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Question #44395

Difficulty: 8/10 | 🟢 Free

The Question

Consider four phenolic compounds: Phenol (I), 4-Chlorophenol (II), 4-Methylphenol (III), and 4-Nitrophenol (IV). These compounds are subjected to the Reimer-Tiemann reaction conditions using $CHCl_3$ and aqueous $NaOH$ at $340\text{ K}$ . Determine the correct decreasing order of their initial reaction rates and the exact nature of the attacking electrophile in the rate-determining step.

Options

A.
III > I > II > IV ; Neutral electrophile ( $:CCl_2$ )
B.
III > II > I > IV ; Neutral electrophile ( $:CCl_2$ )
C.
III > I > II > IV ; Positively charged electrophile ( $^+CHCl_2$ )
D.
I > III > II > IV ; Positively charged electrophile ( $^+CCl_3$ )

Check Your Answer

Correct Answer

Step-by-Step Solution

Explanation

How the Examiner Thinks

Mechanism_Trap

Don't get tricked by the process! Learn the mechanical traps used in competitive exam questions.

Concepts Behind This Question

Reimer-Tiemann Reaction|Aryl Halide Resonance|C-X Bond Polarization and Polarizability

Why This Question Is Tricky

Common Mistakes

This question tests two critical traps.

First, the nature of the electrophile in the Reimer-Tiemann reaction is the neutral dichlorocarbene ( $:CCl_2$ ), not a carbocation.

Because it is neutral, the reaction rate is highly sensitive to the nucleophilicity of the aromatic ring.

Second, students often conflate 'ortho/para directing' with 'activating'.

While halogens (like in 4-chlorophenol) direct ortho/para due to resonance (+M), they are net deactivating due to a dominant inductive effect (-I).

Therefore, 4-chlorophenol reacts slower than unsubstituted phenol, trapping students who assume the +M effect accelerates the reaction.

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	Alcohols, Phenols, and Ethers - Class 12
Concept	Reimer-Tiemann Reaction
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free