151-51-9Relevant articles and documents
Investigation of the redox interaction between iron(III) 5,10,15,20-tetrakis(p-sulfonatophenyl)porphyrinate and aminoiminomethanesulfinic acid in aqueous solution
Lepentsiotis, Vasilios,Van Eldik, Rudi,Stulov, Dimitri M.,Makarov, Sergei V.
, p. 2915 - 2920 (1998)
Stability studies have been made on aminoiminomethanesulfinic acid [aimsa, thiourea dioxide, (NH2)2CSO2] and the reactions of aimsa and its decomposition product (dithionite, S2O42-) with iron(III) 5,10,15,20-tetrakis-(p-sulfonatophenyl)porphyrinate [FeIII(tpps)] in the presence of oxygen have been investigated. Application of NMR and stopped-flow spectrophotometry revealed direct evidence for the existence of two different forms of aimsa in aqueous solution. The slow formation of one of these forms, NH2NHCSO2H, is shown to determine the strong dependence of the reactivity of aimsa on the age of the stock solutions. Both aimsa and dithionite react in a similar way with FeIII(tpps) in alkaline solutions. The SO2?- radical plays a key role in the redox reactions. The ratio of the oxygen and radical concentration determines which kind of reaction (oxidation, reduction or decomposition) will dominate. In general a high oxygen concentration and a low radical concentration favour the oxidation and decomposition of the metalloporphyrin, whereas a high radical concentration and a low oxygen concentration favour the reduction. In strongly basic solutions ([NaOH] = 0.5 M) a redox cycle between FeIII(tpps) and FeII(tpps) is observed at low aimsa and dithionite concentration. Possible mechanisms for the decomposition of aimsa in alkaline solutions, as well as for the reactions between FeIII(tpps) and aimsa or dithionite, are proposed.
Photochemistry of 1- and 2-Methyl-5-aminotetrazoles: Structural Effects on Reaction Pathways
Ismael,Fausto,Cristiano
, p. 11656 - 11663 (2016/12/09)
The influence of the position of the methyl substituent in 1- and 2-methyl-substituted 5-aminotetrazoles on the photochemistry of these molecules is evaluated. The two compounds were isolated in an argon matrix (15 K) and the matrix was subjected to in situ narrowband UV excitation at different wavelengths, which induce selectively photochemical transformations of different species (reactants and initially formed photoproducts). The progress of the reactions was followed by infrared spectroscopy, supported by quantum chemical calculations. It is shown that the photochemistries of the two isomers, 1-methyl-(1H)-tetrazole-5-amine (1a) and 2-methyl-(2H)-tetrazole-5-amine (1b), although resulting in a common intermediate diazirine 3, which undergoes subsequent photoconversion into 1-amino-3-methylcarbodiimide (H2N-N=C=N-CH3), show marked differences: formation of the amino cyanamide 4 (H2N-N(CH3)-C=N) is only observed from the photocleavage of the isomer 1a, whereas formation of the nitrile imine 2 (H2N-C-=N+=N-CH3) is only obtained from photolysis of 1b. The exclusive formation of nitrile imine from the isomer 1b points to the possibility that only the 2H-tetrazoles forms can give a direct access to nitrile imines, while observation of the amino cyanamide 4 represents a novel reaction pathway in the photochemistry of tetrazoles and seems to be characteristic of 1H-tetrazoles. The structural and vibrational characterization of both reactants and photoproducts has been undertaken.
Meteorites as catalysts for prebiotic chemistry
Saladino, Raffaele,Botta, Giorgia,Delfino, Michela,Di Mauro, Ernesto
, p. 16916 - 16922 (2014/01/06)
From outer space: Twelve meteorite specimens, representative of their major classes, catalyse the synthesis of nucleobases, carboxylic acids, aminoacids and low-molecular-weight compounds from formamide (see figure). Different chemical pathways are identified, the yields are high for a prebiotic process and the products come in rich and composite panels.
