Authors: E. Hayon, T. Ibata, N. N. Lichtin, M. Simic The reactivity and sites of attack of hydroxyl radicals on simple amides in aqueous solution were studied. The following amides were examined: formamide (F), N-methylformamide (NMF), N,N-dimethylformamide (DMF), acetamide (A), N-methylacetamide (NMA), and , -dimethylacetamide (DMA). The rate constants for reaction of OH radical with NMF, DMF, NMA, and DMA…
Authors: Jun-ichi Takahashi, Teruo Hosokawa, Hitomi Masuda, Takeo Kaneko, Kensei Kobayashi, Takeshi Saito, Yuichi Utsumi 1–2 keV x-ray irradiation was carried out using a synchrotron radiation source on simulated primitive earth environment: a gas mixture of carbon monoxide, nitrogen, and water at atmospheric pressure. High-speed liquid chromatography of the hydrolyzed product solution detected amino acids. The amount of amino acids…
Authors: N. Kitadai, S. Maruyama How and where did life on Earth originate? To date, various environments have been proposed as plausible sites for the origin of life. However, discussions have focused on a limited stage of chemical evolution, or emergence of a specific chemical function of proto-biological systems. It remains unclear what geochemical situations could drive all the stages…
Authors: W. Wang, M. N. Schuchmann, Vinzens Bachler, H. Schuchmann, C. Sonntag Hydroxymethyl radical•CH2OH and its radical anion •CH2O- (pKa 10.7) were generated pulse-radiolytically in N2O-saturated aqueous solutions of methanol. The overall decay is by second-order kinetics. At pH ≤ 8 (•CH2OH, 2k = 1.7 × 109 dm3 mol-1 s-1), one observes ethylene glycol and formaldehyde plus methanol in a…
Authors: D. Dondi, D. Merli, L. Pretali, A. Buttafava, A. Faucitano Aqueous solutions of simple organic C1 compounds (methanol and acetonitrile) and ammonia, presumably present on primordial Earth, were subjected to 60Co gamma irradiation (total dose 800 kGy). The irradiation gave a complex mixture of organic compounds leading interestingly to a positive balance of synthesis vs. degradation reactions. In particular,…
Authors: P. S. Rao, M. Simic, E. Hayon The reaction rate constants of e-/sub aq/ and OH radicals with imidazole (ImH), N-methylimidazole (MeIm), histidine, and N-methylhistidine were determined. The k(e-/sub aq/ + S) values were strongly dependent on the state of protonation of the ”pyridine” nitrogen in these molecules, with rates of approximately 5 x 109 M-1 sec-1 at pH…
Authors: Z. D. Draganić, V. Niketić, S. Jovanović, I. G. Draganić Oxygen-free aqueous solutions of NH4CN (0.1 M, pH 9) were exposed to gamma rays from a60Co source, the mixture of nonvolatile products was fractionated, and the fractions were analyzed. The procedures were chosen to make effective investigations of radiolytic products, and to minimize the contributions of chemical changes which…
Authors: I.G. Draganić, Z. D. Draganić, V. M. Marković Fast kinetic spectrophotometry was used to study the absorption spectra of short-living intermediates produced by reactions of RCN molecules with H, e aq- and OH. The spectra were obtained on the microsecond time scale after an electron pulse from a Febetron 707 accelerator in aqueous solutions of the following compounds: hydrocyanic…
Authors: G. A. Infante, P. Jirathana, J. H. Fendler, E. J. Fendler Product yields in the reaction of e;,, .H, -OH and CI,. with thymine and those in the reaction of e^(-)aq and .OH/O-. with thymine- have been determined quantitatively in 60-co-irradiated aqueous thymine solutions in the presence of suitable scavengers. Good material balances between G(- thymine) and G(total products)…
Authors: H. Seki, R. Nagai, M. Imamura The γ radiolysis of a binary mixture of methanol and water over a wide concentration range has been investigated. The observed yields of products are expressed as a linear function of the electron fraction of methanol in the mixture. The yields of molecular hydrogen were also determined. Analyzing the results on reasonable assumptions,…