Both the C_(beta)-H and C_alpha-X bonds are breaking in the transition state of E2 reactions.The rate of E2 reactions is of second order.The rate shows primary isotopic (dueterium) effect. i.e. if C_beta-H is replaced by C_beta-D , the rate of reaction decreases sharply. The rate is also corelated with nucleofugality i.e. the ability of leaving group to leave.With a better nucleofuge, the rate of reaction increases.This is called he element effect. The element effect is also observed in E1cB reactions in which the second step is rate determining and elimination of first order w.r.t conjugate base is observed.For E1cB reaction K_H//K_D=1, therefore proton abstraction is not involved in the rate determing step In D_2O the incorporation of Deuterium at C_beta-H in the In E1 reaction only nucleofuge departs in slow step and a carbocation intermediate is formed. For the given compounds I and II the rate of elimination by EtO^(Theta)//EtOH shows K_H//K_D=7.1 What is the about this reaction

Both the C_(beta)-H and C_alpha-X bonds are breaking in the transition

1.	Both the C_(beta)-H and C_alpha-X bonds are breaking in the transition state of E2 reactions.The rate of E2 reactions is of second order.The rate shows primary isotopic (dueterium) effect. i.e. if C_beta-H is replaced by C_beta-D , the rate of reaction decreases sharply. The rate is also corelated with nucleofugality i.e. the ability of leaving group to leave.With a better nucleofuge, the rate of reaction increases.This is called he element effect. The element effect is also observed in E1cB reactions in which the second step is rate determining and elimination of first order w.r.t conjugate base is observed.For E1cB reaction K_H//K_D=1, therefore proton abstraction is not involved in the rate determing step In D_2O the incorporation of Deuterium at C_beta-H in the In E1 reaction only nucleofuge departs in slow step and a carbocation intermediate is formed. For the given compounds I and II the rate of elimination by EtO^(Theta)//EtOH shows K_H//K_D=7.1 What is the about this reaction
Answer» Both `C_(beta)-H` and `C_alpha-Br` bonds are BREAKING SIMULTANEOUSLY in transition state Only `Br^(Theta)` is eliminated in rate determining step Only `H^(Theta)` or `D^(o+)` is eliminated in rate determining step the reaction intermediate is resonance stabilized Solution :The breaking of `C_beta-H` is faster than `C_beta-D` and both `C_beta-H` and `C_alpha-Br` are breaking in same step. It is an E2 reaction.