RELATIVE BASICITIES OF SOME ENDO AND EXO NORBORNYLAMINES

A series of endo- and exo-norbornylamines were synthesized and their r elative basicities determined in acetonitrile and dimethylformamide so lvents. The exo isomer is always more basic than the corresponding end o isomer in either solvent. All of the bicyclic amines studied have hi gher pK(a)'s in acetonitrile solvent than in dimethylformamide except for the 2-morpholinonorbornanes which are just the reverse. This effec t is explained by the ability of the morpholine group to disperse a po sitive charge and the relative polarizabilities of the solvents. Semie mpirical AM1 and PM3 methods along with ab initio HF/STO-3G, HF/3-21G , and HF/6-31G methods were used to calculate proton affinities and d ipole moments for each of the amines. The results of the theoretical c alculations correspond well with the experimental observations.