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Chemistry B11. Chapter 16,17 & 18 Amines, Aldehydes, Ketones and Carboxylic Acids. Amines. Amines. Amines: Are derivatives of ammonia NH 3 . Contain N attached to one or more alkyl (Aliphatic amine) or aromatic groups (Aromatic amine). CH 3 - NH 2 CH 3 - NH - CH 3. -NH 2 amino group.

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slide1

Chemistry B11

Chapter 16,17 & 18

Amines, Aldehydes, Ketones

and Carboxylic Acids

slide3

Amines

  • Amines:
  • Are derivatives of ammonia NH3.
  • Contain N attached to one or more alkyl (Aliphatic amine) or aromatic groups (Aromatic amine).
  • CH3-NH2CH3-NH-CH3

-NH2 amino group

NH2

slide4

Amines

Amines are classified into three groups:

depending on the number of carbon groups bonded to nitrogen.

CH3 CH3

 

CH3—NH2 CH3—NH CH3—N—CH3

Tertiary 3°

Secondary 2°

Primary 1°

slide5

NH2

NH2

CH3-CH-CH3

CH3-CH-CH-CH3

Cl

Naming Amines

IUPAC name – 1° amines

  • The same method as we did for alcohols.
  • - Drop the final “-e” of the parent alkane and replace it by “-amine”.
  • - Use a number to locate the amino group (-NH2) on the parent chain.

3

1

5

3

2

4

6

1

2

4

3

1

2

2-propanamine

3-chloro-2-butanamine

1,6-hexanediamine

slide6

Naming Amines

Common name

Names of alkyl groups (In alphabetical order) + “amine”

CH3—CH2—NH2 ethylamine

CH3—NH —CH3 dimethylamine

CH3

|

CH3—N—CH2—CH3 ethyldimethylamine

slide7

Aniline (common name)

NH2

Aniline

NH2

NH2

NH2

2

2

1

1

2

1

CH3

3

3

3

4

CH3

4

Cl

NO2

3-Methylaniline

4-Nitroaniline

4-Chloro-3-methylaniline

slide8

CH3

CH3-N-CH2-CH3

aniline

Naming Amines

IUPAC name – 2° and 3° amines

  • Take the largest group bonded to nitrogen as the parent amine.
  • Name the smaller group(s) bonded to nitrogen, and show their locations on nitrogen by using the prefix “N”.

N,N-Dimethylethanamine

slide9

N

CH3

H

H

Heterocyclic amines

When N is one of the atoms of a ring.

Pyrrolidine

Pyridine

Nicotine

slide10

Physical properties of Amines

  • They have unpleasant odors (rotting fish like ammonia).
  • They are polar compounds.
  • Difference in electronegativity between N - H (3.0 – 2.1 = 0.9)
  • 3. 1° and 2° amines have hydrogen bonds (N-H).
  • Weaker than alcohols (O-H).
  • 3° amines do not form hydrogen bonds (no H atom).
  • Boiling points: Hydrocarbons< Amines < Alcohols
  • Almost soluble in water (hydrogen bonding).
slide11

H

H

.

.

.

.

-

.

.

.

.

+

.

.

.

.

CH3

+

CH3

N

N

H

H – O – H

O – H

H

H

Chemical properties of Amines

They are weak bases (like ammonia): react with acids.

(to form water-soluble salts)

Some amines present in our blood and make it approximately basic (pH = 7.4).

slide12

Chemical properties of Amines

Aliphatic amines are weak bases by comparison with inorganic bases

such as NaOH, they are strong bases among organic compounds.

Aliphatic amines are stronger bases than aromatic amines.

(slightly stronger than NH3)

slide13

Examples

  • Complete each acid-base reaction and name the salt formed.
slide14

Examples

  • Complete each acid-base reaction and name the salt formed.

Solutions:

slide15

Aldehydes

Ketones

slide16

O

=

C

Carbonyl group

Aldehydes

Ketones

Carboxylic acids

Esters

slide17

Aldehydes and Ketones

O

=

C

  • In an aldehyde, at least one H atom is attached to a carbonyl group.
  • In a ketone, two carbon groups are attached to a carbonyl group.
slide18

Naming Aldehydes

Step 1

Select the longest carbon chain

that contains the carbonyl group (C=O).

