38719-36-7

Upstream product

• 62-53-3 aniline 
• 134-81-6 benzil 

Relevant academic research and scientific papers

A kinetic study on the spin polarization switching of benzil in the presence of triethylamine

Dual spin polarization of CIDEP signal of radicals produced in benzil/triethylamine in the benzene system was investigated by the time-resolved ESR and transient absorption technique. CIDEP signals showed absorption or emission depending on the concentration of triethylamine. Emissive CIDEP signal was observed below 10-3 M of triethylamine, whereas absorptive signal was observed above 10-1 M. The dual CIDEP signal was explained by the triplet mechanism (TM) and the radical-triplet pair mechanism (RTPM); the absorptive polarized TM signal was generated from the reaction of free triplet benzil with triethylamine, whereas the emissive polarized CIDEP signal was generated through the interaction between triplet benzil and benzil ketyl radical produced from the benzil-triethylamine complex.

A laser flash photolysis study on the reaction mechanisms of benzil with various amines

Nanosecond laser photolysis experiments were performed to study the reaction mechanism (absolute reaction quantum yield (φr)) of benzil ketyl radicals produced from both free triplet benzil and ground state complexes. The reaction quantum yields of benzil ketyl radical from free triplet benzil (φrfree) were 0.31, 0.17, 0.13, 0.08, and ~ 0 for triethylamine, N,N-diethylaniline, diethylamine, N-ethylaniline, and aniline, respectively. φrfree depended strongly on the number of hydrogen atoms that can be abstracted by benzil. The reaction quantum yield of the complex formed in the ground state (φrcom) was unity for all amines used. The large quantum yield (φrcom=1) was explained by a calculated conformation of the ground state complex.

Diffusion of electrically neutral radicals and anion radicals created by photochemical reactions

Diffusion processes of the intermediate radicals created by the photochemical reactions of ketones in alcoholic solvents are investigated by using the transient grating (TG) method. The electrically neutral radicals and the anion radicals of acetophenone, benzaldehyde, xanthone, benzophenone and benzil were created selectively by controlling the concentration of sodium hydroxide (NaOH) in alcoholic solvents. The translational diffusion constants (D) of the anion radicals, the neutral radicals, and the parent stable molecules can be successfully measured under the same conditions by this method. It is found that both the neutral and anion radicals diffuse slower than the parent molecules. Values of D of the anion radicals, the neutral radicals and the parent molecules are compared in detail in wide ranges of solvent viscosities, solute sizes and temperatures. Under any conditions, D values of the charged radicals are similar to those of the neutral radicals. A possible origin of such a similarity is discussed in term of the intermolecular charge polarizabilities of the radicals.

Time-Resolved EPR Study on the Photochemical Reactions of Benzil

A time-resolved EPR (TREPR) study on the photochemical reactions of benzil in 2-propanol and benzene-triethylamine (TEA) mixed solvents is reported.The emissive signals observed in 2-propanol are assigned to the benzoyl and benzil ketyl radicals, and the absorptive one observed in benzene-TEA is assigned to the benzil anion radical.The reactions are considered to occur from higher excited triplet (Tn) states through two-photon processes in 2-propanol but from the lowest excited triplet state through a one-photon process in benzene-TEA.TREPR studies are supplemented by optical studies including measurements of transient absorptions, phosphorescence quenching, and fluorescence quenching, whose results support the conclusion drawn from the EPR results.Possible polarization mechanisms to produce emissive signals are considered in detail.It is shown that the direct T1 -> Tn excitation does not produce the inversion of the polarization regardless of the signs of the zero-field splitting of the T1 and Tn states.It is then concluded that the emissive signals are due to the reaction from Tn produced via the Sn -> Tn intersystem crossing process.It is also found that the rise of the chemically induced dynamic electron polarization signal of the ketyl radical in 2-propanol consists of fast and slow components.The time profile of the slow rise component strongly depends on the temperature, the concentration of benzil, the excitation laser power, and the oxygen addition.From the analysis of these dependences it is suggested that the free-pair radical-pair mechanism can account for the main features of the slow polarization.

Dual Spin Polarization of CIDEP in Benzil/Quencher Systems

Dual spin polarization of triplet benzil was investigated by the time-resolved ESR technique.Spin polarization of triplet benzil showed only absorption in rigid matrices at 77 K.However, the phase of CIDEP signals caused by the triplet mechanism showed absorption or emission depending on the concentration of quenchers at room temperature.Both polarizations were generated through a one-photon absorption process.Absorptive polarized radicals were produced from free benzil, whereas emissive polarized radicals were produced from benzil/quencher complex.