Synthesis of Benzoic acid

Definition & Terminology

·       Generic name : Benzoic acid

·       Structure

·       Chemical name :- Benzoic acid

·       Pharmacological use  preservative

Materials

- Benzyl alcohol.

- Anhydrous sodium carbonate.

- Permanganate potassium or dichromate potassium .

- Sulfuric acid (cons ) H₂SO₄ OR ( HCL ) cons.

- Hydrogen peroxide H₂O₂

- H₂O water

Principles

Benzoic acid synthesized as follow.

   

Procedures (methods):-

1.    Place(4) gm of anhydrous Na₂CO₃ , 200ml of H₂O (9) (0.05) mole) of kMnO4 of porous porcelain in 500 mg r.b.f

2.    Boil the mixture gently until the reaction is comp ( 60-90) minutes . until the liquid running down from the condenser . contains no oil drops of unchanged to luen

3.    Allow to cool add 50% H₂O₂  drop – wise with shaking until the color of kMnO4 disappear and filter off the precipitated  manganese dioxid

4.    Acidify with con. HCL , cool and then filter off the precipitated benzoic acid at pump or wash with cold water . Recrystallize from about 200 ml boiling water .

      Results :-              

Name of preparation	Test	Specification
Benzoic acid	Description	Crystals or crystalline powder
	Colour	Colourless crystals or white ( powder)
	Odour	Very slight characteristic odour
	Weight
	Melting point	(122- 124 ) C
	Solubility	1.  1.Easy dissolved in ( freely ) in ethanol , ether ,chloroform and fixed oil . 2.  Slightly soluble in water

Report

Name of preparation	Test	Specification
Benzoic acid	Description
	Colour
	Odour
	Weight
	Melting point