Which of the following statements are correct?
A. Dry ether is used in Wurtz reaction
B. Grignard reagent is an example of organometallic compound.
C. Bond cleavage of \(C-Cl\) is easier in haloarene than haloalkane
D. Chlorobenzene does not show Friedel Craft reaction.
E. Enantiomers differ with respect to rotation of plane polarized light.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → A, B, E only
(A) Dry ether is used in Wurtz reaction — Correct. Alkyl halides react with sodium in dry ether to give hydrocarbons with double the number of carbon atoms:
\( \ce{2RX + 2Na} \xrightarrow{\text{dry ether}} \ce{R-R + 2NaX} \)
(B) Grignard reagent is an example of organometallic compound. — Correct. RMgX contains a carbon–magnesium bond, which makes it an organometallic compound:
\( \ce{R-X + Mg} \xrightarrow{\text{dry ether}} \ce{R-MgX} \)
(C) Bond cleavage of C–Cl is easier in haloarene than haloalkane — Incorrect. In chlorobenzene the lone pair on Cl is in resonance with the ring, giving the C–Cl bond partial double-bond character; the carbon is also sp2 hybridised. The bond is shorter and stronger, so it is harder to break than in haloalkanes.
(D) Chlorobenzene does not show Friedel Craft reaction. — Incorrect. Chlorobenzene undergoes Friedel–Crafts alkylation and acylation in the presence of anhydrous \( \ce{AlCl3} \), giving mainly the ortho and para products:
\( \ce{C6H5Cl + CH3Cl} \xrightarrow{\text{anhyd. }\ce{AlCl3}} \text{o-/p-}\ce{ClC6H4CH3 + HCl} \)
\( \ce{C6H5Cl + CH3COCl} \xrightarrow{\text{anhyd. }\ce{AlCl3}} \text{o-/p-}\ce{ClC6H4COCH3 + HCl} \)
(E) Enantiomers differ with respect to rotation of plane polarized light. — Correct. Enantiomers rotate plane polarised light by the same angle but in opposite directions (one d, the other l).