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Boaro A, Reis RA, Silva CS, Melo DU, Pinto AGGC, Bartoloni FH. Evidence for the Formation of 1,2-Dioxetane as a High-Energy Intermediate and Possible Chemiexcitation Pathways in the Chemiluminescence of Lophine Peroxides. J Org Chem 2021; 86:6633-6647. [PMID: 33876635 DOI: 10.1021/acs.joc.1c00230] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A kinetic study of the chemiluminescent (CL) reaction mechanism of lophine-derived hydroperoxides and silylperoxides induced by a base and fluoride, respectively, provided evidence for the formation of a 1,2-dioxetane as a high-energy intermediate (HEI) of this CL transformation. This was postulated using a linear Hammett relationship, consistent with the formation of negative charge on the transition state of HEI generation (ρ > 1). The decomposition of this HEI leads to chemiexcitation with overall low singlet excited state formation quantum yield (ΦS from 1.1 to 14.5 × 10-5 E mol-1); nonetheless, ΦS = 1.20 × 10-3 E mol-1 was observed with both peroxides substituted with bromine. The use of electron-donating substituents increases chemiexcitation efficiency, while it also reduces the rate for both formation and decomposition of the HEI. Different possible pathways for HEI decomposition and chemiexcitation are discussed in light of literature data from the perspective of the substituent effect. This system could be explored in the future for analytical and labeling purposes or for biological oxidation through chemiexcitation.
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Affiliation(s)
- Andreia Boaro
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Avenida dos Estados, 5001, Bloco A, Santo André, 09210-580 São Paulo, Brazil
| | - Roberta Albino Reis
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Avenida dos Estados, 5001, Bloco A, Santo André, 09210-580 São Paulo, Brazil
| | - Carolina Santana Silva
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Avenida dos Estados, 5001, Bloco A, Santo André, 09210-580 São Paulo, Brazil
| | - Diêgo Ulysses Melo
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Avenida dos Estados, 5001, Bloco A, Santo André, 09210-580 São Paulo, Brazil
| | | | - Fernando Heering Bartoloni
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Avenida dos Estados, 5001, Bloco A, Santo André, 09210-580 São Paulo, Brazil
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Soares AR, Reis RA, Melo DU, Boaro A, Bartoloni FH. Better late than never! Transition state character involved in the neutral solvolysis of an oxalic ester determined by the ionizing power of ethanol/water and methanol/water mixtures. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.113800] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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