4829622
| Question | Answer |
| Converting halogenoalkanes to nitriles | 1. Reagent - KCN, NaCN, CN 2. Reaction conditions - Reagent dissolved in alcohol, Heating under reflex 3. Reaction type - Nucleophilic substitution 4. Product - nitrile |
| Mechanism for nitrile formation | 5(i) C-halogen bond polar (ii) C significantly positively charged (iii) CN uses lone electron pair to datively bond to partially positive C atom (iv) Simultaneously C-halogen bond cleaves to maintain quadrivalency and stability |
| Converting primary halogenoalkanes and primary amines | 1. Reagent - Concentrated ammonia 2. Reaction conditions - Reagent dissolved in alcohol, heating in a sealed tube 3. Reaction type - Nucleophilic substitution 4. Product - primary amine |
| Mechanism for primary amine formation | 5(i) C-halogen bond polar (ii) C significantly positively charged (iii) NH3 uses lone electron pair to datively bond to partially positive C atom (iv) Simultaneously C-halogen bond cleaves to prevent octet rule violation as this would make the C structure unstable |
| Converting halogenoalkanes to alcohols | 1. Reagent - Concentrated aqueous NaOH 2. Reaction conditions - heating under reflux 3. Reaction type - Nucleophilic substitution/ Hydrolylsis 4. Product - alcohol |
| Mechanism for alcohol formation | 5(i) C- halogen bond polar (ii) C significantly positively charged (iii) OH uses lone electron pair to datively bond to partially positive C atom (iv) Simultaneously C-halogen bond cleaves to prevent the presence of 5 bonding electron pairs in the valency shell - this is unstable |
| Converting halogenoalkanes to alkenes | 1. Reagent - NaOH 2. Reaction conditions - Reagent dissolved in ethanol, heating 3. Reaction type - elimination/ dehydrohalogenation 4. Product - Alkene |
| Mechanism for alkene formation | 5(i) OH accepts H+ to form H2O. (ii)C-halogen bond breaks heterolytically, forming a Br- (iii)Loss of an H atom and a halogen atom from adjacent C atoms (iv) Double bond formation between the 2 C atoms to maintain quadrivalency |
| Formation of a range of product from a halogen and alkane | 1. Reagent - Any halogen 2. Reaction condition - presence of sunlight or UV radiation Reaction type - free radical substitution/ halogenation |
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