamine,
bp 89?C dipropylamine, bp 110?C hexylamine, bp
132?C?
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Question Provide common names for the following
molecules and label them as primary (1?),
secondary (2?), or tertiary (3?) amines.
Hexylamine (primary)
Dipropylamine (secondary)
Triethylamine (tertiary)
Question Explain the trend in the boiling
points of the following isomers. Triethylamine,
bp 89?C dipropylamine, bp 110?C hexylamine, bp
132?C?
Hexylamine has two protons on nitrogen available
for hydrogen-bonding, and so has the highest
boiling point. Dipropylamine has one hydrogen
available. Triethylamine is not a hydrogen-bond
donor, and so boils more easily than the others.
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Question What can be concluded from the fact
that propylamine (IUPAC propan-1-amine) has a
boiling point of 48C, while propanol boils at
97C.
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Question What can be concluded from the fact
that propylamine (IUPAC propan-1-amine) has a
boiling point of 48C, while propanol boils at
97C.
Propanol (which could be called propan-1-ol) must
form stronger hydrogen bonds. Because oxygen is
more electronegative than nitrogen, the O-H bond
is more polarized than the N-H bond. Therefore,
the O-H hydrogen bears a stronger partial
positive charge. Having said this, we must
keep in mind the other side of hydrogen bonding,
namely, the ability of the nonbonding electron
pair to participate. In the case of nitrogen,
the nonbonding electrons are held less tightly,
so the lone pair is very good at establishing
H-bonds. In fact, it is this property that makes
amines good bases.
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Question Write an acid-base equation for the
reaction of tripropylamine with hydrogen
chloride.
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Question Write an acid-base equation for the
reaction of tripropylamine with hydrogen
chloride.
The conjugate acid of an amine is an ammonium
ion.
Question What is the name of the product formed
in the acid/base reaction above?
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Question Write an acid-base equation for the
reaction of tripropylamine with hydrogen
chloride.
The conjugate acid of an amine is an ammonium
ion.
Question What is the name of the product formed
in the acid/base reaction above?
Tripropylammonium chloride
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When studying phenols and carboxylic acids, we
drew resonance structures to show how the
negative charges present in the conjugate bases
are delocalized. Resonance delocalization has a
stabilizing effect on the conjugate base, which
increases the acidity of the proton. In
addition, because they are more stable, the
conjugate bases of phenols and carboxylic acids
are less basic than the conjugate bases of
alcohols. Question Amides are far less basic
than amines. Use resonance to show how the lone
pair of electrons on an amide nitrogen atom is
less available for use as a base.
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When studying phenols and carboxylic acids, we
drew resonance structures to show how the
negative charges present in the conjugate bases
are delocalized. Resonance delocalization has a
stabilizing effect on the conjugate base, which
increases the acidity of the proton. In
addition, because they are more stable, the
conjugate bases of phenols and carboxylic acids
are less basic than the conjugate bases of
alcohols. Question Amides are far less basic
than amines. Use resonance to show how the lone
pair of electrons on an amide nitrogen atom is
less available for use as a base.
38

• Many amines are physiologically active.
• Simple amines are irritating to the mucous
  membranes.
• Simple amines are toxic by ingestion or
  inhalation.
• Many amines affect the nervous system
• Some of the complex amines found in plants
  (alkaloids) are heterocycles.

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Question What is a heterocyclic compound?
Hint use the index of your textbook
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Question What is a heterocyclic compound?
Hint use the index of your textbook
A heterocyclic compound, or heterocycle, is a
cyclic compound that contains an atom other than
carbon in the ring.
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Imidazole and indole are two of many heterocyclic
nitrogen compounds which appear as components of
biologically important compounds.

The nitrogen atoms in these two compounds are
less basic than the nitrogen atoms in many other
heterocyclic nitrogen compounds, such as
pyrrolidine and piperidine.


Question What difference between the two groups
of heterocyclic compounds shown above might
account for this trend?

42
Imidazole and indole are two of many heterocyclic
nitrogen compounds which appear as components of
biologically important compounds.
The nitrogen atoms in these two compounds are
less basic than the nitrogen atoms in many other
heterocyclic nitrogen compounds, such as
pyrrolidine and piperidine.
Question What difference between the two groups
of heterocyclic compounds shown above might
account for this trend?
Short Answer The two compounds on the left are
aromatic. Aromatic molecules are less reactive.
Electron pairs on the aromatic ring are not as
basic.
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Question What difference between the two groups
of heterocyclic compounds shown above might
account for this trend?
Long Answer The two compounds on the left are
aromatic compounds they obey what is known as
the Hückel Rule, which states that cyclic
compounds are aromatic if they have 4n2 p
electrons (if n0, then 4n26). Both imidazole
and indole have 6 electrons in the p systems of
their rings. In these cases, the nitrogen atoms
have rehybridized to sp2, so that an extra pair
of electrons can join the fun.
Electron pairs that are a part of the aromatic p
system are unavailable for other actions they
are not basic. Other electron pairs on the ring
may act as bases, but the molecule as a whole is
more stable, and so they are less reactive than
nonbonding electron pairs on non-aromatic rings.
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Question Complete the reaction, using the most
basic amine group in the molecule

