Let's break down the synthesis of both compounds starting from **bromobenzene**. --- ## **(a) Synthesis of 2-Phenylacetaldehyde** ### **Target Structure** 2-Phenylacetaldehyde: **C₆H₅–CH₂–CHO** ### **Stepwise Solution** #### **Step 1: Formation of Benzyl Cyanide (Nitrile)** Convert bromobenzene to benzyl cyanide via a two-step process: 1. **Friedel–Crafts Alkylation** - **Reactants:** Bromobenzene, CH₂Cl₂, AlCl₃ - **Product:** Benzyl chloride (C₆H₅CH₂Cl) 2. **Nucleophilic Substitution** - **Reactants:** Benzyl chloride, NaCN - **Product:** Benzyl cyanide (C₆H₅CH₂CN) #### **Step 2: Reduction of Nitrile to Aldehyde** - **Reactant:** Benzyl cyanide (C₆H₅CH₂CN) - **Partial Reduction:** DIBAL-H (Diisobutylaluminum hydride) at low temperature - **Product:** 2-Phenylacetaldehyde (C₆H₅CH₂CHO) --- ### **Summary (a):** 1. **C₆H₅Br** → (**Friedel–Crafts + Alkyl halide formation**) → **C₆H₅CH₂Cl** 2. **C₆H₅CH₂Cl** + **NaCN** → **C₆H₅CH₂CN** 3. **C₆H₅CH₂CN** + **DIBAL-H** → **C₆H₅CH₂CHO** (2-Phenylacetaldehyde) --- ## **(b) Synthesis of 1,1-Diphenylpropan-1-ol** ### **Target Structure** 1,1-Diphenylpropan-1-ol: **C₆H₅–C(OH)(C₆H₅)–CH₂CH₃** ### **Stepwise Solution** #### **Step 1: Formation of Benzophenone** - **Friedel–Crafts Acylation** - **Reactants:** Bromobenzene, benzoyl chloride (C₆H₅COCl), AlCl₃ - **Product:** Benzophenone (C₆H₅COC₆H₅) #### **Step 2: Grignard Reaction** - **Preparation of Phenylmagnesium Bromide (Grignard Reagent):** - **Reactants:** Bromobenzene + Mg in dry ether → C₆H₅MgBr - **Alkylation:** - **Reactants:** Benzophenone + ethyl bromide (C₂H₅Br) in presence of C₆H₅MgBr - **Mechanism:** 1. Ethylmagnesium bromide (C₂H₅MgBr) attacks the carbonyl carbon of benzophenone. 2. Upon acidic workup, forms 1,1-diphenylpropan-1-ol. --- ### **Summary (b):** 1. **C₆H₅Br** → (**Mg, dry ether**) → **C₆H₅MgBr** 2. **C₆H₅MgBr** + **C₆H₅COCl** → **C₆H₅COC₆H₅** (Benzophenone) 3. **C₆H₅COC₆H₅** + **C₂H₅MgBr** → **1,1-diphenylpropan-1-ol (after acidic workup)** --- ## **Final Answers** ### **(a) Synthesis of 2-Phenylacetaldehyde** 1. **Bromobenzene** → **Benzyl chloride** (via Friedel–Crafts alkylation) 2. **Benzyl chloride** → **Benzyl cyanide** (via NaCN) 3. **Benzyl cyanide** → **2-Phenylacetaldehyde** (via DIBAL-H reduction) ### **(b) Synthesis of 1,1-Diphenylpropan-1-ol** 1. **Bromobenzene** → **Phenylmagnesium bromide** (Grignard reagent) 2. **Phenylmagnesium bromide** + **Benzoyl chloride** → **Benzophenone** 3. **Benzophenone** + **Ethylmagnesium bromide** → **1,1-diphenylpropan-1-ol** (after hydrolysis) --- ### **Reaction Schemes** #### **a)** ``` C6H5Br → [Friedel–Crafts] → C6H5CH2Cl → [NaCN] → C6H5CH2CN → [DIBAL-H] → C6H5CH2CHO ``` #### **b)** ``` C6H5Br → [Mg/ether] → C6H5MgBr 2C6H5MgBr + C2H5COCl → (C6H5)2CO (Benzophenone) (C6H5)2CO + C2H5MgBr → (C6H5)2C(OH)CH2CH3 ``` If you need detailed mechanisms or reagent conditions, let me know!