Chapter 12, Problem 76CP

(a)

Interpretation Introduction

Interpretation:

A passible mechanism for given process has to be drawn.

Concept introduction:

Protonation means the addition of a proton ${\text{(H}}^{\text{+}}\text{ion)}$ to an atom or molecule forming the conjugate acid.

Bromination:  Any which introduces a bromine atom into a compound that is called bromination.

A carbocation is molecule having a carbon atom bearing three bonds and a positive formal charge.

(b)

Interpretation Introduction

Interpretation:

An efficient synthesis of 5, 9, 12, 16-tetramethyleicosane has to be proposed from using A, B and C as only source of carbon.

Concept introduction:

Lindlar reduction: The alkenes or alkynes can be reduced to alkanes with ${\text{H}}_{\text{2}}$ in the presence of metal catalyst $\left(\text{Pd}\right)$.  This heterogeneous catalyst that consists of palladium deposited on calcium carbonate which is then poisoned with various forms of lead or Sulphur.  The new $\text{C-H σ}$ bonds are formed simultaneously from $\text{H}$ atoms absorbed into the metal surface.

Protonation means the addition of a proton ${\text{(H}}^{\text{+}}\text{ion)}$ to an atom or molecule forming the conjugate acid.

Bromination:  Any which introduces a bromine atom into a compound that is called bromination.

Generally, the Grignard reagent reacts with the appropriate aldehyde or ketone $\left({\text{CH}}_{\text{3}}\text{CHO}\right)\text{,}$ followed by a water workup that result in formation of alcohol.