Functional Group Organic Chemistry-I — DU B.Sc. (Prog.) Applied Physical Science with Analytical Methods in Chemistry & Biochemistry Previous Year Question Papers

1. Give explanation for the following : (i) How will you prepare chlorobenzene by Sandmeyer reaction? Write the reaction steps. (ii) Write the chemical reaction of acetone with semicarbazide. (iii) Compare the acidic strength of alcohols and phenols? Give reason. (iv) How can you prepare the following compounds from the given alkyl halide (a) Nitrite and (v) Write the mechanism of Williamson ether synthesis. (3×5) 2. (i) An unknown organic compound (A) gives H2 on reacting with sodium metal? It also gives Iodoform test and forms an aldehyde on oxidation with acidic potassium dichromate. The molecular formula of the formed aldehyde is C2H4O. Name the compound(A) and give the equations of these reactions. (ii) Vinyl halides do not undergo SN1 and SN2 reaction. Explain the reason behind this. (iii) What is the directive effect of –OH group on the aromatic ring in phenol? Write the bromination reaction of phenol step by step. (5,5,5) 3. (i) Why are aldehydes more reactive than ketones towards nucleophilic addition reactions? (ii) Write the mechanism of Pinacol-Pinacolone rearrangement. (iii) Give the mechanism of SN1 reactions in alkyl halide. Arrange the following alkyl halides in decreasing order of reactivity towards SN1 reaction. 4. (i) Give the product of the following reaction with step-by-step mechanism. Write the name of the reaction: (ii) How will you prepare 2-methylpropan-2-ol and propan-2-ol from Grignard reagent? (ii) Arrange the following phenols in decreasing order of acidity. Give reason. 5. Write short note on any three of the following : (1) Aldol condensation (ii) Clemmensen reduction (iv) Wittig reaction (5,5,5) 6. Complete the following reactions and write the products of the reaction : Xylene, boil