Please use this identifier to cite or link to this item: http://hdl.handle.net/10316/101239
Title: UV-Induced Photochemistry of 1,3-Benzoxazole, 2-Isocyanophenol, and 2-Cyanophenol Isolated in Low-Temperature Ar Matrixes
Authors: Reva, Igor 
Jesus, A. J. Lopes 
Nunes, Cláudio M 
Roque, José P L
Fausto, Rui 
Issue Date: 2021
Publisher: American Chemical Society
Project: info:eu-repo/grantAgreement/POCI-01-0145-FEDER-028973/PT 
info:eu-repo/grantAgreement/FCT/UIDB/00313/2020 
info:eu-repo/grantAgreement/FCT/UIDP/00313/2020 
UIDB/EQU/00102/2020 
UIDP/EQU/00102/2020 
Serial title, monograph or event: The Journal of Organic Chemistry
Volume: 86
Issue: 9
Abstract: The monomers of 1,3-benzoxazole isolated in a cryogenic argon matrix were characterized by infrared spectroscopy. The photochemistry of matrix-isolated 1,3-benzoxazole, induced by excitation with a frequency-tunable narrowband UV light, was investigated. Irradiation at 233 nm resulted in a nearly quantitative conversion of 1,3-benzoxazole into 2-isocyanophenol. The individual photochemical behavior of the in situ produced 2-isocyanophenol was studied upon excitations at 290 nm, where 1,3-benzoxazole does not react. The photochemistry of isomeric matrix-isolated 2-cyanophenol was also studied. The photoreactions of 2-substituted (cyano- or isocyano-) phenols were found to have many similarities: (i) OH bond cleavage, yielding a 2-substituted (cyano- or isocyano-) phenoxyl radical and an H-atom, (ii) recombination of the detached H-atom, resulting in an oxo tautomer, and (iii) decomposition leading to fulvenone, together with HCN and HNC. In another photoprocess, 2-cyanophenol undergoes a [1,5] H-shift from the hydroxyl group to the cyano group yielding isomeric ketenimine. The analogous [1,5] H-shift from the hydroxyl group to the isocyano group must have also occurred in 2-isocyanophenol; however, the resulting nitrile ylide isomer is kinetically unstable and collapses to benzoxazole. All photoproducts were characterized by comparing their observed infrared spectra with those computed at the B3LYP/6-311++G(d,p) level. The mechanistic analysis of the photochemistry occurring in the family of the title compounds is presented.
URI: http://hdl.handle.net/10316/101239
ISSN: 0022-3263
1520-6904
DOI: 10.1021/acs.joc.0c02970
Rights: embargoedAccess
Appears in Collections:I&D CQC - Artigos em Revistas Internacionais

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