AROMATIC NUCLEOPHILIC-SUBSTITUTION REACTI ON IN DIPOLE APROTIC-SOLVENTS .2. P-NITROHALOGENOBENZENES REACTIVITY DURING THE REACTION WITH POTASSIUM PHENOXIDE IN DIMETHYLPHORMAMIDE

Starting from second-order rate constants, experimentally derived for ''initial'' rates of potassium phenoxide and p-nitrohalogenobenzenes ( k(2)(obs)) measured for at least two different concentrations of potas sium phenoxide, the real second-order rate constants (k(2)(real)) for the reaction of ''free'' phenoxide (dissociated from ion pairs) and or ganic halide, were calculated. This procedure was applied for the seri es of p-nitrohalogenobenzenes (halogen = F, Cl, Br, I) and a sequence of reactivities F much greater than Br > Cl > I was established. The r eal values of the second-order rate constants - first reported here- w ere useful in deduction of the reaction mechanism that was proved to b e a typical SN2Ar one.