Step 2

Number from the end nearest C=O group.

Step 3

Change the ending of parent alkane from -e to -al.

No number for carbonyl group C=O (it always comes first).

Step 4

Give the location and name of each substituent

(alphabetical order) as a prefix to the name of the

main chain.

slide19

Naming Aldehydes

  • Common names for the first two aldehydes use the prefixes “form” (1C) and “acet” (2C)followed by “aldehyde”.
  • OOO
  • ║ ║ ║
  • H─C─H CH3─ C ─H CH3─CH2─ C ─H
  • methanal ethanal propanal
  • (formaldehyde) (acetaldehyde)
slide20

O

  • CH3─CH─CH2─ C─H 3-Methylbutanal
  • O
  • Cl─CH2─CH2─ C─H 3-chloropropanal

CH3

4

3

2

1

3

2

1

slide21

Naming Ketones

Step 1

Select the longest carbon chain

that contains the carbonyl group (C=O).

Step 2

Number from the end nearest C=O group.

Step 3

Change the ending of parent alkane from -e to -one.

Use the number to show the location of C=O.

Step 4

Give the location and name of each substituent

(alphabetical order) as a prefix to the name of the

main chain.

slide22

Naming Ketones

  • In the common name, name the “alkyl groups” alphabetically attached to the carbonyl group and add the word “ketone”.
  • OO
  • ║ ║
  • CH3 ─ C ─CH3 CH3─C─CH2─CH3
  • propanone 2-butanone
  • (dimethyl ketone) (ethyl methyl ketone)

2

1

3

4

slide25

δ-

δ+

δ-

δ+

Physical properties of Aldehydes and Ketones

  • They have strong odors (ketones have pleasant odors).
  • They are polar compounds.
  • Only dipole-dipole interactions (no hydrogen bonding).
  • Low boiling points compare to amines and alcohols.
  • Soluble in water (no soluble in nonpolar compounds).

C-O 3.5-2.5 = 1

Higher than hydrocarbons.

H

O

δ+

H

Hydrogen bond with water.

slide26

O

=

CH3─CH2─CH2─CH2─C─H

Pentanal

Liquid aldehydes

are sensetive to oxidation.

No oxidizing agent

Chemical properties of Aldehydes and Ketones

1. Oxidation: only for aldehydes (not for ketones).

O

K2Cr2O7

=

CH3─CH2─CH2─CH2─C─OH

H2SO4

Pentanoic acid

K2Cr2O7: Oxidizing agent

slide27

t

r

a

n

s

i

t

i

o

n

m

e

t

a

l

c

a

t

a

l

y

s

t

H

2

1

-

P

e

n

t

a

n

o

l

t

r

a

n

s

i

t

i

o

n

O

OH

m

e

t

a

l

c

a

t

a

l

y

s

t

=

-

H

+

CH3─CH─CH2─CH3

CH3─C─CH2─CH3

2

2-butanol

2-butanone

Chemical properties of Aldehydes and Ketones

2. Reduction:

  • Like reducing the alkene (C = C) to alkane (C – C):
    • Reduction of an aldehyde gives a primary alcohol (-CH2OH).
    • Reduction of a ketone gives a secondary alcohol (-CHOH-).

O

=

+

CH3─CH2─CH2─CH2─C─ H

CH3─CH2─CH2─CH2─CH2─ OH

Pentanal

slide28

Chemical properties of Aldehydes and Ketones

NaBH4

Sodium borohydride: produces hydride ion: H-

Reducing agent

Reduction mechanism:

-

slide30

Carboxylic Acids

A carboxylic acid contains a carboxyl group, which is a carbonyl group attach to a hydroxyl group.

carbonyl

group

O



CH3 —C—OHhydroxyl group or CH3COOH

carboxyl group

CH3CO2H

slide31

Naming Carboxylic Acids

  • In the IUPAC name of carboxylic acids, the “-e” in the name of the longest chain is replaced by “-oic acid”.
  • The common names use prefixes “form-” and “acet-” for the first two carboxylic acids.
  • H-COOH methanoic acid formic acid
  • CH3-COOH ethanoic acid acetic acid
  • CH3-CH2-COOH propanoic acid
  • CH3-CH2-CH2-COOH butanoic acid
slide32

O

H

H

N

C

O

O

H

2

O

H

Naming Carboxylic Acids

  • Number the chain beginning with the carbon of the carboxyl group.
  • Because the carboxyl carbon is understood to be carbon 1, there is no need to give it a number.

