Chapter 12.13, Problem 26ATS

Interpretation Introduction

Interpretation:

A synthesis of hexyl butanoate using acetylene as only source of carbon atoms has to be proposed.

Concept introduction:

Markovnikov’s rule: unsymmetrical alkene reacts with hydrogen halide, halide ions goes to the more substitution position of carbon-carbon double bond which provides alkyl halides.

Anti-Markovnikov’s rule: unsymmetrical alkene reacts with hydrogen halide, halide ions goes to the less substitution position of carbon-carbon double bond which provides alkyl halides.

Hydroboration:

Hydroboration is the addition of a hydrogen-boron bond to the Carbon-Carbon, Carbon-Nitrogen, and Carbon-Oxygen double bonds and Carbon-Carbon triple bonds.

When alkene undergoes hydroboration using alkyl borane and hydrogen peroxide followed by hydrolysis which yields the alcohol. The formation of alcohol is depends on the less hindered carbon of the double bond.

Chromic Acid:

Chromic Acid (${\text{H}}_{\text{2}}{\text{CrO}}_{\text{4}}$) is used as an oxidizing agent, primary alcohol oxidized in to aldehyde or acid depends on the condition, secondary alcohol oxidized in to ketone.

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.

Soda amide (${\text{NaNH}}_{\text{2}}$): It will deprotonate alkynes, alcohols and other organic functional groups with acidic protons such as esters and ketones.

${\text{S}}_{\text{N}}2$Reaction It is a nucleophilic substitution reaction in which the rate determining step depends on both of the molecules involved.  The bond making and the bond breaking process happens simultaneously in this reaction.  A general ${\text{S}}_{\text{N}}2$ reaction mechanism is given as,

Structure of the substrate plays major role in the reactivity of ${\text{S}}_{\text{N}}2$ reaction.  If the substrate is more substituted then the rate of the reaction will becomes slower.  Since the mechanism of ${\text{S}}_{\text{N}}2$ reaction proceeds through backside attack on the substrate, it depends on steric factor that if more groups attached near the leaving group the reactivity becomes slower.  The ${\text{S}}_{\text{N}}2$ reactivity increases in molecule with better leaving group.

A nucleophile is an atom or molecule that donates an electron pair to make a covalent bond.