Question

NO SPAM...OTHERWISE HE/SHE WILL BE REPORTED TO THE MODERATOR ....How to know wheather the reaction is SN1 or SN2 ??..EXPLAIN .

Answer 1

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SN1 REACTION:- it is Uni molecular first order reaction
molecularity =1
order of reaction=1
this reaction complete in two step
in this reaction Carbo cation obtained as a intermediate and reaction of alkyl halides towards SN1 reaction depends upon stability of carbocation

order:- 3°alkyl halide> 2°alkyl halide>1°alkyl halide

in this reaction rearrangement is possible because carbon cation can rearrange itself

nucleophile main attack from the front as well as from the back side of Carbo cation
if alkyl halide is optically active then due to attack of nucleophile retention plus inversion both take place but inversion take place in greatest amount so partial recimisation take place
it is favoured by weak nucleophile like water alcohol etc. and this reaction is favoured by polar protic solvent like HCL alcohol water Acetic Acid etc.

SN2 REACTION:- it is bimolecular second order reaction
molecularity =2
order of reaction =2

this reaction completes in single step and no reaction intermediate obtained only transition state is developed reactivity of alkyl halides towards SN2 reaction only depends on steric factor greater the steric factor lesser the reactivity towards SN2 reaction

order:- 1°alkyl halide> 2°alkyl halide>3°alkyl halide

in this reaction rearrangement is not possible because No carbo cation is obtained

nucleophile can attack only from the back side of carbon from alkyl halide and in this reaction complete inversion (weldone inversion) take place

it is favoured by strong nucleophile and high concentration of nucleophile like NAOH

it is favoured by polar aprotic solvents Nike like Ether acetone dimethylformamide etc.

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Answer 2

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$\huge\green{SN1 Mechanism }$

Stands for unimolecular nucleophilic substitution reaction .

Followed by tertiary alkyl halides

Complete in two steps .

Follows first order kinetics .

These have polar solvent

$\huge\orange{SN2 Mechanism }$

Stands for bimolecular nucleophilic substitution reaction .

Followed by Primary alkylhalides .

Complete in one Step .

These have non polar solvent



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So ......


These knowing these we will be able to find out whether reaction is SN1 or SN2

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