Identify the correct statements for Ethylene dichloride and Ethylidene chloride
(A) They represent structural isomers.
(B) Both are formed by reaction of ethene with chlorine in presence of \( CCl_4 \)
(C) Both the compounds belong to a class of dihalocompounds
(D) Both the compounds are optically inactive.
Choose the correct answer from the options given below.
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (A), (C) and (D) only
Both compounds are dichloroethanes, \( \ce{C2H4Cl2} \). Ethylene dichloride is 1,2-dichloroethane, \( \ce{ClCH2-CH2Cl} \), a vic-dihalide (chlorines on adjacent carbons). Ethylidene chloride is 1,1-dichloroethane, \( \ce{CH3-CHCl2} \), a gem-dihalide (both chlorines on one carbon).
(A) They represent structural isomers. — Correct. Same molecular formula \( \ce{C2H4Cl2} \), but the chlorine atoms are in different positions: they are position isomers, a kind of structural isomerism.
(B) Both are formed by reaction of ethene with chlorine in presence of \(CCl_4\) — Incorrect. Chlorine adds across the double bond, one atom to each carbon, so only the vic-dihalide is formed:
\( \displaystyle \ce{CH2=CH2 + Cl2} \xrightarrow{\ce{CCl4}} \ce{ClCH2-CH2Cl} \)
Ethylidene chloride is obtained instead, for example, by adding two molecules of HCl to ethyne (Markovnikov addition both times):
\( \displaystyle \ce{HC#CH + 2HCl -> CH3-CHCl2} \)
(C) Both the compounds belong to a class of dihalocompounds — Correct. Each has two halogen atoms; they are dihaloalkanes.
(D) Both the compounds are optically inactive. — Correct. Neither has a carbon with four different groups: in \( \ce{ClCH2-CH2Cl} \) each carbon has two H atoms, and in \( \ce{CH3-CHCl2} \) the substituted carbon has two Cl atoms. With no chiral centre, neither is optically active.