Trichloroacetaldehyde preparation method

Yield: not specified
Reagents: ethyl alcohol, chlorine, sulfuric acid, calcium oxide
100 ml of absolute ethyl alcohol is placed in a ice cooled flask with a black light 10cm away from the flask irradiating it with Ultraviolet light. to the flask a bubbler is added to which a current of dry chlorine gas is passed by maintaining the temperature below 10° C. The chlorine is quickly absorbed, and, after a short time, the reaction flask is connected with a reflux condenser. By gently warming of the liquid to 60° C the saturation of the solution is continued with chlorine gas until it is fully absorbed. The chlorination reaction is complete when the solution reaches density of 1.4 g/ml, then the liquid is gently boiled for a short time and allowed to cool after which it is cautiously mixed with an equal volume of concentrated sulfuric acid. During this addition hydrochloric acid and ethyl chloride are evolved. Then the reaction mixture is distilled and the distillate is neutralized with calcium oxide or carbonate and redistilled. Further purification is performed by fractionation. Remaining ethyl chloride with hydrogen chloride distills off first. Between 70° C and 90° C ethyl alcohol passes over, and from 90° C chloral starts to distill. Chloral is a colorless mobile liquid, which boils at 94.5° C. When mixed with about one-fifth of its weight of water, the mixture slowly solidifies to a crystalline mass of chloral hydrate.