Identify X1 to X6

1. X1 is Toluene. Reaction with HNO2 (likely a typo for HNO3/H2SO4) leads to nitration, forming X2 (e.g., 4-nitrotoluene). 2. X2 undergoes reduction to form X3 (e.g., 4-aminotoluene). 3. X3 reacts with Cl to form X4 (e.g., 4-chloro-N-methylaniline). 4. X4 reacts with NH3Cl to form X5 (e.g., N-methyl-4-chloroaniline). 5. X5 reacts with KOH (p-p) to form X6 (e.g., N-methyl-4-chlorophenol).