CH3

CH2 – CH3

1

3

1

2

CH3─CH─CH2─COOH

CH3─CH2─CH─COOH

2-Ethylbutanoic acid

3-Methylbutanoic acid

O

4

1

5

1

5-Hydroxylhexanoic acid

4-Aminobenzoic acid

slide33

H

O

O

H

H

O

O

H

H

O

H

O

H

O

O

H

O

H

O

H

Naming Dicarboxylic Acids

  • Add the suffix “-dioic acid” to the name of the parent alkane that contains both carboxyl groups; thus, “-ane”becomes “-anedioic acid”.
  • The numbers of the carboxyl carbons are not indicated because they can be only at the ends of the chain.

O

O

O

1

3

1

2

O

Ehanedioic acid

Propanedioic acid

O

O

O

O

5

1

1

1

6

4

O

O

Butanedioic acid

Pentanedioic acid

Hexanedioic acid

slide34

Hydrogen bonding

between two molecules

d

-

d

+

O

H

O

C

C

H

H

C

C

3

3

O

O

H

d

+

d

-

Physical properties of Carboxylic Acids

  • 1- The carboxyl group contains three polar covalent bonds;
  • C=O, C-O, and O-H. So they are so polar.
  • 2-Carboxylic acids have higher boiling points than other types of organic compounds (with the same molecular weight) because of hydrogen bonding.
  • 3- They are more soluble in water than alcohols, ethers, aldehydes, and ketones because of stronger hydrogen bonding.
  • 4- Liquid carboxylic acids have sharp and disagreeable odors.
  • 5- They taste sour (exist in pickle, lime, and lemon).
slide35

Fatty Acids

  • Long, unbranched chain carboxylic acids and they are found in animal fats, vegetable oils, or phospholipids of biological membranes.
  • Most have between 12 and 20 carbons in an unbranched chain.
  • In most unsaturated fatty acids, the cis isomer is usually existed and the trans isomer is rare.
  • Unsaturated fatty acids have lower melting points than their saturated counterparts.

Cis

slide36

Fatty Acids

Saturated fatty acids are solids at room temperature.

Packed together  Maximum London dispersion forces

slide37

Fatty Acids

Unsaturated fatty acids are liquids at room temperature.

Can not packed together  London dispersion forces

Cis

slide38

Esters

In an ester, the H in the

carboxyl group is replaced

by an alkyl group.

O



CH3 —C—O —CH3

ester group

slide39

Soaps

  • Natural soaps are sodium or potassium salts of fatty acids.
  • They are prepared from a blend of tallow and coconut oils (triglycerides).
  • Triglycerides are triesters of glycerol.
  • the solid fats are melted with steam and the water insoluble triglyceride layer that forms on the top is removed.

CH2 – CH – CH2

OH

OH

OH

1,2,3-Propanetriol

(glycerol, glycerin)

slide40

Soaps

  • Preparation of soaps begins by boiling the triglycerides with NaOH. The reaction that takes place is called saponification.
  • Boiling with KOH gives a potassium soap.
slide41

Soaps

Hydrophobic part: nonpolar

Hydrophilic part: polar (remains in contact with environment)

slide42

Soaps

When soap is mixed with dirt (grease, oil, and …), soap micelles “dissolve” these nonpolar, water-insoluble molecules.

slide43

Chemical properties of Carboxylic Acids

1- They are weak acids.

Substituents of high electronegativity, especially -OH, -Cl, and -NH3+, near the carboxyl group increase the acidity of carboxylic acids.

2- Reaction with bases:

They react with NaOH, KOH, NH3, and other strong bases to form water-soluble salts.

slide44

Chemical properties of Carboxylic Acids

3- Fischer Esterification:

- A carboxylic acid reacts with an alcohols to form an ester.

- Using an acid catalyst such as concentrated sulfuric acid.

The best way to prepare an ester.