Chapter 17, Problem 17.1P

Interpretation Introduction

Interpretation:

The complete, detailed mechanism is to be drawn and the product for the reaction of $\text{3-methylbutanal}$ is to be predicted.

Concept introduction:

In nucleophilic addition reaction mechanism, a nucleophile tends to form a bond with the atom at the positive end of a polar p bond. The nucleophile is relatively electron rich, and the partially positive $\text{(δ1)}$ atom of the $\text{π}$ bond is relatively electron poor.

Answer to Problem 17.1P

The complete, detailed mechanism and product for the reaction of $\text{3-methylbutanal}$ is:

Explanation of Solution

The given reaction is:

KCN is ionic, so it dissolves in water as ${\text{K}}^{\text{+}}$ and ${\text{CN}}^{\text{-}}$ ions. ${\text{CN}}^{\text{-}}$ has a localized negative charge on C and is a strong nucleophile that will subsequently attack the electron-poor carbonyl carbon, breaking the $\text{π}$ bond of the double bond. The resulting ${\text{O}}^{\text{-}}$ is then protonated by the acid, producing a cyanohydrin, which is characterized by CN and OH groups bonded to the same C atom. The complete, detailed mechanism and product for the reaction of $\text{3-methylbutanal}$ is:

Conclusion

The complete, detailed mechanism and product for the reaction of $\text{3-methylbutanal}$ is determined on the basis of nucleophilic addition reaction.