IGNOU CHE-06 - Organic Reaction Mechanism

1. a) Which of the carbocation is more stable in the following pairs and why? b) Explain the following: i) Enol form does not react with water to give diol. ii) Fluorine and iodine generally do not react with alkene or alkyne. iii) Hydroboration looks like an anti-Markownikowf’s addition. 2. Explain the following: a) Electron withdrawing substituents at the carbonyl carbon increases the reactivity towards nucleophilic addition reactions. b) Reaction of hydrocyanic acid and benzaldehyde is very slow, but become fast when cyanide ion is added. 3. a) Explain isotope effect in E2 elimination reaction with suitable example. b) Differentiate Saytzeff and Hofmann rules giving suitable examples. 4. a) State oxidation state. Calculate the oxidation state of carbon atom of CCl4. b) Predict the product(s) and give the mechanism of the following reactions: 5. Write short note on the following: (Give mechanism) a) Aldol condensation b) Michael addition 6. Write the chemical reaction for the following reactions along with their detail description: a) Reimer-Tiemann reaction b) Carbylamine reaction c) Wittig reaction d) Wolf rearrangement 7. a) Explain, why the reaction of m-bromoanisole with sodamide gives only one product. b) Describe the bromination reaction at alkylic and benzylic position by N-bromosuccinimide. 8. a) Write detail mechanism for the following rearrangements: i) Wagner-Meerwein rearrangement ii) Backmann rearrangement b) Explain the mechanism of [4+2] cycloaddition. 9. a) Taking suitable examples, explain the role of sensitisers in photo reactions. b) Describe reaction types used to construct a carbon skeleton with suitable examples. 10. Write short notes on: a) Cleaning action of soaps b) Auxochromes c) Antibiotics d) Condensation polymers e) Retrosynthesis