116245-66-0Relevant academic research and scientific papers
The photochemical transformation and tautomeric composition of matrix isolated benzotriazole
Kiszka, Mariusz,Dunkin, Ian R.,Gebicki, Jerzy,Wang, Hong,Wirz, Jakob
, p. 2420 - 2426 (2007/10/03)
Photolysis of benzotriazole isolated in argon and nitrogen matrices at 12-14 K has been studied by means of UV-visible and IR absorption spectroscopy. Short wavelength irradiation resulted in N-NH bond scission to give diazoimine 3 and minor products: cyanocyclopentadiene 6 and ketenimine 5. The compound 3 was easily bleachable. With 420 nm light, the major pathway was cycloreversion to benzotriazole, but at shorter wavelengths photolysis of 3 led first to the ketenimine product and ultimately to cyanocyclopentadiene. The photoproducts were identified by means of their characteristic IR absorptions. Identification of 3 was additionally supported by comparison of experimental and computed IR transitions, which also indicated that 3 was generated predominantly as its E isomer. Detailed analysis of the benzotriazole IR spectra recorded prior to and after photolysis pointed towards the co-existence of both tautomeric forms, 1H-benzotriazole (1) and 2H-benzotriazole (2), frozen from the gas phase during matrix deposition. An estimate of 1.6:1 was obtained for the gas-phase [1H]:[2H] ratio at ca. 315 K, in fair agreement with another recent estimate. The benzotriazole tautomers exhibited different photoreactivity, but attempts to utilize this in identifying the IR bands of the individual tautomers were hampered by band overlap, and only a few unequivocal assignments could be made.
Photochemistry of (2-nitrophenyl)diazomethane studied by the matrix isolation technique. (Nitrophenyl)carbene to (carboxylphenyl)nitrene rearrangement by successive reduction of the nitro group with the carbenic center
Tomioka, Hideo,Ichikawa, Naoki,Komatsu, Kazunori
, p. 8045 - 8053 (2007/10/02)
Irradiation (λ > 350 nm) of (2-nitrophenyl)diazomethane (1) matrix-isolated in Ar at 10 K provided 2-nitrosobenzaldehyde (3) presumably as a result of intramolecular oxygen migration in (2-nitrophenyl)carbene (2). Upon further irradiation (λ > 350 nm), 3 was decomposed to give a mixture of 2,1-benzisoxazol-3(1H)-one (4) and carbonylcyclopentadiene imine (5) along with CO2. The oxazolone (4) underwent decarboxylation to give 5 upon irradiation with shorter wavelength light (λ > 300 nm) but not at longer wavelength (λ > 350 nm), suggesting 4 is not the direct precursor for 5 in the photolysis of 3. Irradiation (λ > 350 nm) of (4-n-butyl-2-nitrophenyl)diazomethane (1b) under similar conditions resulted in the formation of carbonyloximinocyclohexadienylidene (7) which then produced the oxazolone (4b) and the imine (5b) upon further irradiation, suggesting that a 1,4-biradical generated as a result of abstraction of H at the ortho position by the photoexcited nitroso group was involved in the reaction of 3 forming 4. (2-Carboxyphenyl)nitrene (9) generated by 1,4-OH shift in the 1,4-biradical was postulated as an intermediate leading to 5, and this was actually demonstrated by independent generation of 9 by the photolysis of 2-azidobenzoic acid (8).
