The structure and photolysis of some cyclic N-nitroso amines, oximes and amines

High temperature nuclear magnetic resonance spectroscopy was used to study the barrier to N-N bond rotation in seven cyclic N-nitroso amines. Arrhenius activation energies of 20.0±0.5 Kcal. mole-1 and 21.8±0.6 Kcal. mole-1 were calculated for N-nitrosoazacyclopentane and N-nitrosoazacyclohexane,respectively. The free energy of activation of hindered N-N bond rotation was calculated to be 24.5±0.1 Kcal. mole-1 for  N-nitrosocamphidine and >23-3 Kcal. mole-1 for N-nitrosoazacycloheptane, N-nitrosoazacyclooctane and N-nitroso-3-azabicyclo[3,2,2]nonane at the coalescence temperatures.The solution photolysis of N-nitrosoazacyclononane and N-nitrosocamphidine produced the parent amines and one amidoxime as the only isolated and positively identified photolysis products.The mass spectral fragmentation patterns of seven cyclic oximes were determined using metastable peaks and accurate mass measurements. Most emphasis was placed on the M-OH fragment formed by a McLafferty-type rearrangement and the M-NO and NO+ ions.The mass spectral fragmentation patterns of the oximes from cycloheptanone to cyclododecanone were found to be similar to the fragmentation patterns for cyclohexanone oxime.The mass spectral fragmentation patterns of several cyclic and bicyclic amines were found to be similar to the fragmentation patterns reported for azacyclohexane.