Halogenoalkanes can undergo substitution reactions with potassium hydroxide solution.

State an equation for the reaction of ${\mathrm{C}}_4{\mathrm{H}}_9\mathrm{Cl}$ with $\mathrm{KOH}$.

Synthetic organic chemists often use a method referred to as retro-synthesis. Starting with knowledge of the structure and properties of the target compound, they think “in reverse” to determine possible synthetic pathways to produce it. Imagination, intuition, and reasoning all play their part in scientific innovation. Imagination transcends the limitations of acquired knowledge and opens up the possibility of new ideas.

What are the roles of these ways of thinking in solving synthetic pathway problems? Is retro synthesis a combination of understanding and imagination?

Substitution reactions may occur by either of two mechanisms namely ${\mathrm{S}}_{\mathrm{N}}1$ or ${\mathrm{S}}_{\mathrm{N}}2$. Outline the meaning of the term ${\mathrm{S}}_{\mathrm{N}}1$.

Predict the mechanism $\left({\mathrm{S}}_{\mathrm{N}}1 \mathrm{or} {\mathrm{S}}_{\mathrm{N}}2\right)$ expected for the reaction of the following halogenoalkanes with aqueous $\mathrm{KOH}$.

• 1-chlorobutane to form butan-1-ol
• 2-chloro-2-methylpropane to form 2-methylpropan-2-ol.

Explain the mechanism of each of the following reactions using curly arrows to represent the movement of electron pairs.

• 1-chlorobutane to form butan-1-ol
• 2-chloro-2-methylpropane to form 2-methylpropan-2-ol.

${\mathrm{C}}_5{\mathrm{H}}_{11}\mathrm{Br}+\mathrm{NaOH}\to {\mathrm{C}}_5{\mathrm{H}}_{11}\mathrm{OH}+\mathrm{NaBr}$

The reaction with 2-bromo-2-methylbutane proceeds by an ${\mathrm{S}}_{\mathrm{N}}1$ mechanism. Describe this mechanism using structural formulas and curly arrows to represent the movement of electron pairs.

Explain whether the boiling point of 1-bromopentane will be higher, lower, or the same as that of 2-bromo-2- methylbutane.

${\mathrm{C}}_5{\mathrm{H}}_{11}\mathrm{Br}+\mathrm{NaOH}\to {\mathrm{C}}_5{\mathrm{H}}_{11}\mathrm{OH}+\mathrm{NaBr}$

The product ${\mathrm{C}}_5{\mathrm{H}}_{11}\mathrm{OH}$ formed from the reaction with 1-bromopentane is warmed with ethanoic acid in the presence of a few drops of concentrated sulphuric acid. State the name of the type of reaction taking place and the structural formula of the organic product.

Deduce a multi-step synthesis for each of the following conversion. For each step state the structural formulae of the reactants and products and the conditions used for the reactions.

Propene to propyl ethanoate (2 steps)