Nucleophilic substitution, electrophilic addition and reaction pathways

Learning objectives

Define a nucleophile as an electron-rich species that donates a pair of electrons, and describe the nucleophilic substitution of a halogenoalkane by aqueous hydroxide ions to give an alcohol

(HL) Compare the SN1 and SN2 mechanisms using curly arrows to show the movement of electron pairs, and explain how the class of halogenoalkane, the leaving group, the nucleophile and the solvent determine which pathway operates and what happens to the configuration at the carbon atom

Define an electrophile as an electron-deficient species that accepts a pair of electrons, and describe the electrophilic addition of halogens, hydrogen halides and steam to alkenes, including the use of bromine water as a test for unsaturation

(HL) Deduce the mechanism of electrophilic addition to an unsymmetrical alkene using curly arrows, and apply the relative stability of primary, secondary and tertiary carbocations to predict the major product

(HL) Explain why benzene undergoes electrophilic substitution rather than addition, and outline the nitration of benzene, identifying the electrophile generated from concentrated nitric and sulfuric acids

(HL) Devise a multi-step synthetic route between two organic compounds, selecting reagents and conditions for substitution, addition, oxidation, reduction, esterification and the conversion of a nitrile or a nitro compound to an amine

(HL) Define a Lewis acid as an electron-pair acceptor and a Lewis base as an electron-pair donor, identify the coordination bond formed when they react, classify nucleophiles as Lewis bases and electrophiles as Lewis acids, and describe how ligands form complex ions with transition element cations