Total Bromine Atoms in Compound T Synthesis Scheme

To determine the total number of bromine ($\text{Br}$) atoms in one molecule of compound $T$, we trace the step-by-step chemical transformations in each scheme:

Scheme 1: Synthesis of Compound $Q$

1. Reactant $P$: Aniline ($\text{C}_6\text{H}_5\text{NH}_2$).
2. Step (i): Reaction with $\text{Br}_2 \text{ (excess)}, \text{H}_2\text{O}$
   • The amino group ($-\text{NH}_2$) is strongly activating, and in aqueous medium, it undergoes electrophilic aromatic substitution to form 2,4,6-tribromoaniline (contains $3$ Br atoms).
3. Step (ii): Reaction with $\text{NaNO}_2, \text{HCl}, 273\text{ K}$
   • Diazotization converts the $-\text{NH}_2$ group to a diazonium salt, yielding 2,4,6-tribromobenzenediazonium chloride.
4. Step (iii): Reaction with $\text{CuCN/KCN}$
   • Sandmeyer reaction replaces the diazonium group ($-\text{N}_2^+$) with a cyano group ($-\text{CN}$), forming 2,4,6-tribromobenzonitrile.
5. Step (iv): Reaction with $\text{H}_3\text{O}^+, \Delta$
   • Acid hydrolysis converts the cyano group ($-\text{CN}$) into a carboxylic acid group ($-\text{COOH}$), yielding 2,4,6-tribromobenzoic acid.
6. Step (v): Reaction with $\text{SOCl}_2, \text{pyridine}$
   • Chlorination converts the carboxylic acid into an acyl chloride, yielding 2,4,6-tribromobenzoyl chloride as the major product $Q$.

Number of $\text{Br}$ atoms in compound $Q = 3$

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Scheme 2: Synthesis of Compound $S$

1. Reactant $R$: Benzene ($\text{C}_6\text{H}_6$).
2. Step (i): Reaction with $\text{Oleum}$
   • Sulfonation yields benzenesulfonic acid ($\text{C}_6\text{H}_5\text{SO}_3\text{H}$).
3. Steps (ii) & (iii): Reaction with $\text{NaOH}, \Delta$ followed by $\text{H}^+$
   • Alkali fusion followed by acidification converts benzenesulfonic acid to phenol ($\text{C}_6\text{H}_5\text{OH}$).
4. Step (iv): Reaction with $\text{Br}_2, \text{CS}_2, 273\text{ K}$
   • Electrophilic bromination of phenol in a non-polar solvent ($\text{CS}_2$) at low temperature selectively yields 4-bromophenol (para-bromophenol) as the major product $S$.

Number of $\text{Br}$ atoms in compound $S = 1$

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Scheme 3: Synthesis of Compound $T$

1. Step (i): Reaction of $S$ (4-bromophenol) with $\text{NaOH}$
   • Deprotonation forms sodium 4-bromophenoxide.
2. Step (ii): Reaction of sodium 4-bromophenoxide with $Q$ (2,4,6-tribromobenzoyl chloride)
   • Nucleophilic acyl substitution results in the formation of an ester, 4-bromophenyl 2,4,6-tribromobenzoate as the major product $T$.

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Conclusion:

Compound $T$ consists of:

• $3$ bromine atoms from the 2,4,6-tribromobenzoyl moiety ($Q$)
• $1$ bromine atom from the 4-bromophenoxy moiety ($S$)

$\text{Total number of Br atoms in } T = 3 + 1 = 4$