Advanced Stereochemistry — DU B.Sc (hons) Chemistry Previous Year Question Papers

4. (a) Assign Re and Si faces of acetaldehyde and explain how a nucleophile attacks each face. (b) Are all chiral centres stereogenic centres? Is the reverse true? Explain with suitable examples. (8,7) 5. (a) Explain Cram's rule with its limitations, with suitable two examples. (b) Explain the application of CD in stereochemistry. 6. (a) Explain the following terms with examples : (b) Explain the stereochemistry and configuration in Spiro compounds. (8,7) hit_ructions for CandidaLtry 1. (a) Indicate the simple axes of symmetry present in the following molecules : (iii) benzene (b) Arrange the atoms and groups with increasing priority -CH,CH, - NO, -CH,Br, -COOH, -CH,OH, 2. (a) What do you mean by asymmetric and dissymmetric molecules? Give two examples. (b) What are the most common features, which makes a compound chiral? (c) Explain the most stable confirmation of cyclohexane. (7,4,4) 3. Assign the absolute configuration of the following optically active compounds.