Chapter 21.4, Problem BQ

Interpretation Introduction

Interpretation:

The relative ${\text{pK}}_{\text{a}}$ value of phenol in Capsaicin has to be chosen among the given options.

Concept introduction:

The ${\text{pK}}_{\text{a}}$ value of any acid increase, the acidity of the acid is decreases. Moreover electron withdrawing group is increase the acidity, the ${\text{pK}}_{\text{a}}$ value decrease.  Electron donating group is increase the ${\text{pK}}_{\text{a}}$ value, but decrease the acidity.