13B CH110 Amines

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Chapter 13B Amines and Amides

13.4

Amines

Copyright © 2007 by Pearson Education, Inc.

Publishing as Benjamin Cummings

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Amines

Amines

Are derivatives of ammonia NH3.

Contain N attached to one or more alkyl or aromatic

groups.

CH3 CH3

CH3—NH2 CH3—NH CH3—N—CH3

NH2

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Classification of Amines

Amines are classified as primary, secondary, or tertiary.

In a primary (1°) amine, one carbon group is bonded

to the nitrogen atom.

A secondary (2°) amine has two carbon groups. A tertiary (3°) amine has three carbon groups.

H CH3 CH3

| | |

CH3—N—H CH3—N—H CH3—N—CH3 1° 2° 3°

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Models of Amines

The three-dimensional models show the shapes of amine molecules with one or more alkyl groupsbonded to the nitrogen atom.



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Simple amines

Are named as alkylamines.

List the names of the alkyl groups bonded to the N

atom in alphabetical order in front of amine.

CH3—CH2—NH2 ethylamine

CH3—NH—CH3 dimethylamine

CH3

|

CH3—N—CH2—CH3 ethyldimethylamine

Naming Amines: Common

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In the IUPAC system,

Amines are named as alkanamines.

The e in the alkane name of the longest chain is

changed to amine.

The chain is numbered to locate the amine group

and substituents.

NH2

|CH3—CH2—NH2 CH3—CH—CH3

Ethanamine 2-Propanamine

Naming Amines: IUPAC

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Number longest alkane chain

Naming Amines: IUPAC

N -Methyl-1-propanamine

N -Methyl-2-butanamine

2o or 3o amines

HN—

CH3 |

CH3—CH—CH2—CH3

3 2 1

1 2 3 4

CH3—

CH2—

CH2—

NH—

CH3

Alkyl grps bonded to N are named as N-alkyl grp

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Give the common and IUPAC names, and classify as

primary, secondary, or tertiary:

A. CH3—CH2—CH2—NH2

CH3

|

B. CH3—CH2—N—CH3

Learning Check

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Give the common and IUPAC names, and classify as

primary, secondary, or tertiary:

A. CH3—CH2—CH2—NH2

CH3

|

B. CH3—CH2—N—CH3

n-propylamine, 1-propanamine, 1°

ethyldimethylamine,

N,N- dimethylethanamine, 3°

Solution

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Write a structural formula for

A. 2-pentanamine

B. N -methyl-1-butanamine

Learning Check

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A. 2-pentanamineNH2 |

CH3—

CH—

CH2—

CH2—

CH3

B. N -methyl-1-butanamine

CH3—CH2—CH2—CH2—NH—CH3

Solution

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Aromatic Amines

The amine of benzene is aniline.

Alkyl groups on the N use the prefix N- and the alkyl

name.

Aniline 3-chloroaniline N-methylaniline

NH2

Cl

NH2 CH3NH

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Learning Check

Give a name for each:

A. CH3—NH—CH2—CH3

CH3

|

B. CH3—CH2—N—CH2—CH2—CH2—CH3

C.NH

2

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Solution

A. CH3—NH—CH2—CH3

ethylmethylamine; N -methylethanamine

CH3

|

B. CH3—CH2—N—CH2—CH2—CH2—CH3

N-ethyl-N -methyl-1-butanamine

C. anilineNH2

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Boiling Points:

of similar mass.

Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

Alcohols > Amines >Alkanes

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Hydrogen Bonding for Amines

The polar N-H bond

Provides hydrogen bonding in 1°and 2° amines, but not 3°.

In amines is not as polar as the O-H bonds in alcohols.


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Solubility in Water

Amines are soluble in water

If they have 1-5 carbon atoms.

Because the N atom in smaller amines forms

hydrogen bonds with the polar O-H bond in water.

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Learning Check

Consider the following compounds:

1. CH3—CH2—CH2—NH2

2. CH3—CH2—NH—CH3

3. CH3—CH2—CH2—CH3

A. Which compound has the highest boiling point?

B. Which compound(s) is(are) soluble in water?

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Solution

Consider the following compounds:



3. CH3—CH2—CH2—CH3

A. Which compound has the highest boiling point?


B. Which compound(s) is(are) soluble in water?



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Amines are

Bronsted-Lowry bases that attract a H+ from H2O

to the N atom.

Weak bases in water.

NH3 + H2O NH4+ + OH –

ammonium hydroxide

CH3—NH2 + H2O CH3—NH3+ + OH –

methylammonium hydroxide

Amines React as Bases

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An amine salt

Forms when an amine is

neutralized by acid.

Is named by replacing the amine

part of the name with ammonium

followed by the name of the

negative ion.

CH3—NH2 + HCl CH3—NH3+Cl –

methylamine methylammonium

chloride

Neutralization forms Amine Salts

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Properties of Amine Salts

Amine salts are

Solids at room temperature.

Soluble in water and body fluids.

The form used for drugs.


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Cocaine

Cocaine

Is sold illegally as an amine salt.

Is reacted with NaOH to produce the free amine form

known as ―crack‖.


