Lab Preparation of Chloroform (CHCl₃)

Chloroform (CHCl₃) is an important trihalogen derivative of methane.

Principle
Distillation of ethanol or acetone with moist bleaching powder.
CaOCl₂ + H₂O → Ca(OH)₂ + Cl₂

a. From Ethanol
i. Oxidation of Ethanol
C₂H₅OH + Cl₂ → CH₃CHO + 2 HCl 

ii. Chlorination of Ethanal
CH₃CHO + 6 Cl₂ → CCl₃CHO + 3 HCl

iii. Hydrolysis of Chloral
2 CCl₃CHO + Ca(OH)₂ → 2 CHCl₃ + (HCOO)₂Ca

b. From Acetone

i. Chlorination of Acetone
CH₃COCH₃ + 3 Cl₂ → CCl₃COCH₃ + 3 HCl

ii. Hydrolysis
2 CCl₃COCH₃ + Ca(OH)₂ → 2 CHCl₃ + (CH₃COO)₂Ca

Note: Ca(OH)₂ is used for hydrolysis as it itself contains sufficient water.

Figure

fig. Lab preparation of CHCl₃

Procedure
The mixture of Bleaching powder, water, and ethanol or acetone are kept in R. B. flask. It is gently heated using hot water bath. Chloroform distillates out which is condensed using the condenser. The condensed Chloroform is collected in the receiver.

Purification
The collected Chloroform is washed with NaOH using a separating funnel to neutralize the acidic nature of the mixture. It is then washed using Water. After the washing, it is dried using a separating funnel and redistilled at the temperature around 60°C - 65°C. Pure and dry Chloroform is obtained.