45
Question Complete the reaction, using the most
basic amine group in the molecule
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Question Alkaloids are naturally occurring
nitrogen-containing compounds obtained from
________ _________________. Question
Alkaloids are acidic / basic (circle one)
compounds. Question Alkaloids taste sour /
bitter (circle one) Many alkaloids are
poisons, but others, such as morphine, have
pharmacological value.
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Question Alkaloids are naturally occurring
nitrogen-containing compounds obtained from
________plants_________________. Question
Alkaloids are acidic / basic (circle one)
compounds. Question Alkaloids taste sour /
bitter (circle one) Many alkaloids are
poisons, but others, such as morphine, have
pharmacological value.
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Question Alkaloids are naturally occurring
nitrogen-containing compounds obtained from
________plants_________________. Question
Alkaloids are acidic / basic (circle one)
compounds. Question Alkaloids taste sour /
bitter (circle one) Many alkaloids are
poisons, but others, such as morphine, have
pharmacological value.
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Question Alkaloids are naturally occurring
nitrogen-containing compounds obtained from
________plants_________________. Question
Alkaloids are acidic / basic (circle one)
compounds. Question Alkaloids taste sour /
bitter (circle one) Many alkaloids are
poisons, but others, such as morphine, have
pharmacological value.
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Question Treating amines with _______
_______ converts amines into ammonium ions,
making them soluble in ____
____. Question In the stomach, amines are
ionic / neutral (circle one). Question To
enter the bloodstream from the gut, amines must
be in their charge neutral form. In what part of
the intestinal tract are amines absorbed?
Why?
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Question Treating amines with
_______acid________ converts amines into ammonium
ions, making them soluble in ____
____. Question In the stomach, amines are
ionic / neutral (circle one). Question To
enter the bloodstream from the gut, amines must
be in their charge neutral form. In what part of
the intestinal tract are amines absorbed?
Why?
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Question Treating amines with
_______acid________ converts amines into ammonium
ions, making them soluble in ____water____. Quest
ion In the stomach, amines are ionic /
neutral (circle one). Question To enter the
bloodstream from the gut, amines must be in their
charge neutral form. In what part of the
intestinal tract are amines absorbed?
Why?
53
Question Treating amines with
_______acid________ converts amines into ammonium
ions, making them soluble in ____water____. Quest
ion In the stomach, amines are ionic /
neutral (circle one). Question To enter the
bloodstream from the gut, amines must be in their
charge neutral form. In what part of the
intestinal tract are amines absorbed?
Why?
54
Question Treating amines with
_______acid________ converts amines into ammonium
ions, making them soluble in ____water____. Quest
ion In the stomach, amines are ionic /
neutral (circle one). Question To enter the
bloodstream from the gut, amines must be in their
charge neutral form. In what part of the
intestinal tract are amines absorbed? Why? The
stomach is highly acidic. As amines pass through
the stomach they pick up protons (if they havent
already), and are thereby present in their
conjugate acid (ammonium) form. As they move
into the small intestine, which is alkaline, the
ammonium ions lose their protons to the basic
media. Therefore, amines are in their neutral
(free base form) when they are in the alkaline
small intestine, where they are absorbed. They
must be neutral to pass through the nonpolar
membranes of the intestinal walls.
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Tributylammonium bromide is made water insoluble
by treatment with base.
Question Is tetrabutylammonium bromide made
water insoluble by treatment with base (OH-)?
Explain, using structures as needed.
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Tributylammonium bromide is made water insoluble
by treatment with base.
Question Is tetrabutylammonium bromide made
water insoluble by treatment with base (OH-)?
Explain, using structures as needed.
Not unless you beat the snot out of it with heat.
Under normal conditions a quaternary ammonium
ion will not react with hydroxide. The primary,
secondary and tertiary ammonium ions have a
proton to lose in an acid/base reaction. The
quaternary ammonium ion does not. If you insist
on cooking it, you can induce an elimination
reaction.
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Some Physiologically Active Amines
dopamine
serotonin
amphetamine
fluoxetine
diphenhydramine
caffeine
phenylephrine
histamine
tryptophan
nicotine
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epinephrine
psilocin
lysergic acid
histidine
?-aminobutyric acid (GABA)
glutamic acid
phenylalanine
3,4-methylenedioxy- methamphetamine (MDMA)
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• Assignment As a group, pick three
  physiologically active amines from
• the preceding list (substitutions may be made
  with instructor approval).
• You will give a 10 minute presentation which will
  include
• Chemical structures with all functional groups
  identified.
• A brief description of the function of each
  compound.
• Describe any relationships between the molecules.
  For instance
• How are the structures similar?
• Are the functions similar?
• Do they act on the same physiological systems?
• Do they share a common synthetic pathway?
• You may use PowerPoint, transparencies, or other
  suitable graphical
• representations.
• Part of your grade will be based on peer
  evaluation.

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Grading Rubric for CHEM 124 Introduction to
Organic and Biochemistry Group name
_____________________________________
Topic _____________________________________ Group
members