Alkyl halides undergo reactions with brønsted-lowry bases. a is a sp² hybridized and trigonal planar and contains a vacant p orbital. all sn2 reactions proceed with attack of the nucleophile, resulting in of configuration at a stereognic center. spreading out charge by the overlap of an empty p orbital with an adjacent σ bond is called . equilibrium favors the products of nucleophilic substitution when the leaving group is a base than the nucleophile. according the to hammond postulate, the stability of the determines the rate of its formation. the formation of equal amounts of two enantiomeric products from a single starting material is called . a is an electron-rich compound, which donates a pair of electrons to an electron deficient compound, forming a covalent bond.