Benzaldehyde is treated with concentrated $\mathrm{NaOH}$ (Cannizzaro reaction). The products are:
- Salicylaldehyde and water
- Sodium benzoate and benzyl alcohol
- Benzoic acid only
- Benzyl alcohol only
Show answer and solution
Correct answer: B. Sodium benzoate and benzyl alcohol
**Cannizzaro reaction** is the disproportionation of an aldehyde with **no $\alpha$-hydrogen** under concentrated alkali. One molecule of the aldehyde is oxidised, one is reduced.
For benzaldehyde + NaOH (conc.):
- One PhCHO is *oxidised* to PhCOO⁻Na⁺ (**sodium benzoate**).
- One PhCHO is *reduced* to PhCH₂OH (**benzyl alcohol**).
So the product mix is option C. Acidifying the workup converts the sodium benzoate to benzoic acid, but the raw Cannizzaro products are as written.
**Why option A is wrong on its own.** Plain oxidation of benzaldehyde with stronger oxidants gives benzoic acid alone
that's *not* Cannizzaro — Cannizzaro requires the simultaneous reduction half.