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Formation of a Tunneling Product in the Photorearrangement of o ‐Nitrobenzaldehyde
Author(s) -
Gerbig Dennis,
Schreiner Peter R.
Publication year - 2017
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201705140
Subject(s) - ketene , chemistry , quantum tunnelling , reactivity (psychology) , matrix isolation , photochemistry , computational chemistry , molecule , medicinal chemistry , organic chemistry , materials science , optoelectronics , medicine , alternative medicine , pathology
The photochemical rearrangement of o ‐nitrobenzaldehyde to o ‐nitrosobenzoic acid, first reported in 1901, has been shown to proceed via a distinct ketene intermediate. In the course of matrix isolation experiments in various host materials at temperatures as low as 3 K, the ketene was re‐investigated in its electronic and vibrational ground states. It was shown that hitherto unreported H‐tunneling dominates its reactivity, with half‐lives of a few minutes. Unexpectedly, the tunneling product is different from o ‐nitrosobenzoic acid formed in the photoprocess: Once prepared by irradiation, the ketene spontaneously rearranges to an isoxazolone via an intriguing mechanism initiated by H‐tunneling. CCSD(T)/cc‐pVTZ computations reveal that this isoxazolone is neither thermodynamically nor kinetically favored under the experimental conditions, and that formation of this unique tunneling product constitutes a remarkable and new example of tunneling control.