Laboratory Preparation Of Chloroform Chemistry
Molecular Formula:- CHCL3 IUPAC Name:- Trichloromethane Common Name:-Chloroform Principle:- Chloroform in laboratory is preapared by heating the paste of bleaching powder with Ethanol or Acetone.In this reaction/Process,the bleaching powder acts as oxidising agent,chlorinating agent and hydrolysing agent. Steps:- 1)By using Ethanol( C2H5OH ) a)Hydrolysis of bleaching powder. CaOCl2+H2O ——-> Ca(OH)2 + Cl2 b)Oxidation of Ethanol into Ethanal by Cl2 C2H5OH + Cl2 ——-> CH3CHO + 2HCL c)Chlorination of ethanol into chloral. CH3CHO + 3Cl2 ——-> CCl3CHO + 3HCL CCl3CHO is Chloral ( 2,2,3-Trichloroethanal ) d)Hydrolysis of chloral by Ca(OH)2 Ca(OH)2 + 2CCl3-CHO ——-> 2CHCl3 + (HCOO)2Ca
Here Chloroform is produced.
2)By using Acetone. Steps:- a)Hydrolysis of Bleaching Powder. CaOCl2 + H2O ——-> Ca(OH)2 + Cl2 b)Chlorination Of Acetone into Trichloroacetone. CH3COCH3 + 3CL2 ——-> CCL3-CO-CH3 + 3HCL c)Hydrolysis of trichloroacetone by Ca(OH)2 into CHCL3 2CCL3-CO-CH3 + Ca(OH)2 ——-> 2CHCL3 + (CH3COO)2Ca
Here Chloroform is produced.
- Purification:-Hence,lab prepared Chloroform is impure and may contain acids and water as impurities.Acidic impurities are removed by mixing the Chloroform with dil.NaOH/Na2CO3 dil.NaOH + HCl ——-> NaCl + H2O Water soluble impurities are removed by washing the Chloroform with cold water. Remaining water impurities are removed by adding anh.CaCl2 CHCL3 + H2O +anh.CaCl2 ——-> CHCL3+CaCl2.H2O Finally,Chloroform is refined by distillation process carried at about 60°C-62°C[Since BPT of CHCL3=61°C]