Action of chlorine on unsaturated polychloro compounds in an acid medium

Summary

• 1. It was shown that compounds of the type CCl₂ = CH(CH₂)nX react with chloride in a neutral medium with formation of a mixture of saturated polychloro hydrocarbons and hydrogen chloride. When this reaction is carried out in presence of concentrated sulfuric acid at 0–15° without irradiation, smooth addition of chloride at the double bond occurs.

• 2. It was found that reaction of compounds of structure CCl₂ = CH(CH₂)n X = X = H, Cl, COOH, CCl₃) with chlorine proceeds by “conjugated addition” only when the medium is an concentrated strong mineral acid (sulfuric or perchloric) with formation (after hydrolysis) of a α- chloro carboxylic acids. In phosphoric acid, and also in carboxylic acids, neutral chlorination products are obtained.

• 3. When chlorine reacts with 3,3,3-trichloropropene in glacial acetic or concentrated sulfuric acid, 2,3,3,3-tetrachloropropyl acetate or sulfate is obtained, respectively. This confirms that the trichloromethyl group shows the orienting effect characteristic of an electron-accepting group.