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Ma X, Anyaeche RO, Feng E, Johnson E, Roller E, Rumley DJ, Nash JJ, Kenttämaa HI. Gas-Phase Reactivity of Quinoline-Based Singlet Oxenium Cations. J Org Chem 2024; 89:5458-5468. [PMID: 38554096 DOI: 10.1021/acs.joc.3c02895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/01/2024]
Abstract
Isomeric quinolyloxenium cations were generated in the gas phase in an ion trap mass spectrometer to explore their reactions. The structures of some products were identified via collision-activated dissociation experiments involving model compounds to demonstrate that they have the expected heavy atom connectivity. The lack of radical reactions suggests that the cations have closed-shell singlet electronic ground states. Calculations (CASPT2/CASSCF(16,14)/cc-pVTZ//CASSCF(16,14)/cc-pVTZ) predict that their closed-shell singlet (1A') ground states are lower in energy by ca. 25 kcal mol-1 than their lowest-lying excited states. All cations are reactive toward dimethyl disulfide, dimethyl sulfide, and allyl iodide and most toward water and moderately reactive toward cyclohexane, reflecting their strongly electrophilic nature. They form adducts with nucleophiles in exothermic reactions (ca. 50 kcal mol-1 for dimethyl sulfide) that can fragment or be stabilized via IR emission. Most water adducts spontaneously isomerize to lower-energy tautomers. The nucleophiles preferentially add to those carbon atoms in the benzene ring that have the greatest positive charge (but not the carbonyl carbon). The cations react with cyclohexane via hydride abstraction by the oxygen atom. This is the only reaction that initially involves the oxygen atom and hence reflects the formally positively charged, monovalent oxygen atom in these cations.
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Affiliation(s)
- Xin Ma
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47906, United States
| | - Ruth O Anyaeche
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47906, United States
| | - Erlu Feng
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47906, United States
| | - Erynn Johnson
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47906, United States
| | - Ethan Roller
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47906, United States
| | - Daniel J Rumley
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47906, United States
| | - John J Nash
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47906, United States
| | - Hilkka I Kenttämaa
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47906, United States
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Gutowski Ł, Liszewska M, Bartosewicz B, Budner B, Weyher JL, Jankiewicz BJ. Investigation of organic monoradicals reactivity using surface-enhanced Raman spectroscopy. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2022; 278:121312. [PMID: 35537259 DOI: 10.1016/j.saa.2022.121312] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 03/28/2022] [Accepted: 04/23/2022] [Indexed: 06/14/2023]
Abstract
Surface-enhanced Raman spectroscopy (SERS) and self-assembled monolayer (SAM) approaches were used to investigate the reactions of organic monoradicals with methanol. An attempt was made to generate monoradicals from thiophenols and phenylmethanethiols substituted with bromine, iodine, and nitro groups by irradiation with UV light. Monolayers of radical precursors were deposited on SERS substrates, which were then immersed in methanol and irradiated for 1 and/or 3, 6, 12 and 24 h in a UV photochemical reactor. Pre- and postreaction SERS spectra were obtained by using a confocal Raman microscope and compared with the spectra of expected products of the radical reaction with methanol. Our studies have shown that the efficiency of monoradical generation is highly dependent on the chemical structure of the precursor. In addition, it is shown that both the SERS substrate and experimental conditions used strongly influence the obtained results.
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Affiliation(s)
- Łukasz Gutowski
- Institute of Optoelectronics, Military University of Technology, gen. Sylwestra Kaliskiego 2, 00-908 Warsaw, Poland.
| | - Malwina Liszewska
- Institute of Optoelectronics, Military University of Technology, gen. Sylwestra Kaliskiego 2, 00-908 Warsaw, Poland.
| | - Bartosz Bartosewicz
- Institute of Optoelectronics, Military University of Technology, gen. Sylwestra Kaliskiego 2, 00-908 Warsaw, Poland.
| | - Bogusław Budner
- Institute of Optoelectronics, Military University of Technology, gen. Sylwestra Kaliskiego 2, 00-908 Warsaw, Poland.
| | - Jan L Weyher
- Institute of High-Pressure Physics, Polish Academy of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland.
| | - Bartłomiej J Jankiewicz
- Institute of Optoelectronics, Military University of Technology, gen. Sylwestra Kaliskiego 2, 00-908 Warsaw, Poland.
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