Theoretical Study of the Reaction Formalhydrazone with Singlet Oxygen. Fragmentation of the C=N Bond, Ene Reaction and Other Processes1. (2nd December 2013)

• Record Type: Journal Article
• Authors: Rudshteyn, Benjamin; Castillo, Álvaro; Ghogare, Ashwini A.; Liebman, Joel F.; Greer, Alexander
• Is Part Of: Photochemistry and photobiology. Volume 90:Number 2(2014:Mar./Apr.)
• Page Start: 431
• Page End: 438
• Publication Date: 2013-12-02
• Subjects: Photochemistry -- Periodicals; Light -- Physiological effect -- Periodicals; 541.35
• DOI: 10.1111/php.12199
• Languages: English
• ISSNs: 0031-8655

Abstract

<abstract abstract-type="main" id="php12199-abs-0001"> <title>Abstract</title> <p>Photobiologic and synthetic versatility of hydrazones has not yet been established with ¹O₂ as a route to commonly encountered nitrosamines. Thus, to determine whether the "parent" reaction of formalhydrazone and ¹O₂ leads to facile C=N bond cleavage and resulting nitrosamine formation, we have carried out CCSD(T)//DFT calculations and analyzed the energetics of the oxidation pathways. A [2 + 2] pathway occurs via diradicals and formation of 3‐amino‐1, 2, 3‐dioxazetidine in a 16 kcal/mol⁻¹ process. Reversible addition or physical quenching of ¹O₂ occurs either on the formalhydrazone carbon for triplet diradicals at 2–3 kcal mol⁻¹, or on the nitrogen (N(3)) atom forming zwitterions at ~15 kcal/mol⁻¹, although the quenching channel by charge‐transfer interaction was not computed. The computations also predict a facile conversion of formalhydrazone and ¹O₂ to hydroperoxymethyl diazene in a low‐barrier 'ene' process, but no 2‐amino‐oxaziridine‐<italic>O</italic>‐oxide (perepoxide‐like) intermediate was found. A Benson‐like analysis (group increment calculations) on the closed‐shell species are in accord with the quantum chemical results.</p> </abstract>