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Question #45040

Difficulty: 8/10 | 🟢 Free

The Question

Consider the following two independent reactions:

Reaction I: \ce{2,4,6-tri-tert-butylbenzaldehyde} is heated with concentrated aqueous \ce{NaOH} at 373 K, followed by careful acidification, yielding two major organic products $P$ and $Q$ .

Reaction II: Orthophosphorous acid (\ce{H3PO3}) is heated at 473 K, undergoing auto-redox disproportionation to yield an acid $W$ and a toxic gas $X$ .

Let $c_1$ and $c_2$ be the total number of $sp^2$ hybridized carbon atoms in one molecule of $P$ and $Q$ , respectively. Let $n$ be the number of \ce{P-H} bonds in one molecule of the gaseous product $X$ .

Calculate the value of the expression: $(c_1 \times c_2) + n$ .

Options

A.
9
B.
45
C.
6
D.
42

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

Auto-Redox in Oxyacids|Cannizzaro Mechanism|Steric Hindrance (B-Strain)

Why This Question Is Tricky

Common Mistakes

The problem tests the limits of the Cannizzaro reaction by introducing severe steric hindrance (B-strain).

Students typically rote-memorize that aldehydes lacking $\alpha$ -hydrogens undergo disproportionation (Cannizzaro).

However, the bulky ortho \textit{tert}-butyl groups in \ce{2,4,6-tri-tert-butylbenzaldehyde} prevent the necessary bimolecular transition state for hydride transfer.

Instead, the tetrahedral intermediate relieves steric congestion via C-C bond cleavage (deformylation), yielding an arene and formic acid.

The secondary concept tests the auto-redox of oxyacids (\ce{H3PO3} disproportionation) and structural knowledge of the resulting gas (\ce{PH3}), combining advanced organic kinetics with inorganic structural analysis.

The trap option (45) catches students who blindly apply the Cannizzaro mechanism to yield the corresponding alcohol and acid.

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	Redox Reactions - Class 11 Part 2
Concept	Auto-Redox in Oxyacids
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free