Mechanism, thermochemistry, and kinetics of formation of PhC(O)H and HOPhC(O)H during unimolecular decomposition of P-PhC(O)HPhOH.

Context: Bisphenols are one of the main components of bio-oil, produced during the pyrolysis of lignin-containing biomass. Synthetic bisphenols are used in polycarbonate plastics, epoxy resins, and thermal papers. Their mechanism of oxidation is important for the determination of the fire safety of these materials and the possibility of using them as additives in fuels for the decrease and description of ignition delays, as well as for the determination of their health risk assessment in medicine.

Mechanism of formation of p-benzylenephenol peroxide radical (p-PhC(O)HPhOH).

Context: The reactions of radicals with O play the important role in the biological, medicinal, and industrial processes. The mechanism of this reaction is studied previously for the alkane, alkene, alkyne, phenols, and close-related radicals. According to these studies, the formation of intermediates in these reactions is predicted only for the aromatic radicals.

Rate constants for the reactions between OH and perfluorinated alkenes.

The rate constants for the reactions of OH radicals with fully fluorinated alkenes containing different numbers of -CF(3) groups next to olefinic carbon, CF(2)═CF(2), CF(2)═CFCF(3), CF(3)CF═CFCF(3), and (CF(3))(2)C═CFC(2)F(5), were measured between 230 and 480 K using the flash photolysis resonance fluorescence technique to give the following expressions: k(C(2)F(4))(250-480 K) = 1.32 × 10(-12) × (T/298 K)(0.9) × exp(+600 K/T) cm(3) molecule(-1) s(-1), k(C(3)F(6))(230-480 K) = 9.

Disproportionation pathways of aqueous hyponitrite radicals (HN2O2(*)/N2O2(*-)).

Pulse radiolysis and flash photolysis are used to generate the hyponitrite radicals (HN2O2(*)/N2O2(*-)) by one-electron oxidation of the hyponitrite in aqueous solution. Although the radical decay conforms to simple second-order kinetics, its mechanism is complex, comprising a short chain of NO release-consumption steps. In the first, rate-determining step, two N2O2(*-) radicals disproportionate with the rate constant 2k = (8.

Determination of phosphate/arsenate by a modified molybdenum blue method and reduction of arsenate by S(2)O(4)(2-).

A modified molybdenum blue method for fast and accurate measurement of arsenate and phosphate in aqueous solution at concentrations below 10mumoll(-1) is reported. The modification consists of optimizing the composition of the molybdenum-containing solution (potassium antimony tartrate, ammonium molybdate, sulfuric acid). Selective reduction of arsenate by sodium dithionite is used to determine phosphate concentrations, and for the speciation of arsenate and arsenite, in an aqueous mixture according to the scheme developed by Johnston and Pilson.

Hydrogen cyanide exhaust emissions from in-use motor vehicles.

Motor vehicle exhaust emissions are known to contain hydrogen cyanide (HCN), but emission rate data are scarce and, in the case of idling vehicles, date back over 20 years. For the first time, vehicular HCN exhaust emissions from a modern, in-use fleet at idle have been measured. The 14 tested light duty motor vehicles were operating at idle as these conditions are associated with the highest risk exposure scenarios (i.

Rate constant for the reaction of OH with H2 between 200 and 480 K.

The rate constant for the reaction of OH radicals with molecular hydrogen was measured using the flash photolysis resonance-fluorescence technique over the temperature range of 200-479 K. The Arrhenius plot was found to exhibit a noticeable curvature. Careful examination of all possible systematic uncertainties indicates that this curvature is not due to experimental artifacts.

One-electron reduction of aqueous nitric oxide: a mechanistic revision.

The pulse radiolysis of aqueous NO has been reinvestigated, the variances with the prior studies are discussed, and a mechanistic revision is suggested. Both the hydrated electron and the hydrogen atom reduce NO to yield the ground-state triplet (3)NO(-) and singlet (1)HNO, respectively, which further react with NO to produce the N(2)O(2)(-) radical, albeit with the very different specific rates, k((3)NO(-) + NO) = (3.0 +/- 0.

Hyponitrite radical, a stable adduct of nitric oxide and nitroxyl.

All major properties of the aqueous hyponitrite radicals (ONNO- and ONNOH), the adducts of nitric oxide (NO) and nitroxyl (3NO- and 1HNO), are revised. In this work, the radicals are produced by oxidation of various hyponitrite species in the 2-14 pH range with the OH, N3, or SO4- radicals. The estimated rate constants with OH are 4 x 10(7), 4.