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Learning Check

Write the equation for ethylamine when it reacts with

each of the following:

1. + H2O

2. + HCl

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Solution

Write the equation for ethylamine when it reacts with

each of the following:

1. CH3—CH2—NH2 + H2O CH3—CH2—NH3+

OH –

2. CH3—CH2—NH2 + HCl CH3—CH2—NH3+ Cl –

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Heterocyclic Amines

A heterocyclic amine

Is a cyclic organic compound.

Has a five- or six-atom ring.

Contains one or more nitrogen atoms.

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Examples of Heterocyclic Amines



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Learning Check

Identify the following heterocyclic amines:

1. 2. 3.

N

H

N

H

N

H

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Solution

Identify the following heterocyclic amines:

1. 2. 3.

1. piperidine 2. pyrrole 3. imidazole

N

H

N

H

N

H

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Alkaloids are

Physiologically active nitrogen-containing

compounds.

Produced by plants.

Used as stimulants, anesthetics, and

antidepressants.

Often habit forming.

Alkaloids

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Nicotine

Nicotine

Increases the adrenaline level in the blood.

Causes addiction to tobacco.

Contains a pyrrolidine ring.

NCH3

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Alkaloids Related to Morphine

Alkaloids Such as morphine and codeine are produced by the poppy.

Have been used for centuries as painkillers.

Such as heroin and codeine are modifications of morphine.

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Morphine and Codeine

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Pharmacology

An area of research in pharmacology

Is to design drugs such as procaine, lidocaine, and

demerol that retain some of the characteristics of

alkaloids.

Is to modify the structures of cocaine and morphine to

produce anesthesia, but without the addictive side

effects.

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Pharmacology

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Learning Check

Identify the heterocyclic amine in serotonin.

serotonin

HO

N

H

CH2 CH2 NH2

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Solution

Identify the heterocyclic amine in serotonin.

pyrrole

N

HO

CH2

H

CH2 NH2

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Amides

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In amides, an amino group( –NH2) replaces the –OHgroup of carboxylic acids.

O O

|| ||

CH3—C—OH CH3—C—NH2

Amides

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Amides are named as alkanamides.

IUPAC replaces –oic acid ending with –amide.

Common names replace -ic acid ending with –amide.

O Methanamide (IUPAC)

H—C—NH2 Formamide (common)

O Propanamide (IUPAC)

CH3—CH2—C—NH2 Propionamide (common)

Naming Amides

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An alkyl group bonded to the N atom is named as

N -alkyl in front of the amide name.

O H

│CH3 —C—N—CH3 N -methylethanamide (IUPAC)

N -methylacetamide (common)

O H

│

CH3—CH2 —C—N—CH2—CH3 N -ethylpropanamide (IUPAC)

N -ethylpropionamide (common)

Naming Amides with N Groups

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Aromatic Amides

The amide of benzene is named benzamide.

C

O

NH2

Benzamide

C

O

NH CH3

N methylbenzamide-

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Solution

O

A. CH3 –CH2 –CH2 –C –NH2

butanamide; butryamide

O H

│

B. CH3 –C –N –CH2 –CH3

N-ethylethanamide; N-ethylacetamide

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Solution

A. pentanamide

O

CH

3

–CH2

–CH2

–CH2

–C –NH2

B. N -methylbutyramide

O

CH3 –CH2 –CH2 –C –NH –CH3

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Classification of Amides

Amides are classified according to the number of

carbon atoms bonded to the nitrogen atom.O H|| |

CH3—C—N—H Primary (1°) amide

O H|| |

CH3—C—N—CH3 Secondary (2°) amide

O CH3 || |

CH3 —C—N—CH3 Tertiary (3°) amide

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Give the common and IUPAC names for the following

amides and classify as primary, secondary, or tertiary:

O

|| A. CH3—CH2—CH2—C—NH2

O CH3 || |B. CH3—C—N—CH2—CH3

Learning Check

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O||

A. CH3—CH2—CH2—C—NH2

butryamide (common);butanamide (IUPAC) primary(1°) amide

O CH3 || |

B. CH3—C—N—CH2—CH3

N-ethyl-N-methylacetamide (common);

N-ethyl-N-methylethanamide (IUPAC)

tertiary (3°) amide

Solution

S A id i H lth d

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Some Amides in Health and

Medicine

Urea is the end product of protein metabolism.

Saccharin is an artificial sweetener.

Some amides such as phenobarbital, Nembutal

and Seconal are barbiturates. Acetaminophen is used to reduce fever and

pain.

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Some Amides in Health and Medicine


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Physical Properties of Amides

Amides

That are primary (−NH2) or secondary (−NH−) form

hydrogen bonds.

That are primary have higher melting points than

secondary.

That are tertiary (no H on N) do not form hydrogen

bonds and have lower melting points.

All form hydrogen bonds with water.

With 1-5 carbon atoms are soluble in water.

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Hydrolysis of Amides

Amides undergo

acid hydrolysis base hydrolysis

carboxylic acid salt of carboxylic acid

ammonium salt and an amine or ammonia

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Write the equation for the hydrolysis of

N-ethylpropanamide with NaOH.

Learning Check

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Write the products of the hydrolysis of

N-ethylpropanamide with NaOH.

O

CH3—CH2—C—N—CH2—CH3 + NaOH

N -ethylpropanamide

O

CH3—CH2—C—O – Na+ + CH3—CH2—NH2

Solution

13B CH110 Amines

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