@article{MTMT:31056770, title = {Unusual Chemistry in an Uncatalyzed Bromate-Aniline Oscillator: Ring-Contraction Oxidation of Aniline with Pulsative CO2 Production}, url = {https://m2.mtmt.hu/api/publication/31056770}, author = {Valent, Ivan and Pribus, Marek and Novak, Filip and Plankova, Sylvia and Blasko, Jaroslav and Kubinec, Robert and Almassy, Ambroz and Filo, Juraj and Sigmundova, Ivica and Sebechlebska, Tana and Lawson Bich, Thuy and Noszticzius, Zoltan}, doi = {10.1021/acs.jpca.9b07766}, journal-iso = {J PHYS CHEM A}, journal = {JOURNAL OF PHYSICAL CHEMISTRY A}, volume = {123}, unique-id = {31056770}, issn = {1089-5639}, abstract = {The bromate-aniline oscillatory reaction was discovered 4 decades ago, but neither the detailed mechanism nor the key products or intermediates of the reaction were described. We report herein a detailed study of this reaction, which yielded new insights. We found that oscillatory oxidation of aniline by acidic bromate proceeds, to a significant extent, via a novel reaction pathway with the periodic release of carbon dioxide. Several products were isolated, and their structures, not described so far, were justified on the basis of MS and NMR. One of the main products of the reaction associated with the CO2 release route can be assigned to 2,2-dibromo-5-(phenylimino)cyclopent-3-en-1-one. A number of known compounds produced in the studied reaction, including unexpected brominated 1-phenylpyrroles and 1-phenylmaleimides, were identified by comparison with standards. A mechanism is suggested to explain the appearance of the detected compounds, based on coupling of the anilino radical with the produced 1,4-benzoquinone. We assume that the radical adduct reacts with bromine to form a cyclopropanone intermediate that undergoes a Favorskii-type rearrangement. Further oxidation and bromination steps including decarboxylation lead to the found brominated phenyliminocyclopentenones. The detected derivatives of 1-phenylpyrrole could be produced by a one-electron oxidation of a proposed intermediate 2-phenylamino-5-bromocyclopenta-1,3-dien-1-ol followed by beta-scission with the abstraction of carbon monoxide. Such a mechanism is known from the combustion chemistry of cyclopentadiene. The proposed mechanism of this reaction provides a framework for understanding the observed oscillatory kinetics.}, year = {2019}, eissn = {1520-5215}, pages = {9669-9681}, orcid-numbers = {Valent, Ivan/0000-0003-3751-7567; Sebechlebska, Tana/0000-0001-5460-8028} } @article{MTMT:2210869, title = {Measurement of Hypoiodous Acid Concentration by a Novel Type Iodide Selective Electrode and a New Method To Prepare HOI. Monitoring HOI Levels in the Briggs-Rauscher Oscillatory Reaction}, url = {https://m2.mtmt.hu/api/publication/2210869}, author = {Muntean, Norbert and Lawson Bich, Thuy and Kály-Kullai, Kristóf and Gyökérné Wittmann, Mária and Noszticzius, Zoltán and Onel, L and Furrow, SD}, doi = {10.1021/jp3015673}, journal-iso = {J PHYS CHEM A}, journal = {JOURNAL OF PHYSICAL CHEMISTRY A}, volume = {116}, unique-id = {2210869}, issn = {1089-5639}, abstract = {A new type of iodide selective electrode prepared by dipping a silver wire into molten silver iodide is reported. The electrode was calibrated for silver and iodide ions and the measured electromotive force for various Ag+ and I- concentrations was close to the theoretical within a few millivolts. Besides Ag+ and I- ions, however, the electrode also responds to hypoiodous acid. Thus, the electrode was calibrated for HOT as well, and for that purpose a new method of hypoiodous acid preparation was developed. To explain the close to Nemstian electrode response for HOI and also the effect of hydrogen ion and iodine concentration on that response, the corrosion potential theory suggested earlier by Noszticzius et al. was modified and developed further. Following oscillations in the Briggs-Rauscher reaction with the new electrode the potential crosses the "solubility limit potential" (SLP) of silver iodide. Potentials below SLP are controlled by the concentration of I-, but potentials above SLP are corrosion potentials determined by the concentration of HOI. Finally, the measured HOI oscillations are compared with calculated ones simulated by a model by Furrow et al.