Chapter 3, Problem 71CP

(a)

Interpretation Introduction

Interpretation:

The most acidic proton in compound (1) has to be identified; the corresponding conjugate base of structure (2) has to be drawn and justified.

Concept Introduction:

Conjugate acid: Protonated Base that gets results is called conjugate acid of the given base.

In above reaction, the acid $\text{HA}$ donates proton ${\text{H}}^{+}$ and becomes ${\text{A}}^{-}$(is known as conjugate base).

Conjugate Base: Deprotonated Acid that gets results is called conjugate Base of the given Acid.

In above reaction, the base ${\text{A}}^{-}$ gets accepts proton ${\text{H}}^{+}$ and becomes $\text{HA}$ (is known as conjugate acid).

Flow of electron density: In the acid-base reaction, the flow of electron from high electron density to low density using curved arrow.

Curved arrows: Curved arrows are used to show the direction of electrons movement. It has a tail (the source of electrons, usually lone pair or bonding pair from a sigma or pi-bond) and head (the destination of electrons, usually forming new lone pair on atom or a new bond). Electrons always flow from high electron density to low electron density.

(b)

Interpretation Introduction

Interpretation:

Lithium diisopropyl amide (LDA) is an suitable base to deprotonate has to be justified using a quantitative argument based on ${\text{pK}}_{\text{a}}$ values.

Concept Introduction:

Using $p{K}_a$values to compare Acidity: In general, acid-base reaction said to reach equilibrium; the position of equilibrium is described by the term $K_{eq}$. When an acid-base reaction is carried out in aqueous solution, the new term arrives by the term $K_a$.

$p{K}_a=-log{K}_a$

$p{K}_a$ Values are used as measure of acidity; a strong acid will have a low $p{K}_a$ and a weak acid will have a high $p{K}_a$.

Using $p{K}_a$values to compare Basicity:  $p{K}_a$ Values are also used to compare bases; by drawing the conjugate acid of each base and compare the $p{K}_a$ values and identify the stronger base.

(c)

Interpretation Introduction

Interpretation:

Mechanism for the conversion of structure (1) to structure (2) has to be drawn.

Concept Introduction:

Flow of electron density: Curved arrow notation: In the acid-base reaction, the flow of electron from high electron density to low density using curved arrow.

Curved arrows: Curved arrows are used to show the direction of electrons movement. It has a tail (the source of electrons, usually lone pair or bonding pair from a sigma or pi-bond) and head (the destination of electrons, usually forming new lone pair on atom or a new bond). Electrons always flow from high electron density to low electron density.