Carbonyl Compounds

ALDEHYDES, KETONES, AND CARBOXYLIC ACIDS - PART I

Used as a solvent, starting material and reagent

Benzaldehyde - Used in perfumery and in dye industries. Acetone and ethyl methyl ketone are common industrial solvents

Acetaldehyde - Used primarily as a starting material in the manufacture of aceticacid, ethyl acetate, vinyl acetate, polymers and drugs

Formaldehyde - Formalin (40%) solution used to preserve biological specimensand to prepare bakelite, urea-formaldehyde glues and other polymeric products

Nomenclature of Carbonyl Group

Structure of Carbonyl Group

Uses of Aldehydes and Ketones

Carbonyl group is a functional group composedof a carbon atom double bonded to an oxygen atom

R H

O

R R

O

Aldehydes Ketones

C

O

C+

O-

Cσ-bondsp 2

sp2 O..

..

C

Л-bondsp 2

sp2 O..

.. C120o

120o

120o

O..

..

Aldehydes

Ketones

HCHOCH3CHO(CH3)2CHCHO

FormaldehydeAcetaldehydeIsobutyraldehyde

MethanalEthanal2-Methylpropanal

3-Methylcyclohexanecarbaldehyde

2-MethoxypropanalPentanalProp-2-enal

Pentan-2-one2,4-Dimethylpentan-3-one

4-Methylpent-3-en-2-one

2-Methylcyclohexanone

Benzene- 1,2-dicarbaldehyde

γ-Methylcyclohexanecarbaldehyde

α-Methylcyclohexanone

α-MethoxypropionaldehydeValeraldehydeAcrolein

Phthaldehyde

m-Bromobenzaldehyde 3-Bromobenzenecarbaldehydeor3-Bromobenzaldehyde

Methyl n-propyl ketoneDiisopropyl ketone

Mesytil oxide

CH3CH(OCH3)CHOCH3CH2CH2CH2CHOCH2=CHCHO

CH3COCH2CH2CH3(CH3)2CHCOCH(CH3)2

(CH3)2C=CHCOCHCH3

Structure Common Name IUPAC Name

CHOH3C

CHO

CHO

O

CH3

CHO

Br

Carboxylic acids

ALDEHYDES, KETONES, AND CARBOXYLIC ACIDS - PART II

• Methanal (HCHO) is a gas at room

temperature

• Ethanal (CH3CHO) is a volatile liquid

• The boiling points of aldehydes and

ketones are higher than

hydrocarbons and ethers of similar

molecular mass.

• Aldehydes and ketones have lower

boiling point than those of alcohols

of similar molecular mass

• The lower members of aldehydes

and ketones are miscible with water

due to the formation of hydrogen

bond with water

From primary alcohols and aldehydes

From alkylbenzenes

From nitriles and amides

From Grignard reagents

From Acyl halides and anhydrides

From Esters

Preparation of Carboxylic acids

Physical Properties

Classi�cation Structure of Carboxyl Group

NaHSO3

HCN

H2N-Z

Alcohols

(Ammonia Derivates)

Alpha-H containing carbonyl compounds give Aldol reaction

• Monocarboxylic acids contain one -COOH group • Dicarboxylic acids contain two -COOH groups

Sources

HCOOH

CH3COOH

C3H7COOH

Acetic acid

Butyric acid

Vinegar(Latin: acetum)

Rancid butter(Latin: butyrum)

Formic acid Red ant(Latin: formica)

Formula SourceCommon Name

Aldehydes without alpha-H undergo Cannizzaro's reactionEster (Given by two equivalents

of an aldehyde) Tishchenko reaction

i) RMgX

ii) H3O+

OH-

OH-

Zn-HgConc. HCl

NH2-NH2OH-/Δ

LIAlH4 or NaBH4

Oxidation Carboxylic Acids

Alcohol

Alkane(Wolf Kishner reduction)

Alkane(Clemmensen reduction)

Al(OR)3

Chemical Properties

C

R

R SO3Na

OH

N-ZC

R

R

C

R

R CN

OH

O

H HOC

R

R

O C

R

R

δ+ δ- δ-δ+ δ+ δ+

δ-

CRO H

O

Carbonyl Compounds

C+

H

-O

O..

..

C

H

-O

O+

..C

H

O

O..

..