}, keywords = {MODEL; MECHANISM; SYSTEMS; KINETICS; HYDROLYSIS; HYDROGEN-PEROXIDE; Acetone; CO2 EVOLUTION; POTENTIAL RESPONSE; DIIODOMALONIC ACID}, year = {2012}, eissn = {1520-5215}, pages = {6630-6642} } @article{MTMT:1401797, title = {Micropatterned Polyvinyl Butyral Membrane for Acid-Base Diodes}, url = {https://m2.mtmt.hu/api/publication/1401797}, author = {Roszol, László and Lawson Bich, Thuy and Koncz, Viktória Anna and Noszticzius, Zoltán and Gyökérné Wittmann, Mária and Sarkadi, Tamás and Koppa, Pál}, doi = {10.1021/jp106773y}, journal-iso = {J PHYS CHEM B}, journal = {JOURNAL OF PHYSICAL CHEMISTRY B}, volume = {114}, unique-id = {1401797}, issn = {1520-6106}, abstract = {Until now, polyvinyl alcohol (PVA) gel cylinders have been used in electrolyte diodes as a connecting element between the acidic and alkaline reservoirs. In this paper, a new connecting element is reported: a breath figure templated polyvinyl butyral (PVB) membrane prepared with dip-coating from a dichloromethane solution of the polymer in a humid atmosphere. The procedure gives a 1.5-2 mu m thick membrane with a hexagonal pattern, the average characteristic length of which is 1 mu m. After an acidic etching, it was found to be a good connecting element. The voltage-current characteristics and dynamic properties of PVA and PVB were measured and compared. The PVB membrane has a faster response to voltage changes than the PVA gel, but in both cases, there was a slow drift in the current that prevented it from reaching a steady state. Reproducible characteristics can be obtained, however, after the current reaches a well-defined quasi-steady state.}, keywords = {ACIDS; Gels; DICHLOROMETHANE; steady state; PVA-gel; Dynamic property; Current voltage characteristics; Electrolyte diode; Voltage-current characteristics; Voltage change; Thick membranes; Templated; Quasi-steady state; Polyvinyl butyral; Polyvinyl alcohol gels; Micropatterned; Humid atmospheres; Hexagonal pattern; Dip coating; Dichloromethane solutions; Characteristic length; Breath figures; Acid base}, year = {2010}, eissn = {1520-5207}, pages = {13718-13725} } @article{MTMT:1315114, title = {Iodomalonic Acid as an Anti-Inhibitor in the Resorcinol Inhibited Briggs-Rauscher Reaction}, url = {https://m2.mtmt.hu/api/publication/1315114}, author = {Lawson Bich, Thuy and Fulop, J and Gyökérné Wittmann, Mária and Noszticzius, Zoltán and Muntean, Norbert and Szabó, Gabriella Stefánia and Onel, L}, doi = {10.1021/jp907364a}, journal-iso = {J PHYS CHEM A}, journal = {JOURNAL OF PHYSICAL CHEMISTRY A}, volume = {113}, unique-id = {1315114}, issn = {1089-5639}, abstract = {It was found that the inhibitory effect of resorcinol is less pronounced if it is added in a later stage of the Briggs-Rauscher reaction, which indicates that all accumulating intermediate-most probably iodomalonic acid-can suppress the inhibition. In fact, when iodomalonic acid was added to the reaction mixture, the inhibitory period was shortened considerably even at micromolar levels of the iodomalonic acid concentration. Moreover, iodomalonic acid call accelerate the rate of the reaction when applied in the same low concentrations, suggesting that it can be an autocatalytic intermediate of the Briggs-Rauscher reaction.}, keywords = {MODEL; MECHANISM; antioxidants; MALONIC-ACID; OSCILLATING SYSTEM; CO2 EVOLUTION}, year = {2009}, eissn = {1520-5215}, pages = {14095-14098}, orcid-numbers = {Szabó, Gabriella Stefánia/0000-0002-7083-9106} } @article{MTMT:1315115, title = {Reaction Routes Leading to CO2 and CO in the Briggs-Rauscher Oscillator: Analogies between the Oscillatory BR and BZ Reactions}, url = {https://m2.mtmt.hu/api/publication/1315115}, author = {Muntean, Norbert and Szabó, Gabriella Stefánia and Gyökérné Wittmann, Mária and Lawson Bich, Thuy and Fulop, J and Noszticzius, Zoltán and Onel, L}, doi = {10.1021/jp905239w}, journal-iso = {J PHYS CHEM A}, journal = {JOURNAL OF PHYSICAL CHEMISTRY A}, volume = {113}, unique-id = {1315115}, issn = {1089-5639}, abstract = {With Fenton-type experiments, it is shown that the intense CO2/CO evolution in the Briggs-Rauscher (BR) reaction is due to decarboxylation/decarbonylation of organic free radicals. The metal ion applied in the Fenton-type experiments was Fe2+ or Ti3+ or Mn2+ combined with H2O2 or S2O82- as a peroxide, whereas the organic substrate was malonic