Kinetics of the aminolysis and hydrolysis of alkyl nitrites: Evidence for an orbital controlled mechanism

The kinetics of the nitrosation of piperidine by propyl, iso-propyl, butyl, iso-butyl, sec-butyl, and tert-butyl nitrites in 0.1 M NaOH and of the hydrolysis of the nitrite esters were studied spectrophotometrically by monitoring the absorbance of the nitrites at 381 nm. The observed correlation between log k(2) and sigma* (rho* = 4.5) shows the reaction to proceed via electrophilic attack by the nitrites; the existence of an isokinetic relationship suggests a single mechanism for the whole series. Comparison of the relative reactivities of the alkyl nitrites (primary > secondary > tertiary) with characteristic parameters of their R groups (vertical ionization potentials and heats of formation of R(+)) suggests that these reactions are orbital controlled. All hydrolysis reactions were slower than the corresponding aminolysis reactions. This is attributed to a retardation of the former reaction by unfavourable interactions between the lone pairs of the nucleophile and the nitroso nitrogen atom.