Consider the following sequence of reactions: p-toluidine NaNO ₂, HCl, 0-5^ C (A) phenol, NaOH (B) (i) CHCl ₃ , NaOH, (ii) H ₃ O ^+ (C) The total number of sp ^2 hybridized carbon atoms in the major product (C) is ________.

Step-by-step solution

Step 1: p-toluidine (4-methylaniline) reacts with NaNO ₂ and HCl at 0-5^ C to form p-toluenediazonium chloride (A). Step 2: The diazonium salt (A) couples with phenol in a basic medium. The coupling takes place at the para position of phenol, producing 4-(4-methylphenylazo)phenol (B). Step 3: Compound (B) is subjected to the Reimer-Tiemann reaction conditions ( CHCl ₃ and NaOH , followed by acidic workup). The phenolic - OH group strongly activates the ring towards electrophilic aromatic substitution. Since the par