acid (MA) or a H mixture of MA and iodomalonic acid (IMA). Experiments with a complete BR system applying MA or the MA/IMA mixture indicate that practically all CO2 and CO comes from IMA. The decarboxylation/decarbonylation mechanisms of various iodomalonyl radicals can be analogous to that of the bromomalonyl radicals studied already in the Belousov-Zhabotinsky (BZ) reaction, It is found that an intense CO2/CO evolution requires the simultaneous presence of H2O2, IO3-, Mn2+, and IMA. It is suggested that the critical first step of this complex reaction takes place in the coordination sphere of Mn2+. That first step can initiate a chain reaction where organic and hydroperoxyl radicals are the chain carriers. A chain reaction was already found in a BZ oscillator as well. Therefore, the analogies between the BR and BZ oscillators are due to the fact that in both mechanisms, free radicals and, in most cases, also transition-metal complexes play an important role.}, keywords = {MODEL; SYSTEM; MECHANISM; INHIBITION; SUBSTRATE; EVOLUTION; antioxidants; MALONIC-ACID; BELOUSOV-ZHABOTINSKY REACTION; CARBON-MONOXIDE}, year = {2009}, eissn = {1520-5215}, pages = {9102-9108}, orcid-numbers = {Szabó, Gabriella Stefánia/0000-0002-7083-9106} } @article{MTMT:1122, title = {Alternative reaction channels and carbene intermediates in the Ce4+ - malonic acid and Ce4+ - bromomalonic acid reactions. 1. CO2 measurements}, url = {https://m2.mtmt.hu/api/publication/1122}, author = {Nagygyőry, S and Gyökérné Wittmann, Mária and Pintér, S and Visegrády, A and Dancsó, András and Lawson Bich, Thuy and Noszticzius, Zoltán and Hegedus, L and Forsterling, HD}, doi = {10.1021/jp990330+}, journal-iso = {J PHYS CHEM A}, journal = {JOURNAL OF PHYSICAL CHEMISTRY A}, volume = {103}, unique-id = {1122}, issn = {1089-5639}, abstract = {The Ce4+-malonic/bromomalonic acid reactions play an important role in the oscillatory Belousov-Zhabotinsky reaction. In this work CO2 evolution from these reactions was studied with a sensitive acid quantitative method, by converting the CO2 to methane and measuring it with a flame ionization detector. It was found that the stoichiometries depend on the initial conditions in batch experiments or on the mixing rate of reagents in a semibatch reactor. These findings are explained by two main reaction channels: one for recombination and another for decarboxylation. Decarboxylation itself has two separate routes, one is dominant at low while the other at high Ce4+ concentrations. In the latter, formation of more than two CO2 molecules from one malonic/bromomalonic acid molecule was observed. Novel reaction schemes containing carbenes are proposed for these "high Ce4+" decarboxylation channels. To check the new mechanism, HPLC measurements are planned as a continuation of the research.}, keywords = {HPLC; PRODUCTS; OXIDATION; ORGANIC SUBSET; OSCILLATORY BZ REACTION; BELOUSOV-ZHABOTINSKY-REACTION; CHEMICAL OSCILLATOR}, year = {1999}, eissn = {1520-5215}, pages = {4885-4892}, orcid-numbers = {Dancsó, András/0000-0001-8460-217X} } @article{MTMT:1131, title = {Application of the parametric representation method to construct bifurcation diagrams for highly non-linear chemical dynamical systems}, url = {https://m2.mtmt.hu/api/publication/1131}, author = {Simon L., Péter and Lawson Bich, Thuy and Farkas, Henrik and Noszticzius, Zoltán}, doi = {10.1039/ft9969202865}, journal-iso = {J CHEM SOC FARADAY T}, journal = {JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS}, volume = {92}, unique-id = {1131}, issn = {0956-5000}, abstract = {The parametric representation method has been shown to be a useful geometric tool to study tangent and Hopf bifurcations in chemical systems. As an example, we investigate the behaviour of a two-dimensional system of differential equations. This general model includes some known catalytic oxidation models as special cases. The general system can have one or three stationary solutions depending on the parameter values. The parametric representation method is applied to construct bifurcation diagrams for multistationarity and stability.}, keywords = {FEATURES; OXIDATION; INSTABILITIES; Multiplicity; LANGMUIR-TYPE KINETICS; HETEROGENEOUSLY CATALYZED REACTIONS}, year = {1996}, pages = {2865-2871}, orcid-numbers = {Simon L., Péter/0000-0002-2183-1853} }