Accession Number : AD0634651

Title :   LIGHT ATTENUATION BY PHOTOCHEMICAL MEANS: PHOTOCHROMISM,

Corporate Author : ARMY NATICK LABS MASS

Personal Author(s) : Weinstein, Julius ; bluhm,Aaron L. ; Langmuir,Margaret E. ; Strom,E. Thomas

Report Date : JUN 1966

Pagination or Media Count : 14

Abstract : It was found that the photochromism of 2-(2,4-dinitrobenzyl)pyridine is not limited to this compound, but is the common property of a class of aromatic nitro compounds which possesses certain structural characteristics: the presence of a nitro and a methenyl group ortho to each other. Solvents were found to have a marked effect on the rate of the fading reactions; As were substituents in the para position of the aromatic ring of o-nitrobenzylpyridines. It was found that on irradiation with ultraviolet light, 3,3'-dinitro-4,4'-di(2-pyridylmethyl)azoxybenzene undergoes simultaneously aci-nitro tautomerization and geometrical isomerization. A new class of photochromic nitro compounds was discovered. The essential structural requirement for photochromism in these 1-aryl-2-nitroalkenes is that the nitro and phenyl groups bear a cis relationship with respect to each other. It was shown that some of the simpler o-nitrobenzyl compounds, such as o-nitroluene, are not only photochromic, but give relatively stable free radicals when irradiated with ultraviolet light. These radicals were identified as phenyl nitroxides. (Author)

Descriptors :   (*PHOTOCHROMISM, CHEMISTRY), (*ORGANIC NITROGEN COMPOUNDS, PHOTOCHROMISM), NITROBENZENES, PYRIDINES, MOLECULAR STRUCTURE, REACTION KINETICS, THERMOCHEMISTRY, AROMATIC COMPOUNDS, MOLECULAR ISOMERISM, FREE RADICALS, PHOTOCHEMICAL REACTIONS

Subject Categories : Radiation and Nuclear Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE