Sat March 05, 2011 By:

How would you diffrentiate between SN1 and SN2 mechanisms of substitution reactions? give one example of each?

Expert Reply
Sun March 06, 2011
Dear student
 SN2, reaction : CH3Cl + NaOH = CH3OH + NaCl  proof it follows kinetics of second-order and where possible, shows retention of configuration.On the other hand, SN1 reactions take place in two steps not one(difference from SN2). Example - (CH3)3CCl/ NaOH/H2O = (CH3)3C+ (Cation)
 .This is step one called ionisation step. The next step is union between this cation and OH- ion.
 The kinetics is of first order : Rate = K[RX], where R = (CH3)3CCl. Also where possible, inversion of configuration takes place not retention.
Examples: 2-Chlorobutane + NaOH gives a pure stereomer of 2-Pentanol, in SN2 way but
R1R2R3CCl +NaOH gives a recimic mixture of R1R2R3COH in SN1 mechanism.
Dear Student

We hope that clarifies your query.

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