Identify the suitable reagent to carry out the following chemical transformation:

Step-by-step solution

The given reaction is the controlled oxidation of a primary alcohol (benzyl alcohol) to an aldehyde (benzaldehyde). PCC (Pyridinium chlorochromate) in anhydrous CH ₂ Cl ₂ is a mild oxidizing agent that selectively oxidizes primary alcohols to aldehydes without further oxidation to carboxylic acids. Strong oxidizing agents like H ₂ CrO ₄ and K ₂ Cr ₂ O ₇ will oxidize benzyl alcohol completely to benzoic acid. OsO ₄ is a reagent used for the syn-dihydroxylation of alkenes, not for oxidizing alcohols. Thus, PCC is the