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Vanadyl β-tetrabromoporphyrin: synthesis, crystal structure and its use as an efficient and selective catalyst for olefin epoxidation in aqueous medium
- Dar, Tawseef Ahmad, Tomar, Reshu, Mian, Rasel Mohammad, Sankar, Muniappan, Maurya, Mannar Ram
- RSC advances 2019 v.9 no.18 pp. 10405-10413
- Fourier transform infrared spectroscopy, X-ray diffraction, catalysts, catalytic activity, crystal structure, electrochemistry, electron paramagnetic resonance spectroscopy, epoxidation reactions, matrix-assisted laser desorption-ionization mass spectrometry, porphyrins, temperature, vanadyl ions
- We hereby report the synthesis, characterization and catalytic applications in the epoxidation of alkenes by a vanadyl porphyrin having bulky bromo substituents at the β-positions viz. vanandyltetrabromotetraphenylporphyrin (1). The synthesized porphyrin was characterized by various spectroscopic techniques like UV-visible, FT-IR, EPR, MALDI-TOF mass spectrometry and single crystal X-ray analysis. Porphyrin 1 has a nonplanar structure as indicated by its X-ray structure, DFT and electrochemical studies. 1 was analyzed for its catalytic application in the epoxidation of various alkenes. The catalytic reactions were carried out in CH₃CN/H₂O mixture in 3 : 1 (v/v) ratio. 1 displayed good efficiency in terms of mild reaction conditions, lower reaction temperature and minimal catalyst amount consumption. 1 exhibited excellent selectivity, high conversion efficiency and huge TOF (7600–9800 h⁻¹) in a significantly low reaction time of 0.5 h. Catalyst 1 was regenerated at the end of various catalytic cycles making it reusable and industrially important.