The photolysis of the arylnitramines.

The limited published work on the photolysis of the arylnitramines has shown that the predominant process is the fission of the N-NO2 bond. In non-substituted nitramines, the nitro group attacks the ring, but in heavily substituted nitramines, this group is lost to the system. A study of the photolysis of phenylnitramine, using all the available energy from a medium pressure mercury arc, shows that at room temperature the reaction is complex. Radiation is shown to have a similar effect. By filtering out all energy of wavelength lower than 3130A., the reaction is simplified slightly. At low temperatures, the only products of the reaction are the isomeric 2- and 4-nitroanilines. Under no conditions is 3-nitroaniline formed. Kinetic studies have been carried out at temperatures between 20° and -40°. These show that the reaction approximates to first order kinetics. Theoretical considerations show that zero order, or first order kinetics are possible, depending on the concentration of the nitramine; it is also shown that these ideal states cannot be attained, since the products of the reaction absorb energy in the same region as the nitramine. The decomposition is shown to be an intermolecular reaction, and a mechanism is proposed to account for the non-formation of the 3-nitroaniline. A second primary process is tentatively proposed to account for the observed formation of a compound which appeared to be an intermediate between the nitramine and the nitroaniline. Nuclear magnetic resonance studies show that phenylnitramine does not exist in tautomeric equilibrium under neutral, anhydrous conditions. The ultraviolet and infrared spectra of certain arylnitramines have been recorded. The photolysis of n-amylnitramine indicates that ring-closure may be possible by the irradiation of suitable aliphatic nitramines.