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Upstream product

• 833-50-1 2-phenylbenzo[d]oxazole 

Downstream Products

• 833-50-1 2-phenylbenzo[d]oxazole 

Relevant academic research and scientific papers

Photodehalogenation and Photodimerization of 2-(4-Halophenyl)benzoxazoles. Dependence of the Mechanism on the Nature of the Halogen Atom

Irradiation of oxygen-free solutions of 2-(4-halophenyl)benzoxazoles at 300 nm led to dimerization or dehalogenation reactions.The fluoro derivative formed only dimer, while the chloro compound underwent both dimerization and dehalogenation.The bromo and iodo compounds did not form dimers but were dehalogenated.Fluorescence studies showed that the intersystem crossing yield decreased from the fluoro to the iodo compound.While dimerization was found to involve a singlet state, the excited state responsible for photodehalogenation of the bromo and iodo compounds was found to be the triplet on the basis of quenching and sensitization experiments.Triplet excited-state lifetimes were estimated.Photodehalogenation of 2-(4-chlorophenyl)benzoxazole occurs via the singlet state, involving an excimer as demonstrated from the influence of concentration on quantum yield.Photodehalogenation of the chloro and bromo compounds was considerably enhanced in the presence of electron donors such as cis-piperylene and triethylamine.These dehalogenation reactions are believed to proceed via an excited charge-transfer complex.

Photochemical Behavior of 2-Phenylbenzoxazole. Synthesis of 1,3-Diazetidine via the Intermolecular ? + 2?> Cycloaddition of Two Carbon-Nitrogen Double Bonds

The photochemical behavior of 2-phenylbenzoxazole (1) in cyclohexane solutions is investigated.In concentrated solutions, photodimerization of 2-phenylbenzoxazole is observed (Φ 0.08).In dilute solutions, this reaction is no longer efficient, and only a very slow reaction with cyclohexane takes place, leading to photoaddition and photosubstitution products with a low quantum yield (Φ -3).Photosensitization and quenching experiments as well as heavy-atom effects indicated that the two reactions derive from different excited states.The photodimerizatio n occurs from the singlet excited state and the reaction with the solvent from the triplet state.Photodimer 2 is stable in the solid state at room temperature but reverts to 1 quantitatively in solution.The rate of the cycloreversion reaction can be enhanced either by catalysis or by irradiation.The activation barrier determined by UV measurements was found to be 90 kJ mol-1.By use of microcalorimetric experiments, the molar enthalpy of reversion was found to be -116 kJ mol-1.For application of this new system to light energy conversion, the recycling capacity of the interconvertion process as well as the heterogeneous catalysis of the thermal reversion was studied.

Cycloaddition of Two C=N Double Bonds. First Structural Evidence for Head-to-tail Photodimerization in the 2-Penylbenzoxazole Series

Irradiation of 2-(4-fluorophenyl)benzoxazole in a two-phase medium leads to crystals of the photoadduct; the head-to-tail structure of this dimer has been demonstrated by an X-ray study.