Carboxylic Acids

CHAPTER 12

CARBOXYLIC ACIDS

IUPAC Nomenclature of Carboxylic Acid

Carbon atoms

Common name

IUPAC name

Chemical formula

1

Formic acid

Methanoic acid

HCOOH

2

Acetic acid

Ethanoic acid

CH3COOH

3

Propionic acid

Propanoic acid

CH3CH2COOH

4

Butyric acid

Butanoic acid

CH3(CH2)2COOH

5

Valeric acid

Pentanoic acid

CH3(CH2)3COOH

6

Caproic acid

Hexanoic acid

CH3(CH2)4COOH

7

Enanthic acid

Heptanoic acid

CH3(CH2)5COOH

8

Caprylic acid

Octanoic acid

CH3(CH2)6COOH

9

Pelargonic acid

Nonanoic acid

CH3(CH2)7COOH

10

Capric acid

Decanoic acid

CH3(CH2)8COOH

12

Lauric acid

Dodecanoic acid

CH3(CH2)10COOH

16

Palmitic acid

Hexadecanoic acid

CH3(CH2)14COOH

18

Stearic acid

Octadecanoic acid

CH3(CH2)16COOH

3,3-dimethylcyclohexane carboxylic acid

NOMENCLATURE OF THE THE SALTS OF CARBOXYLIC ACIDS

Physical properties • A weak acid. • Polar and form hydrogen bonds with each other, exist as dimeric pairs

• Lower carboxylic acid (C1-C4) misible with water, >C5 less soluble due to the increasing of the R chain.

PREPARATIONS OF THE CARBOXYLIC ACIDS A) Oxidation of Alkybenzenes

B) Oxidation of primary alcoholS

c) Hydrolysis of Nitriles

d) Carbonation of Grignard Reagents - the alkyl halide is converted to corresponding grignard reagent then followed by treament with CO2. - The product has more carbon than the starting material

DERIVATIVES OF CARBOXYLIC ACIDS

Structure and nomenclature of the carboxylic acid derivatives 1) EsterS

2)Acid Chlorides

3) Acid Anhydrides

4) Amides

NUCLEOPHILIC ACYL SUBSTITUTION REACTIONS

O R C L

+

L = Cl, OH,OR, NR2, OCOR

Nu:-

H Nu: H-Nu: H-OH, H-OR, H-NR2, H-OCOR

O R C Nu

L:-

+

H L

General mechanism Nuetral nucleophile

-ve nucleophile

Acid catalyzed

a) Nuc Acyl Subst. reaction of ACID CHLORIDES

b) Nuc Acyl Subst. reaction of ACID ANHYDRIDES

C) Nuc Acyl Subst. reaction of CARBOXYLIC ACIDS

d) Nuc Acyl Subst. reaction of ESTERS

e) Nuc Acyl Subst. reaction of AMIDES

NUCLEOPHILIC ADDITION REACTIONS OF CARBOXYLIC ACID DERIVATIVES •

Reduction with LiAlH4 -all acid derivatives can be reduced to 1

o

ROH except amide

- amides is reduced to amines

O C R NR2

LiAlH4

H2O, H+

RCH2NR2

2) Reaction with Grignard Reagents -esters and acid chloride react with grignard reagent to produce 3o ROH

REACTION OF ACID DERIVATIVES INVOLVING CARBANIONS A) Malonic ester Synthesis – to prepare disubstituted acetic acids O C

OEt

CH2 C

OEt = OCH2CH3

OEt

O

H H

C H

R

O H

C OH

C R

O C OH

Mechanism:

How to prepare 2-isopropylpentanoic acid from malonic ester?

b) Claisen Condensation – an ester is converted to β-keto ester