Triethyloxonium tetrafluoroborate, (CH3CH2)3O+BF4 -, is a solid with melting point 91–92 °C. Show how this reagent can transfer an ethyl group to a nucleophile (Nuc:-)in an SN2 reaction. What is the leaving group? Why might this reagent be preferred to an ethyl halide? (Consult Table 6-2.)
Solution 67SP :
Here, we have to show how the reagent Triethyloxonium tetrafluoroborate can transfer an ethyl group to a nucleophile (Nuc:-)in an SN2 reaction and we have to identify which is the leaving group and state the reason for preferring the above reagent to an ethyl halide Consulting Table 6-2.
SN2 reaction is a substitution reaction involving a nucleophile where 2 species are involved in the slowest rate determining step. ‘SN’ stands for nucleophilic substitution and ‘2’ determines that the rate determining step is bimolecular. Rate determining step is a step in a multistep reaction, that controls the overall reaction rate.
In SN2 mechanism, the bond formation and bond breaking happens simultaneously, i.e the nucleophilic substitution to the reactant which forms bond and the leaving group from the reactant that breaks the bond when nucleophile is substituted, happen simultaneously.