Synthesis and Identification of Amino Acid T

To determine the identity of compound T, we trace the reaction sequence step by step starting from compound O:

1. Oxidation of Compound O to Compound P: Compound O is $1,2$-dipropylbenzene (an ortho-dialkylbenzene). Vigorous oxidation of $1,2$-dipropylbenzene using acidic potassium permanganate ($\text{KMnO}_4/\text{H}^+$) cleaves the alkyl side-chains at the benzylic position to yield phthalic acid (benzene-$1,2$-dicarboxylic acid) as compound P: $\text{\textbf{O}} \,(1,2\text{-dipropylbenzene}) \xrightarrow{\text{KMnO}_4/\text{H}^+} \text{\textbf{P}} \,(\text{Phthalic acid})$

2. Formation of Compound Q: Reaction of phthalic acid (P) with ammonia ($\text{NH}_3$) followed by heating gives phthalamide (Q): $\text{\textbf{P}} \,(\text{Phthalic acid}) \xrightarrow[\Delta]{\text{NH}_3} \text{\textbf{Q}} \,(\text{Phthalamide})$

3. Formation of Compound S: Strong heating of phthalamide (Q) results in the elimination of a molecule of ammonia ($\text{NH}_3$), leading to cyclization and formation of phthalimide (S): $\text{\textbf{Q}} \,(\text{Phthalamide}) \xrightarrow{\text{Strong Heating}} \text{\textbf{S}} \,(\text{Phthalimide}) + \text{NH}_3\uparrow$

4. Gabriel Phthalimide Synthesis to form Compound T: Phthalimide (S) undergoes a Gabriel synthesis reaction:

   • Treatment with $\text{KOH}$ deprotonates the imide nitrogen to form potassium phthalimide: $\text{Phthalimide} + \text{KOH} \rightarrow \text{Potassium phthalimide} + \text{H}_2\text{O}$
   • Potassium phthalimide undergoes an $\text{S}_\text{N}2$ nucleophilic substitution reaction with ethyl $2$-bromopropanoate ($\text{CH}_3\text{CH(Br)COOCH}_2\text{CH}_3$) to yield $N$-(1-ethoxycarbonylethyl)phthalimide.
   • Subsequent acidic hydrolysis (acidification) cleaves the amide linkage and hydrolyzes the ethyl ester group, releasing phthalic acid and the $\alpha$-amino acid alanine ($\text{CH}_3\text{-CH(NH}_2\text{)-COOH}$): $\text{\textbf{S}} \xrightarrow{(1)\,\text{KOH}, \; (2)\,\text{CH}_3\text{CH(Br)COOCH}_2\text{CH}_3, \; (3)\,\text{H}_3\text{O}^+} \text{\textbf{T}} \,(\text{Alanine})$

Thus, compound T is alanine.

Correct Option: B