Question

Draw the transition state for each reaction.

a.

b.

Short answer

Answer

a. Transition state of a.

b.Transition state of b.

Step-by-step solution

Step-by-Step SolutionStep 1: Transition State

In a concerted reaction mechanism, the transition state is a particular configuration of the reactant that has the highest potential energy.

The Transition state is an intermediate structure in which the bond to be broken and the new bond to be formed are represented with dashed lines in the transition state of the compound.

The old dashed bonds mean that the old bonds are partially broken, and the new dashed bonds mean that the new bonds are partly formed.

Charge on the transition state

For a reactant that contains a negative or a positive charge, the transition state of this reactant would contain partial charges of either one.

Transition State of the given compounds

a. As the O-H bond partially breaks, the hydrogen forms a new bond partially with ${}_{}{}^{-}\mathrm{NH}_2$. This gives the transition state of the reaction coordinates. In this structure, the O-H-N bonds are shown with dashed lines, and all these three atoms share a partial negative charge $\left({\mathrm{\delta }}^{-}\right)$density.

Transition state of a.

b. A C-H bond is breaking off from tertiary carbocation, and a new O-H bond is forming in${\mathrm{H}}_2\mathrm{O}$. Hence, the transition state consists of a molecule in which both the reactants are attached with dashed (partial) bonds.

Transition state of b.