Chemical properties of tricholoromethane

Chemical properties of trichloromethane are:

Oxidation :

Oxidation and Reduction of Chloroform.JPG

Phosgene is extremely poisonous gas. To use chloroform as an anaesthetic agent, it is necessary to prevent the above reaction. The following two precautions are taken when chloroform is stored.

(a) It is stored in dark blue or brown coloured bottles, which are filled upto the brim.

(b) 1% ethyl alcohol is added. This retards the oxidation and converts the phosgene

formed into harmless ethyl carbonate.

COCI2 + 2C2H5 OH ——→ ( C2H5O)2 CO + 2HCI


Zn / HCl
CHCI3 + 2H ———→ CH2 CI2 + HCI
Zn / H2O
CHCI3 + 6H ———→ CH4 + 3HCI


UV light
CHCI3 + CI2 ———→ CCI4 + HCI
Carbon tetrachloride

Hydrolysis :

Chlorination and Hydrolysis of Chloroform.JPG

Formation of Tear Gas

Nitration : The hydrogen of the chloroform is replaced by nitro group when it is treated with concentrated nitric acid. The product formed is chloropicrin or trichloronitro methane or nitro chloroform. It is a liquid, poisonous and used as an insecticide and a war gas.

CHCI3 + HONO2 ————→ CNO2 CI3 + H2O
Nitric acid Chloropicrin (Tear gas)

Reimer-Tiemann reaction :

C6H5OH + CHCI3 + 3NaOH ———→C6 H4 OH.JPG + 3NaCI + 2H2O
Hydroxy benzaldeh yde(salicy laldehyde)

Carbylamine reaction(Isocyanide test) : This reaction is actually the test of primary amines. Chloroform, when heated with primary amine in presence of alcoholic potassium hydroxide forms a derivative called isocyanide which has a very offensive smell.

RNH2 + CHCI3 + 3KOH (alc.) ———→ RNC + 3KCI + 3H2O

This reaction is also used for the test of chloroform.

Uses of Chloroform

(i) It is used as a solvent for fats, waxes, rubber, resins, iodine, etc.

(ii) It is used for the preparation of chloretone (a drug) and chloropicrin (Insecticide).

(iii) It is used in laboratory for the test of primary amines, iodides and bromides.

(iv) It can be used as anaesthetic but due to harmful effects it is not used these days for this purpose.

(v) It may be used to prevent putrefaction of organic materials, i.e., in the preservation of anatomical species.

Tests of chloroform

(i) It gives isocyanide test (Carbylamine test).

(ii) It forms silver mirror with Tollen's reagent.

(iii) Pure Chloroform does not give white precipitate with silver nitrate

No comments: