Butanal reacts with potassium cyanide, followed by dilute acid, to form 2-hydroxypentanenitrile.
Name the mechanism for the reaction between potassium cyanide and butanal.
The 2-hydroxypentanenitrile formed by the reaction is a mixture of equal amounts of two isomers.
2-Hydroxypentanenitrile can be used in the synthesis of the monomer, pent-2-enenitrile, CH3CH2CH=CHCN\text{CH}_3\text{CH}_2\text{CH}=\text{CHCN}CH3CH2CH=CHCN. Suggest a suitable reagent and conditions for this dehydration reaction.
Draw a section of the polymer poly(pent-2-enenitrile), showing three repeating units.