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Photogeneration of N-Heterocyclic Carbenes: Application in Photoinduced Ring-Opening Metathesis Polymerization
Published on: November 29, 2018
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Dual Photochemistry of Benzimidazole.
José P L Roque1, Mário T S Rosado1, Rui Fausto1
1CQC-IMS, Department of Chemistry, University of Coimbra, Coimbra 3004-535, Portugal.
The Journal of Organic Chemistry
|February 16, 2023
Summary
Benzimidazole photochemistry reveals two pathways: fixed-ring and ring-opening isomerizations. These reactions form new tautomers and isocyano-containing products, offering insights into molecular transformations.
Area of Science:
- Photochemistry
- Spectroscopy
- Quantum Chemistry
Background:
- Benzimidazole exists as 1H-tautomers in argon matrices at low temperatures.
- Understanding benzimidazole's photochemical behavior is crucial for related heterocyclic compounds.
Purpose of the Study:
- To investigate the photochemistry of matrix-isolated 1H-benzimidazole.
- To identify photoproducts and elucidate reaction pathways.
Main Methods:
- Matrix isolation at 15 K.
- Frequency-tunable narrowband UV excitation.
- Vibrational spectroscopy and natural bond orbital analysis.
Main Results:
- Observed formation of 4H- and 6H-tautomers and isocyano-containing products.
- Identified two primary reaction pathways: fixed-ring and ring-opening isomerizations.
- H-atom recombination with radicals occurs at positions of high spin density.
Conclusions:
- Benzimidazole photochemistry exhibits a dual pathway mechanism, distinct from indole and benzoxazole.
- The study provides a mechanistic understanding of H-atom transfer and radical recombination in benzimidazole photochemistry.
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