Phototransformations of Phenols in Aqueous Solutions under Different Excitation Modes

The photolysis of aqueous solutions of two widespread environmental organic ecotoxicants—phenol and 4-chlorophenol—on excitation by UV radiation from a KrCl exciplex laser and a glow-discharge KrCl excilplex lamp was studied. The irradiated solutions were studied by spectroscopic techniques. The laser and lamp photolyses were compared.     

Triplet states of humic acids studied by laser flash photolysis using different excitation wavelengths

The spectra and kinetics of short-lived intermediates formed from aqueous (0.1 N NaOH) solutions of the natural mixture of humic and fulvic acids (HFA) were studied by laser flash photolysis using excitation wavelengths of 337, 390, 470, and 520 nm. Laser photolysis of HFA with light of 520 and 470 nm results in the formation of triplet excited states (T_HFA) characterized by the broad absorption spectrum with a maximum near 630 nm and lifetimes of 0.15 ms in deoxygenated solutions. The formation of two types of T_HFA with lifetimes of 0.1 and 2 ms and absorption spectra with maxima at 570 nm is observed under photolysis with light of 337 and 390 nm. The estimation of quantum yields of T_HFA gives 1 and 0.3% under photolysis with excitation wavelengths of 337 and 520 nm, respectively. The rate constants of T_HFA quenching by molecular oxygen are equal to (7—8)·10⁸ L mol^–1 s^–1.     

C-Acylation of Electron-Excess Heterocycles by Isocyanatophosphoric Acid Dichlorides

Abstract

Isocyanatophosphoric acid dichlondes was used for introduction of phosphorus-containing groups at electron-excess heterocycles. Hetaryl containing dichlorophosphates, convenient starting material for synthesis for wide set of derivatives, were prepared by C-acylation with this reagent.     

C-Phosphorylation of Electron-Rich Heterocycles

Abstract

C-phosphorylation of pyrrole, furan, thiophene derivatives and their benzanalogs by phosphorus tribromide has been studied. Perspective methods for involving trivalent phosphorus residues at a different position of the rings have been developed. Unknown early the heterocycle's derivatives with tri- and tetracoordinated phosphorus substituents (1–5) and novel types of phosphoruscontaining heterocycles (6,7) have been obtained.     

Reactions of isocyanatophosphoryl difluoride with π-abundant nitrogen heterocycles and carbonyl compounds

Reactions of electron-rich nitrogen heterocycles with isocyanatophosphoryl difluoride were studied. Novel heteroylaminophosphoryl difluorides were obtained in high yields. N-Phosphorylated imines were synthesized for the first time from carbonyl compounds and phosphorus isocyanates. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 564–566, March, 2006.     

Fluorescent analysis of photoinduced biodegradation of cresol isomers

We have used fluorescence spectroscopy to study photoinduced biodegradation of ortho-cresol, para-cresol and mixture of them in water when excited by different UV radiation sources. We show that the efficiency of photolysis for both the individual isomers and the mixture of cresols is higher for excitation by radiation at λ ∼ 222 nm. Pre-irradiation of aqueous cresol solutions slows down subsequent biodegradation. Using a combination of UV irradiation and the strain Penicillium tardum H-2 for utilization of the cresol mixture led to complete degradation of para-cresol and partial degradation of ortho-cresol. Spectral and chromatographic study of the qualitative composition of the metabolites formed during biodegradation of para-cresol showed that preparatory metabolism of such compounds occurs both through oxidation of the methyl group with formation of 4-hydroxybenzoic acid and through hydroxylation with formation of 4-methylcatechol. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 2, pp. 250–255, March–April, 2008.     

Photolysis of Phenol and para-Chlorophenol by UV Laser Excitation

The photolysis of phenol and para-chlorophenol by irradiation with the fourth harmonic of a neodymium laser was examined using electronic absorption spectroscopy, fluorescence, and quantum-chemical techniques. It was found that the introduction of a chlorine atom into the phenol molecule increases the efficiency of photolysis of para-chlorophenol by excitation in the long-wavelength absorption band. The O–H and C–Cl bonds in the test compounds are ruptured via a predissociation mechanism in triplet states localized at the breaking bonds.     

Quantum yields of oxazines and phenoxazines and the investigation of their spectral luminescence properties in binary mixtures

The electronic spectra of Nile Blue acetate, phenoxazines, and its fluorinated analogs have been investigated experimentally and theoretically. The spectral-luminescence properties of these molecules have been studied in detail in ethanol and in nonpolar solvents (toluyl, dimethylsulfoxide) with an alcohol admixture (propanol, butanol, and isobutyl alcohol). The role of micelle formation in non-aqueous solvent on the spectral-luminescence of these molecules is elucidated. Also considered in this paper is the dependence of the quantum fluorescence yield of several oxazines and phenoxazines in ethanol on the structure of the dye molecules.B. D. Kuznetsov Siberian Physicotechnical Scientific-Research Institute at the State University, Tomsk, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 88–93, May, 1992.     

Molecular structure of dibenzoadamantylphosphonyl-17-crown-6 in the crystalline state and in solutions

Conclusions It has been shown that for dibenzoadamantylphosphonyl-17-crown-6 in the crystalline state and in solutions, the characteristic conformation has separate orientations of the unshared electron pairs of the oxygen atom, owing to the presence of the bulky adamantyl grouping.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2028–2036, September, 1984.