Alcohol aldehydes

cetones and

carboxylic acids

1

Classes of organic compounds

2

Alcohols

Alcohols are organic compounds containing

hydroxyl (-OH) group attached to C atom.

In an alcohol, -OH group replaces a

hydrogen atom in an alkane.

In a phenol, -OH group is attached to a

benzene ring.

Methane

3

Classification of alcohols (1)

4

Classification of alcohols (2)

According to the number of -OH groups, there are

monohydroxylic, dihydroxylic and trihydroxylic alcohols.

According to the saturation of C atom chain, alcohols fall into

saturated and unsaturated aliphatic, cyclic and aromatic.

CH3

CH2

CH2

OH

OH CH2

OH

1-propanol(aliphatic alcohol)

cyclohexanol(cyclic alcohol)

phenylmethanol(aromatic alcohol)

CH3

CH2

OH CH2

CH2

OH OH

CH2

CH CH2

OH OH OHethanol(monohydroxylicalcohol)

1,2-ethanediol(dihydroxylicalcohol)

1,2,3-propanetriol(trihydroxylic alcohol)glycerol

5

Naming alcohols (1)

6

Naming alcohols (2)

Dihydroxylic alcohols are called glycols, or

according to IUPAC: -diols;

trihydroxylic alcohols: -triols.

7

Chemical properties of alcohols (1)

Acidic-basic properties: although OH group is polar, alcohols are very weak acids.

The acidic properties of di- and trihydroxylic alcohols are stronger than those of monohydroxylic alcohols. They react with bases producing salts: diols form glycolates, triols - glycerates.

The reaction for identification of -CHOH-CHOH- fragment in various compounds:

CH2

CH2

OH

OH

+ Cu(OH)2 + CuO

O

O

O

CH2

CH2

CH2

CH2

2K+ + 4H2O

blue colourprecipitate

water solubleblue complex compound

KOH2

2-

8

Chemical properties of alcohols (2)

Oxidation of primary alcohols results in formation

of aldehydes, and then aldehydes undergo

further oxidation to carboxylic acids.

Under oxidation of secondary alcohols, ketones

are produced. Ketones are more resistant to

oxidation.

R CH2

OH[O]

-H2OR C

O

H

[O]R C

O

OH

R CH R1

OH

[O]

-H2OR C R1

O

9

Chemical properties of alcohols (3)

Formation of ethers:

Formation of esters with both mineral and

organic acids.

Esters of glycerol and organic acids are

triacylglycerols (fats).

R1 CH2

OH +R2 CH2

OH R1 CH2

O CH2

R2

-+R1 CH2

OH H2SO4 R1 CH2

O SO3

R1 CH2

OH + R COOH R C O CH2

R1

O

10

Ethers

11

Physical properties of alcohols

12

Aromatic alcohols

13

Oxidation of aromatic alcohols

14

Phenols(1)

Phenol is soluble in water

because the hydroxyl group

ionizes slightly as a weak

acid.

15

Phenols(2)

Phenol

1,2,5-benzenetriol

16

Chemical properties of phenols (1)

Phenols are are stronger acids than aliphatic and

aromatic alcohols .

Form salts:

Form ethers:

Form esters:

OH

NaOH

-H2O

ONa

phenol sodium phenolateO

CH3

methyl phenyl ether (anisol)

OCOCH3

phenylethanoate17

Chemical properties of phenols (2)

• Phenols are characterized with one specific

reaction. They can form coloured

compounds reacting with ferric trichloride. In

such reaction phenols form coloured

coordination compounds - ferric phenolates:

FeCl3 + 6C6H5OH = [Fe(OC6H5)6]3- + 6H+ + 3Cl-

18

Phenols: examples

OH

OH

CH

OH

CH2

NH CH3

adrenaline

OH

OH

CH

OH

CH2

NH2

noradrenaline

Physiologically active aromatic alcohols:

19

Alcohol in the body

20

Carbonyl compounds: Aldehydes

and ketones

21

The polar carbonyl group

22

Groups of carbonyl compounds

propanone (acetone) Benzophenone

Aldehydes

Ketones

ethanal benzaldehyde

23

Naming aldehydes

24

Naming ketones

25

Physical properties of carbonyl

compounds (1)

Aldehydes and ketones with up to 4 C atoms in

molecules are volatile liquids of specific odour.

