Q.How will you convert benzaldehyde into the following compounds?

Step 1. (i) TO BENZOPHENONE: benzaldehyde + C6H5MgBr (dry ether), then H3O+ work-up, undergoes nucleophilic addition of the Grignard's phenyl carbanion to the aldehyde's carbonyl carbon, giving a SECONDARY alcohol (an aldehyde + RMgX always gives a secondary alcohol): diphenylmethanol, C6H5-CH(OH)-C6H5. This secondary alcohol is then oxidised (K2Cr2O7/H+, PCC, or CrO3) to the ketone: benzophenone, C6H5-CO-C6H5.

Step 2. (ii) TO BENZOIC ACID: benzaldehyde is simply oxidised directly with an oxidising agent such as acidified K2Cr2O7 or alkaline/acidic KMnO4 (Section 12.5.B.1) to give benzoic acid, C6H5-COOH, in one step -- no Grignard step is needed here, since the aldehyde's own C-H is oxidised straight to -COOH. …

Match each target functional-group change to the named reaction that produces it: a ketone from an aldehyde needs Grignard addition (to a secondary alcohol) THEN oxidation; a same-carbon acid from an aldehyde needs direct oxida …

• Trying to oxidise benzaldehyde directly to benzophenone -- oxidation of an aldehyde only ever adds an oxygen to give the SAME-carbon-count acid (Section 12.5.B.1); reaching a ketone with an EXTRA phenyl group requires …