The radiation chemistry of aqueous benzene solutions has been studied by the electron-pulse radiolysis technique. Ultraviolet absorption spectra of some of the transient species have been recorded by synchronized flash-absorption spectroscopy. The elementary reactions occurring have been observed by fast photoelectric recording of the transient optical density. A transient spectrum having a broad absorption with a strong maximum at 313 mμ has been observed. On the basis of both spectrographic and kinetic evidence this spectrum is assigned to the hydroxycyclohexadienyl radical, (OH)C6H6·. The molar extinction coefficient is estimated to be ε3130=3500±800 M—1cm—1. A number of substituted cyclohexadienyl radicals have been observed in aqueous solution as well as in pure benzene and chloro-benzene. A second transient observed in oxygenated aqueous benzene solution shows an absorption shifted to lower wavelengths. This is attributed to the hydroxycyclohexadienyl peroxy radical, (OH)C6H6O2·. Absolute rate constants have been determined at 23°C for the following reactions: OH+C6H6=(OH)C6H6·(4.3±0.9)×109 M−1sec−1,OH+C6D6=(OH)C6D6·(4.7±0.9)×109 M−1sec−1,(OH)C6H6·+O2=(OH)C6H6O2·(5.0±0.6)×108 M−1sec−1. The yield of phenol in oxygenated solution was found to decrease continuously with increasing pulse intensity. At the highest intensity used, G(C6H5OH) = 0.19 molecules/100 ev. At the lowest pulse intensity used, G(C6H5OH) = 1.9 molecules/100 ev, which approaches the values found in steady irradiations. Some additional phenol is formed in slow post-irradiation reactions. Diphenyl was identified as a product in the deaerated system by gas chromatographic analysis. Its formation is largely the result of post-irradiation reactions, the initial yield being substantially lower than previously reported. The mechanism of the radiation chemical reaction in both deaerated and oxygenated solutions is discussed on the basis of the conclusion that the hydroxyl radical enters the ring to form the hydroxycyclohexadienyl radical.

Relationships among cellular structure, fracturability, and sensory properties in porous, brittle extrudates were investigated. Corn‐based extrudates intentionally processed to exhibit a range of physical structures were characterized in terms of cell size distribution, bulk density, mechanical strength, fracturability, and sensory attributes. These measurements show both mechanical strength, defined by average compressive stress during extended deformation, and fracturability, quantified by fractal and Fourier analyses of stress‐strain functions, increasing with either decreasing mean cell size or increasing bulk density. Fracturability parameters or structural characteristics are furthermore correlated with sensory scores for crunchiness, crispness, hardness and perceived density. These results indicate that cellularity strongly influences the pattern of mechanical failure and that failure characteristics, such as fractal dimension or power spectrum of stress‐strain functions, are reflective of sensory texture.

The one-electron reduction of pentacyanonitrosylferrate(II) ion, Fe(CN)5N02~(nitroprusside ion), in aqueous solution has been studied using continuous and pulse radiolysis techniques, the latter with optical absorption and kinetic conductivity detection. The reducing radicals eaq~, C02~, • 2 , (CH3)2ÓOH, and H react with Fe(CN)5N02™ (k = 1.0 X 10m, 4.0 X 10s, 6.7 X 108, 2.9 X 109, and 7 X 107 M™1 s™1, respectively) to yield Fe(CN)5N03~c haracterized by an absorption spectrum with Xmax 345 and 440 nm (emal 3.5 X 103 and 5.5 x 102 M4 cm™1, respectively); the spectrum is independent of pH (1-8.5). Fe(CN)5N03~undergoes first-order decay with the loss of CN™, presumably from the trans position, to form Fe(CN)4N02~(Xmax 615 nm, emax 3.8 X 102 M™1 cm™1) according to the following reactions: Fe(CN)5N03™ Fe(CN)4N02™ + CN™, K = 6.8 X 10~5; CN™ + H+ <=± HCN, K = 2.0 X 109. The observed first-order rate constant for the disappearance of Fe(CN)5N03™ (2.8 X 102 s™1) is independent of the nature of the reducing radical and pH (4.6-8.5); kobsd increases with increasing [H+] (> 10"4 M) or [CN™]. The relative concentrations of the two reduced species depend markedly on pH and [CN™], but not radiation dose. The reduced species are sensitive to 02 generating Fe(CN)5N02", Fe(CN)4NO(OH)2™, and polymeric species. In solutions c Fe(CN)5N03™ reacts rapidly with -CH2C(CH3)2OH (k = 2.Í cm™1), air-insensitive, moderately stable alkylnitroso complex, has been obtained in a KBr matrix.

The thermodynamically favored reaction between water and magnesium, Mg + 2H2O → Mg(OH)2 + H2, is normally sluggish, but it becomes reasonably rapid when a milled composite of powdered magnesium metal and powdered iron (1−10 mol %) is used with sodium chloride solutions. Iron functions as an activator, and chloride functions as a catalyst that depassivates the outermost oxide/hydroxide layer and allows water to penetrate to the activated magnesium surface. Adding solutes such as sodium nitrate, copper(II) chloride, and sodium trichloroacetate to the reaction mixture suppresses the yield of dihydrogen. Manometric and calorimetric studies on the stoichiometry and kinetics of the reaction between Mg(Fe) powders and aqueous solutions demonstrate that short-lived, partially, and fully solvated electrons ( and ) are precursors of dihydrogen and that they and the hydrogen atoms (H•) formed from them can be scavenged, resulting in suppressed dihydrogen yields.