Concept explainers
(a)
Interpretation:
The given reaction whether undergoes E1 or E2 elimination has to be predicted. Major product of the reaction has to be drawn.
Concept Introduction:
- Elimination reaction is a reaction in which an atom or group of a molecule is eliminated and a double bond is formed.
- This type of reaction primarily occur in alkyl/aryl halides.
- Elimination reactions are of two types – E1 elimination and E2 elimination.
- E1 elimination involves formation of carbocation by dissociation of
alkyl halide in one step. In next step removal of base by proton takes place. - E2 elimination is a concerted reaction and involves formation of transition state in which both proton and halide are removed in one single step.
- E2 elimination follows Zaistev’s rule that the major product is usually the most substituted
alkene . Thus E2 reaction is regioselective. If the leaving group is too weak then least substituted alkene is formed. - Primary and secondary halides undergo E2 elimination whereas tertiary halides undergo E1 elimination as tertiary carbocation formed is more stable.
- Allylic and benzylic halides undergo both E1 and E2 reactions.
- Presence of high concentration of strong base favours E2 reaction.
- Presence of weak base favours E1 reaction.
(b)
Interpretation:
The given reaction whether undergoes E1 or E2 elimination has to be predicted. Major product of the reaction has to be drawn.
Concept Introduction:
- Elimination reaction is a reaction in which an atom or group of a molecule is eliminated and a double bond is formed.
- This type of reaction primarily occur in alkyl/aryl halides.
- Elimination reactions are of two types – E1 elimination and E2 elimination.
- E1 elimination involves formation of carbocation by dissociation of alkyl halide in one step. In next step removal of base by proton takes place.
- E2 elimination is a concerted reaction and involves formation of transition state in which both proton and halide are removed in one single step.
- E2 elimination follows Zaistev’s rule that the major product is usually the most substituted alkene.
- Primary and secondary halides undergo E2 elimination whereas tertiary halides undergo E1 elimination as tertiary carbocation formed is more stable.
- Allylic and benzylic halides undergo both E1 and E2 reactions.
- Presence of high concentration of strong base favours E2 reaction.
- Presence of weak base favours E1 reaction.
(c)
Interpretation:
The given reaction whether undergoes E1 or E2 elimination has to be predicted. Major product of the reaction has to be drawn.
Concept Introduction:
- Elimination reaction is a reaction in which an atom or group of a molecule is eliminated and a double bond is formed.
- This type of reaction primarily occur in alkyl/aryl halides.
- Elimination reactions are of two types – E1 elimination and E2 elimination.
- E1 elimination involves formation of carbocation by dissociation of alkyl halide in one step. In next step removal of base by proton takes place.
- E2 elimination is a concerted reaction and involves formation of transition state in which both proton and halide are removed in one single step.
- E2 elimination follows Zaistev’s rule that the major product is usually the most substituted alkene.
- Primary and secondary halides undergo E2 elimination whereas tertiary halides undergo E1 elimination as tertiary carbocation formed is more stable.
- Allylic and benzylic halides undergo both E1 and E2 reactions.
- Presence of high concentration of strong base favours E2 reaction.
- Presence of weak base favours E1 reaction.
(d)
Interpretation:
The given reaction whether undergoes E1 or E2 elimination has to be predicted. Major product of the reaction has to be drawn.
Concept Introduction:
- Elimination reaction is a reaction in which an atom or group of a molecule is eliminated and a double bond is formed.
- This type of reaction primarily occur in alkyl/aryl halides.
- Elimination reactions are of two types – E1 elimination and E2 elimination.
- E1 elimination involves formation of carbocation by dissociation of alkyl halide in one step. In next step removal of base by proton takes place.
- E2 elimination is a concerted reaction and involves formation of transition state in which both proton and halide are removed in one single step.
- E2 elimination follows Zaistev’s rule that the major product is usually the most substituted alkene.
- Primary and secondary halides undergo E2 elimination whereas tertiary halides undergo E1 elimination as tertiary carbocation formed is more stable.
- Allylic and benzylic halides undergo both E1 and E2 reactions.
- Presence of high concentration of strong base favours E2 reaction.
- Presence of weak base favours E1 reaction.
(e)
Interpretation:
The given reaction whether undergoes E1 or E2 elimination has to be predicted. Major product of the reaction has to be drawn.
Concept Introduction:
- Elimination reaction is a reaction in which an atom or group of a molecule is eliminated and a double bond is formed.
- This type of reaction primarily occur in alkyl/aryl halides.
- Elimination reactions are of two types – E1 elimination and E2 elimination.
- E1 elimination involves formation of carbocation by dissociation of alkyl halide in one step. In next step removal of base by proton takes place.
- E2 elimination is a concerted reaction and involves formation of transition state in which both proton and halide are removed in one single step.
- E2 elimination follows Zaistev’s rule that the major product is usually the most substituted alkene.
- Primary and secondary halides undergo E2 elimination whereas tertiary halides undergo E1 elimination as tertiary carbocation formed is more stable.
- Allylic and benzylic halides undergo both E1 and E2 reactions.
- Presence of high concentration of strong base favours E2 reaction.
- Presence of weak base favours E1 reaction.
(f)
Interpretation:
The given reaction whether undergoes E1 or E2 elimination has to be predicted. Major product of the reaction has to be drawn.
Concept Introduction:
- Elimination reaction is a reaction in which an atom or group of a molecule is eliminated and a double bond is formed.
- This type of reaction primarily occur in alkyl/aryl halides.
- Elimination reactions are of two types – E1 elimination and E2 elimination.
- E1 elimination involves formation of carbocation by dissociation of alkyl halide in one step. In next step removal of base by proton takes place.
- E2 elimination is a concerted reaction and involves formation of transition state in which both proton and halide are removed in one single step.
- E2 elimination follows Zaistev’s rule that the major product is usually the most substituted alkene.
- Primary and secondary halides undergo E2 elimination whereas tertiary halides undergo E1 elimination as tertiary carbocation formed is more stable.
- Allylic and benzylic halides undergo both E1 and E2 reactions.
- Presence of high concentration of strong base favours E2 reaction.
- Presence of weak base favours E1 reaction.
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