Carbon Compounds

CARBON COMPOUNDS


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CARBOXYLIC ACID



       Carboxylic acids are the compounds containing the carboxyl functional group   in their molecule. Their general formula is CnH2n+1COOH. The simplest carboxylic acid is methanoic acid (formic acid) having molecular formula HCOOH.

Fatty Acids

       Fatty acids are the monocarboxylic acids which contain a long chain of carbon atoms. The minimum number of carbon atoms in fatty acids is 15. These are called as fatty acids because these are present mostly in fats and oils. For example, palmitic acid (C15H31COOH), oleic acid (C17H33COOH) and stearic acid (C17H35COOH).

Uses of Fatty Acids

       Fatty acids are used in eatables, cold drinks, soaps and in medicines.

Nomenclature of carboxylic Acids

       According to IUPAC system, the name of carboxylic acid is derived by replacing the terminal ‘e’ of the name of the corresponding alkane with ‘oic acid’.

Common Name IUPAC Name Molecular Formula
Formic acid Methanoic acid Structure of Formic acid
Acetic acid Ethanoic acid Structure of Acetic acid
Propanic acidPropanoic acid Structure of Propanic acid
Butric acid Butanoic acid Structure of Butric acid


Ethanoic Acid or Acetic Acid

Ethanoic acid can be prepared by following methods :

1. From Ethanol


Preparation Of Acetic Acid Using Ethanol and Acetobactor


Ethanoic acid can also be prepared by oxidation of ethanol in the presence of oxidizing agent K2Cr2O7 and H2SO4.



Preparation Of Acetic Acid Using Ethanol and Oxidising Agent


2. From Methyl Cyanide

       When water is added into methyl cyanide then upon hydrolysis ethanoic acid is produced.



Preparation Of Acetic Acid From Methyl Cyanide


Properties of Ethanoic Acid

Physical Properties

       Following are the physical properties of ethanoic acid:

  1. It is a colourless liquid with pungent odour.
  2. It freezes below 16.50C.
  3. Its boiling point is 1180C.
  4. It is soluble in water.


Chemical Properties

       Following are the important chemical reactions of acetic acid :

1. Reaction with Alcohols or Esterification

       When acetic acid reacts with ethanol in the presence of conc. H2SO4 as catalyst sweet smelling esters are formed. This process is called esterification.

process of esterification


2. Reaction with Sodium Metal

       Acetic acid reacts with sodium metal to produce sodium acetate and hydrogen gas.



Reaction Of Acetic Acid With Sodium Metal


3. Decarboxylation Reaction or Reaction with Soda Lime

       Loss of carbon dioxide from molecule of sodium or potassium salt of carboxylic acid is called decarboxylation. In this reaction, when sodium or potassium salts of carboxylic acids are heated after mixing with soda lime (NaOH + CaO) then methane gas is produced.

Process of Decarboxylation


Preparation of Soda Lime

       Sodalime can be prepared for decarboxylation reaction by mixing 3 parts by volume of NaOH with 1 part by volume of CaO.

4. Reaction with Ammonia

       Acetic acid reacts with ammonia to form acid amides.

Reaction Of Acetic Acid With Ammonia


Uses of Acetic Acid

       Following are the uses of acetic acid:


  1. It is used as a solvent and chemical reagent in laboratories.
  2. It is used as a preservative.
  3. It is used in preparation of acetone and acetic anhydride.
  4. It is used in coagulation of latex of rubber.
  5. It is used as vinegar in cooking.
  6. It is used in manufacture of rayon and plastics.