They are soluble in water and in organic

solvents.

Solubility in water decreases with an increase of

a number of C atoms in a chain.

Aldehydes containing 8-10 C atoms in a chain

have odour of flowers and are used in

perfumery.

26

Physical properties of carbonyl

compounds (2)

27

Chemical properties of carbonyl

compounds

Reduction producing alcohols (both aldehydes

and ketones).

Oxidation producing acids (only aldehydes).

CH3

C CH3

O

C CH3

H

OH

CH3

propanone(acetone)

CH3

C H

O[O]

CH3

C OH

O

Acetaldehyde Acetic acid

28

Tollens’ test

Ag+ + 1e- Ag (s)

CH3

C H

O

+ 2Ag+ [O]

2Ag(s) +Acetaldehyde

CH3

C OH

O

Acetic acidTollensreagent

Silvermirror

Example:

29

Benedict’s test

Example: CH3

C C

OH

H

O

+ Cu2+ Cu2O(s) + CH3

C C

OH

OH

O

2-Hydroxypropanal Benedict'sreagent

Brick-redsolid

2-Hydroxypropanoic acid

30

Carboxylic acids

31

Preparation of carboxylic acids

32

Naturally occurring carboxylic acids

33

Naming carboxylic acids

34

Some common names of

carboxylic acids

Common IUPAC Formula

Formic methanoic HCOOH

Acetic ethanoic CH3COOH

Propionic propanoic CH3CH2COOH

Butyric butanoic CH3(CH2)2COOH

Capric decanoic CH3(CH2)8COOH

Lauric dodecanoic CH3(CH2)10COOH

Stearic octadecanoic CH3(CH2)16COOH

35

Aromatic carboxylic acids

36

Polar functional groups in

carboxylic acids

Carboxylic acids are among the most polar organic compounds because the functional carboxyl group consists of two polar groups: a hydroxyl (-OH) group and a carbonyl (C=O) group.

HC

OH

O

-

+

-

+

37

Physical properties of carboxylic

acids

38

The acidity of carboxylic acids

The equilibrium concentrations of the carboxylic acid

R-COOH and the carboxylate ion R-COO- depend upon pH:

At low pH the acid form predominates, at pH 7.4 the

carboxylate ion predominates.

Carboxylic acids react with bases to produce carboxylate

salts and water. 39

Salts of carboxylic acids

The carboxylic acid salts are solids at room temperature.

Because they are ionic compounds, carboxylic acid salts

of the alkali metals (Li+, Na+, and K+) and NH4+ are

usually soluble in water.

40

Soap formation

41

Cleaning action of soap

One of the problems of using soaps is that the carboxylate end reacts

with ions in water such as Ca2+ and Mg2+ and forms insoluble

substances.

2CH3(CH2)16COO- + Mg2+ [CH3(CH2)16COO-]2Mg2+

Stearate ion Magnesium stearate (insoluble) 42

Esterification

Carboxylic acids, acid chlorides and acid anhydrides

react with alcohols to produce esters.

Esters can also be formed when inorganic acids

(e.g., phosphoric acid) react with alcohols.

43

Esters

44

Examples of esters

45

Reactions of esters - hydrolysis

46

Esters in medicine

47

Acid anhydrides

They form from the combination of two carboxylic

acids and the loss of water.

Examples:

CH2

C O C CH2

O O

CH3

CH3

propanoic anhydride

C O C

O O

benzoic anhydride

CH3

C OH

O

2H+, heat

CH3

C O C CH3

O O

+ H2O

ethanoic acid ethanoic anhydride

48

Reactions of acid anhydrides

49