Chapter 20: Alcohols, Amines, and Alkyl Halides

All three functional groups are classified as Level 1, meaning the heteroatom-bearing carbon has a single attachment to oxygen, nitrogen, or a halogen. Alcohols and alkyl halides are categorized by the number of carbon substituents on the functional group carbon, while amines are classified based on the number of organic groups bonded to nitrogen. Spectroscopic identification relies on characteristic infrared stretches: broad O-H signals for alcohols, N-H stretches for amines with distinct patterns for primary, secondary, and tertiary forms, and isotope patterns for halogenated compounds. Nuclear magnetic resonance spectroscopy reveals proton environments and spin-spin coupling following the n+1 rule, while rapid proton exchange of O-H and N-H groups produces broad signals confirmed through deuterium exchange. Alkyl halides undergo nucleophilic substitution via two competing mechanisms: the bimolecular SN2 pathway produces inverted stereochemistry and predominates with methyl and primary substrates due to minimal steric effects, while the unimolecular SN1 mechanism proceeds through a planar carbocation intermediate and occurs preferentially with tertiary substrates, yielding racemic products. Elimination reactions forming alkenes compete with substitution and follow Zaitsev's rule. Alcohols exhibit elevated boiling points from hydrogen bonding and are synthesized primarily through carbonyl reduction using reducing agents of varying strength. Their reactions include weak acid behavior with alkali metals, ether formation through the Williamson synthesis, and selective oxidation where primary alcohols form aldehydes or carboxylic acids and secondary alcohols yield ketones. Amines function as nucleophiles and Lewis bases through their nitrogen lone pair, though aryl and amide variants show reduced basicity from lone pair delocalization. Amine reactions include alkylation with alkyl halides to form quaternary ammonium salts and acylation with acid chlorides to produce amides.