what is SN1 and SN2 reaction give details.
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haracteristics of SN¹ reactions: -
Two step reaction.Rate of reaction = K [R — L]It is a first order reaction.Carbocation intermediate is formed. rearrangement of carbocation is possible.Rate is dependent on stability of carbocation. [3°>2°>1°]Rate of reaction also depends on stability of cation and anion.Polar Protic Solvent favours SN¹ reaction. (As PPS dissolves both cation and anion in it)Leaving group should be strong i.e. weak base (same as SN²).Weak nucleophile performs SN¹ reaction. (Strong nucleophile will directly attack substrate resulting in E¹ reaction)Rate of reaction is independent of concentration and strength of nucleophile.Products formed will be both R- and S- form i.e. mirror image.Low temperature favours SN¹ reactions.
Characteristics of SN² reactions: -
Single step reaction.Rate of reaction = K [R — L] [Nu(:)]It is a second order reaction.Rate is dependent on concentration and strength of Nucleophile.Transition state is formed which is sp² hybridized, planar structure. (Not sp³d as Carbon doesn't have d orbital.)No carbocation intermediate formation.Leaving group should be strong i.e. weak base.Rate of reaction is inversely proportional to bulkiness of groups attached to C atom. [CH3Cl > CH3CH2Cl > CH3CH(CH3)Cl > CH3C(CH3)²Cl]Rate of reaction 1° > 2° > 3° substrates.Strong nucleophile performs SN² reactions. Nucleophile attacks substrate directly from backside.Polar Aprotic Solvent like DMSO, DMF, DMA favours SN² reactions. (Because PAS doesn't dissolves/solvent cations and it dissolves only anions in solution, so by taking PAS cations are removed and only Nu(:) is only anion present to attack substrate.]Walden inversion occurs.Reaction is favored by low temperature. High temperature leads to E² reaction.
Two step reaction.Rate of reaction = K [R — L]It is a first order reaction.Carbocation intermediate is formed. rearrangement of carbocation is possible.Rate is dependent on stability of carbocation. [3°>2°>1°]Rate of reaction also depends on stability of cation and anion.Polar Protic Solvent favours SN¹ reaction. (As PPS dissolves both cation and anion in it)Leaving group should be strong i.e. weak base (same as SN²).Weak nucleophile performs SN¹ reaction. (Strong nucleophile will directly attack substrate resulting in E¹ reaction)Rate of reaction is independent of concentration and strength of nucleophile.Products formed will be both R- and S- form i.e. mirror image.Low temperature favours SN¹ reactions.
Characteristics of SN² reactions: -
Single step reaction.Rate of reaction = K [R — L] [Nu(:)]It is a second order reaction.Rate is dependent on concentration and strength of Nucleophile.Transition state is formed which is sp² hybridized, planar structure. (Not sp³d as Carbon doesn't have d orbital.)No carbocation intermediate formation.Leaving group should be strong i.e. weak base.Rate of reaction is inversely proportional to bulkiness of groups attached to C atom. [CH3Cl > CH3CH2Cl > CH3CH(CH3)Cl > CH3C(CH3)²Cl]Rate of reaction 1° > 2° > 3° substrates.Strong nucleophile performs SN² reactions. Nucleophile attacks substrate directly from backside.Polar Aprotic Solvent like DMSO, DMF, DMA favours SN² reactions. (Because PAS doesn't dissolves/solvent cations and it dissolves only anions in solution, so by taking PAS cations are removed and only Nu(:) is only anion present to attack substrate.]Walden inversion occurs.Reaction is favored by low temperature. High temperature leads to E² reaction.
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Answer:
Explanation:
SN1 reaction :-
Substrate affect the rate of reaction.
It involve only 1 Step.
Two intermediate state is there.
Weak nucleuophile.
Carbocation stability.
For completing reaction elimination, rearrangement.
SN2 reaction :-
Substrate and necluophile affect the rate of reaction.
It involve only 2 Step.
One intermediate state is there.
Strong nucleuophile.
Steric hindrance.
For completing reaction elimination
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