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Alcohol aldehydes cetones and carboxylic acids 1

Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

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Page 1: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Alcohol aldehydes

cetones and

carboxylic acids

1

Page 2: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Classes of organic compounds

2

Page 3: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

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

Page 4: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Classification of alcohols (1)

4

Page 5: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

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

Page 6: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Naming alcohols (1)

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Page 7: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Naming alcohols (2)

Dihydroxylic alcohols are called glycols, or

according to IUPAC: -diols;

trihydroxylic alcohols: -triols.

7

Page 8: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

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

Page 9: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

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

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Page 10: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

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

Page 11: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Ethers

11

Page 12: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Physical properties of alcohols

12

Page 13: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Aromatic alcohols

13

Page 14: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Oxidation of aromatic alcohols

14

Page 15: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Phenols(1)

Phenol is soluble in water

because the hydroxyl group

ionizes slightly as a weak

acid.

15

Page 16: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Phenols(2)

Phenol

1,2,5-benzenetriol

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Page 17: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

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

Page 18: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

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-

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Page 19: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Phenols: examples

OH

OH

CH

OH

CH2

NH CH3

adrenaline

OH

OH

CH

OH

CH2

NH2

noradrenaline

Physiologically active aromatic alcohols:

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Page 20: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Alcohol in the body

20

Page 21: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Carbonyl compounds: Aldehydes

and ketones

21

Page 22: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

The polar carbonyl group

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Page 23: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Groups of carbonyl compounds

propanone (acetone) Benzophenone

Aldehydes

Ketones

ethanal benzaldehyde

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Page 24: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Naming aldehydes

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Page 25: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Naming ketones

25

Page 26: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

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.

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Page 27: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Physical properties of carbonyl

compounds (2)

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Page 28: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

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

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Page 29: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Tollens’ test

Ag+ + 1e- Ag (s)

CH3

C H

O

+ 2Ag+ [O]

2Ag(s) +Acetaldehyde

CH3

C OH

O

Acetic acidTollensreagent

Silvermirror

Example:

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Page 30: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

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

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Page 31: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Carboxylic acids

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Page 32: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Preparation of carboxylic acids

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Page 33: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Naturally occurring carboxylic acids

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Page 34: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Naming carboxylic acids

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Page 35: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

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

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Page 36: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Aromatic carboxylic acids

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Page 37: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

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

Page 38: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Physical properties of carboxylic

acids

38

Page 39: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

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

Page 40: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

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.

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Page 41: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Soap formation

41

Page 42: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

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

Page 43: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

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.

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Page 44: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Esters

44

Page 45: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Examples of esters

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Page 46: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Reactions of esters - hydrolysis

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Page 47: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Esters in medicine

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Page 48: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

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

Page 49: Alcohol aldehydes cetones and carboxylic acidsjulivan/medical-chemistry/...Physical properties of carboxylic acids 38 The acidity of carboxylic acids The equilibrium concentrations

Reactions of acid anhydrides

49