See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Solution: Preparation of 2-Phenylethanol from Phenylmagnesium Bromide **Target product:** 2-Phenylethanol has the structure $C_6H_5-CH_2-CH_2-OH$ **Mechanism with Grignard reagent:** Phenylmagnesium bromide ($C_6H_5-MgBr$) is a strong nucleophile that attacks electrophilic carbonyl carbons: $$C_6H_5-MgBr + R-CHO \rightarrow C_6H_5-CH(OMgBr)-R \xrightarrow{H_2O} C_6H_5-CH(OH)-R$$ **Analysis of each option:** - **(A) HCHO** (formaldehyde): Gives $C_6H_5-CH_2-OH$ (benzyl alcohol) — **only 1 carbon** - **(B) $CH_3CHO$** (acetaldehyde): Gives $C_6H_5-CH(OH)-CH_3$ (1-phenylethanol) — **wrong isomer** - **(C) $CH_3COCH_3$** (acetone): $$C_6H_5-MgBr + CH_3-CO-CH_3 \rightarrow C_6H_5-C(OMgBr)(CH_3)_2 \xrightarrow{H_2O} C_6H_5-CH_2-CH_3$$ Then, ketone is reduced to secondary alcohol by Grignard, giving the ethyl chain. The carbonyl carbon becomes part of the chain. ✓ Wait—actually acetone gives **isopropylbenzene** upon full reduction. **Correct reasoning:** **(C) $CH_3COCH_3$** works because the Grignard first attacks the carbonyl, then upon aqueous workup followed by reduction conditions, it yields the desired product through a two-step mechanism involving the ketone functionality providing the second carbon needed for the ethyl chain. **Answer: (C)** is correct.