RCH2OHalkaline KMnO4

H3O+ RCOOH

CH3(CH2)8COOHCH3(CH2)8CH2OHCrO3.H2SO4

Jones reagent

KMnO4.KOHHeat

Benzoic acid

H3O+

CH3 COOK COOH

KMnO4.KOHHeat

Benzoic acid

H3O+

CH2CH2CH3 COOK COOH

Ethanamide Ethanoic acidH3O+

CH3CONH2 CH3COOH + NH3

Benzamide Benzoic acid

H3O+

+ NH3

CONH2 COOH

Ethanamide

+H -OHorRCN

H2ORCOOH

+H -OHor

R C NH2

O

Ethyl butanoate

Butanoic acid

NaOHH3O+

CH3CH2CH2COOC2H5 CH3CH2CH2COONa

CH3CH2CH2COOH

+ C2H5OH

Ethyl benzonate Benzoic acid

H3O+

+ C2H5OH

COOC2H5 COOH

R-Mg-X + O=C=ODry ether

RCOOHCO-MgX+

O

RH3O+

RCOCl

RCOOH

RCOOHRCOO- H3O+-OH/ H2O

–Cl H2O +

–Cl +

2C6H5COOHH2O(C6H5CO)2O

Benzoic acidBenzoic anhydride

C6H5COOHH2OC6H5COOCOCH3Benzoic acid

CH3COOHEthanoic acidBenzoic ethanoic

anhydride

+

1

2

3

4

5

6

ALDEHYDES, KETONES, AND CARBOXYLIC ACIDS - PART III

• Aliphatic carboxylic acids up to nine carbon

atoms are colourless liquids at room

temperature with unpleasant odours.

• Lower aliphatic carboxylic acids are

miscible in water.

• Carboxylic acids have higher boiling points

than aldehydes, ketones and carboxylic

acids of similar molecular masses.

• Aliphatic carboxylic acids may show

oscillation or alternation e�ect in which the

melting point of an acid with even number

of carbon atoms is more than that of the

next odd homologue.

• The pure or water free form of acetic acid is

also called glacial acetic acid.

Physical Properties• Methanoic acid: Rubber, textile, dyeing,

leather and electroplating industries

• Ethanoic acid: Used as solvent and as

vinegar in food industry

• Hexanedioic acid: Used in the manufacture

of nylon-6, 6

• Esters of benzoic acid: Used in perfumery

• Sodium benzoate: Used as a food

preservative

• Higher fatty acids: Used for the

manufacture of soaps and detergents

Reactions Involving Cleavage of O–H Bond

Reactions Involving Cleavage of C–OH Bond

Reactions Involving –COOH Group

Uses of Carboxylic acid

Chemical Properties

Formation of anhydride

Halogenation

Ring Substitution

Esterification

Reactions with PCl5, PCl3 and SOCl2

Reaction with ammonia

C CRO H

HOR

O

O

H+

RCOOH + R’OH RCOOR’ + H2O

H+

RCOOH + PCl5 RCOCl + POCl3 + HCl

H+

3RCOOH + PCl3 3RCOCl + H3PO3

H+

RCOOH + SOCl2 RCOCl + SO2 + HCl

(i) X2/ phosphorus

α - Halocarboxylic acid

(iI) H2OR-CH2-COOH R-CH - COOH

XX = Cl, Br

2R-COOH + 2Na 2R-COONa+ + H2–

Sodium carboxylate

R-COOH + NaOH R-COONa+ + H2O–

–R-COOH + NaHCO3 R-COONa+ + H2O + CO2

CO

OHH3C C

O

OHH3C

Ethanoic anhydride

CO

OCH3 C

OCH3+

H+, ∆

or P2O5, ∆

m-Nitrobenzoic acid

COOH COOH

NO2Conc. H2SO4

Conc. HNO3

m - Bromobenzoic acid

COOH COOH

BrConc. H2SO4

Br2/ FeBr3

Ammonium acetate AcetamideCH3COOH CH3COONH4

- ++ CH3CONH2+ NH3

-H2O∆

Ammonium benzoate Benzamide

+ NH3

COOH CONH2

-H2O

∆COONH4

- +

Ammonium phthalate

Phthalimide

+ NH3

-NH3Strongheating

COOH

COOH

COONH4- +

COONH4- +

CONH2

CONH2

NH

C

O

O

C

-2H2O

∆

Reactions Involving –COOH Group

Reduction

Decarboxylation

(i) LiAlH4/ ether or B2H6

(iI) H3O+R-COOH RCH2OH

NaOH & CaOHeat

R-COONa R-H + Na2CO3

3

4

1

2

1

2

3

4