XII Chemistry BIEK Topic - Carboxylic Acid COOH

Carboxylic Acid COOH
Definition
Organic compounds that contain monovalent functional group - COOH are called Ketones.




General Formula
They are denoted by R may be any alkyl group. The general formula for ketone is

CnH2n+1 - COOH

Where n may be any natural number.




Structure
The Structural formula of Carboxylic Acid shows that it contains a carbonyl group.

ROH-C=O


Examples

Acetic Acid (CH3COOH)
Preparation
Carboxylic Acid can be prepared by the following methods.


1. From Grignard's Reagent

In presence of dry ether and halogen acid when Grignard's reagent with carbondioxide then Carboxylic Acid is formed.

R-Mg-X + O=C=O ----> COOR-Mg-X ----> RCOOH + MgX2

CH3-Mg-X + 0=C=0 ----> COOCH3-Mg-X ----> CH3COOH + MgX2


2. From Oxidation of Alcohol

In presence of oxidizing agent such as a mixture of K2Cr2O7 and concentrated K2SO4, when primary alcohol is oxidized then aldehyde is form, which on further oxidation convert into Carboxylic Acid.

RCH2-OH ----> RCHO ----> RCOH-O

CH3CH2-OH ----> CH3CHO ----> CH3COH=O


3. From Dehydrogenation of Alcohol

In presence of catalyst Co - Mo couple, when primary alcohol is heated at elevated temperature then aldehyde is formed, which in presence of a mixture of oxidizing agent such as K2Cr2O7 and concentrated H2SO4 convert into Carboxylic Acid.

RCH2-OH ----> RCHO ----> RCOH-O

CH3CH2-OH ----> CH3CHO ----> CH3COH=O


4. From Ethyne

This method is used for the preparation of acetaldehyde. In presence of catalyst H2SO4 and HgSO4 when ethyne reacts with water than unstable, intermediate vinyle alcohol is formed which on rearrangement of atoms convert into acetaldehyde.

H-C≡C-H + H-OH ----> C2H3OH ----> CH3-CHO ----> CH3-COOH




Uses of Carboxylic Acid
1. Carboxylic Acids are used as laboratory reagents.

2. Acetic acid is used as solvent for phosphorus, sulphur, gums and resins.

3. It is widely used in artificial leather production.

4. Acetic acid is used to prepare acetates, esters and cellulose acetate silk.

5. After colouring, it is used as vinegar.