Functional Group 3

• Unsaturated or saturated compounds • Contain C-O-H single bonds • Oxygen is sp3 hybridised • Act as nucleophiles • Reactivity controlled by election rich oxygen atom. • Pka range = 15.5-8.0

Acidity decreases as alkyl substitution increases: positive inductive effect. - Alkyl groups are electron donating. Acidity increases with number of halogen substituents: negative inductive effect. - Halogens are electron withdrawing. PKa is dependent on the ability of neighbouring groups/substituents to stabilise (or destabilise) the resulting negative charge. E.g. Phenol is 100 more times more acidic than Cyclohexanol

• Similar increases in melting /boiling point across the homologous series. • Small alcohols are miscible with water, but solubility decreases as the size of the alkyl group increases.

• Hydration of alkenes • Hydrolysis of alkyl halides • Reduction of Carbonyl compounds

• Completely burns in O2 • React alcohol with sodium metal (leads to a redox reaction)

Two Step process within the body: 1) Alcohol dehydrogenase - Converts to aldehyde - OH->CHO 2) Aldehyde dehydrogenase - Converts to acid - CHO->COOH - All of which is carried out by enzymes.

• Because a nucleophile substitutes for the halogen these reactions are known as nucleophilic substitution pathways. S=Substitution N= Nucleophilic 1 = Only substrate is involved in the characteristics step (i.e. reaction is unimolecular). (First order) 2 = Both nucleophile and substrate are involved in the characteristic step (i.e. Reaction is bimolecular). (Second order)