Electron transfer and subsequent reactions during electrochemical oxidation of aryl- and alkylthio derivatives of mucochloric acid

The electrochemical oxidation of aryl- and alkylthio derivatives of mucochloric acid (3,4-dichloro-5-hydroxyfuran-2(5H)-one) in MeCN-Bu 4NBF4 (0.1 mol L-1) was investigated. It was shown that all sulfides are electrochemically active, from one to five oxidation steps of sulfur-containing groups were observed for them. The ease and direction of oxidation of the thio group depend on its nature and position in the furanone ring. 3-Substituted 2(5H)-furanones possess the lowest oxidation potential. 4-Substituted 2(5H)-furanones are predominantly oxidized to sulfoxides, 5-aryl- and -alkylthio derivatives undergo fragmentation to give mucochloric acid, and 3-arylthio derivative gives complex unidentified mixture of products. In the case of 3,4-bis(4-methylphenylthio) derivative, the oxidation product of the arylthio group at the 3 position to the corresponding sulfoxide was isolated. Based on the data from cyclic voltammetry with different concentrations of a substrate and water added, the results of preparative electrolysis and quantum chemical calculations, possible mechanisms of electrochemical oxidation of mucochloric acid-derived sulfides are discussed. The initial common step is a reversible single-electron transfer from the substrate molecule to form highly reactive radical cation. © 2009 Springer Science+Business Media, Inc

ELECTROCATALYTIC PROPERTIES OF PALLADIUM (II) ORGANIC COMPLEXES IN THE NESPHERE ELECTROCHEMICAL OXIDATION OF GLUCOSE

The aim of this work was to study the electrocatalytic properties of palladium (II) com-plexes immobilized on the surface of a working electrode in a neutral medium in relation to the electrochemical oxidation of glucose.Работа выполнена при финансовой поддержке Российского Научного Фонда (проект № 20-13-00142)

Electron transfer and subsequent reactions during electrochemical oxidation of aryl- and alkylthio derivatives of mucochloric acid

The electrochemical oxidation of aryl- and alkylthio derivatives of mucochloric acid (3,4-dichloro-5-hydroxyfuran-2(5H)-one) in MeCN-Bu 4NBF4 (0.1 mol L-1) was investigated. It was shown that all sulfides are electrochemically active, from one to five oxidation steps of sulfur-containing groups were observed for them. The ease and direction of oxidation of the thio group depend on its nature and position in the furanone ring. 3-Substituted 2(5H)-furanones possess the lowest oxidation potential. 4-Substituted 2(5H)-furanones are predominantly oxidized to sulfoxides, 5-aryl- and -alkylthio derivatives undergo fragmentation to give mucochloric acid, and 3-arylthio derivative gives complex unidentified mixture of products. In the case of 3,4-bis(4-methylphenylthio) derivative, the oxidation product of the arylthio group at the 3 position to the corresponding sulfoxide was isolated. Based on the data from cyclic voltammetry with different concentrations of a substrate and water added, the results of preparative electrolysis and quantum chemical calculations, possible mechanisms of electrochemical oxidation of mucochloric acid-derived sulfides are discussed. The initial common step is a reversible single-electron transfer from the substrate molecule to form highly reactive radical cation. © 2009 Springer Science+Business Media, Inc

Electron transfer and subsequent reactions during electrochemical oxidation of aryl- and alkylthio derivatives of mucochloric acid

The electrochemical oxidation of aryl- and alkylthio derivatives of mucochloric acid (3,4-dichloro-5-hydroxyfuran-2(5H)-one) in MeCN-Bu 4NBF4 (0.1 mol L-1) was investigated. It was shown that all sulfides are electrochemically active, from one to five oxidation steps of sulfur-containing groups were observed for them. The ease and direction of oxidation of the thio group depend on its nature and position in the furanone ring. 3-Substituted 2(5H)-furanones possess the lowest oxidation potential. 4-Substituted 2(5H)-furanones are predominantly oxidized to sulfoxides, 5-aryl- and -alkylthio derivatives undergo fragmentation to give mucochloric acid, and 3-arylthio derivative gives complex unidentified mixture of products. In the case of 3,4-bis(4-methylphenylthio) derivative, the oxidation product of the arylthio group at the 3 position to the corresponding sulfoxide was isolated. Based on the data from cyclic voltammetry with different concentrations of a substrate and water added, the results of preparative electrolysis and quantum chemical calculations, possible mechanisms of electrochemical oxidation of mucochloric acid-derived sulfides are discussed. The initial common step is a reversible single-electron transfer from the substrate molecule to form highly reactive radical cation. © 2009 Springer Science+Business Media, Inc

Electron transfer and subsequent reactions during electrochemical oxidation of aryl- and alkylthio derivatives of mucochloric acid

The electrochemical oxidation of aryl- and alkylthio derivatives of mucochloric acid (3,4-dichloro-5-hydroxyfuran-2(5H)-one) in MeCN-Bu 4NBF4 (0.1 mol L-1) was investigated. It was shown that all sulfides are electrochemically active, from one to five oxidation steps of sulfur-containing groups were observed for them. The ease and direction of oxidation of the thio group depend on its nature and position in the furanone ring. 3-Substituted 2(5H)-furanones possess the lowest oxidation potential. 4-Substituted 2(5H)-furanones are predominantly oxidized to sulfoxides, 5-aryl- and -alkylthio derivatives undergo fragmentation to give mucochloric acid, and 3-arylthio derivative gives complex unidentified mixture of products. In the case of 3,4-bis(4-methylphenylthio) derivative, the oxidation product of the arylthio group at the 3 position to the corresponding sulfoxide was isolated. Based on the data from cyclic voltammetry with different concentrations of a substrate and water added, the results of preparative electrolysis and quantum chemical calculations, possible mechanisms of electrochemical oxidation of mucochloric acid-derived sulfides are discussed. The initial common step is a reversible single-electron transfer from the substrate molecule to form highly reactive radical cation. © 2009 Springer Science+Business Media, Inc

2004–2016 Wintertime Atmospheric Blocking Events over Western Siberia and Their Effect on Surface Temperature Anomalies

Western Siberia is a large area in Northern Eurasia, which lies between the Urals and the Yenisei River. The atmospheric blocking events are not a frequent phenomenon in this region. Nevertheless, they noticeably affect the weather and living conditions of people there. We have investigated 14 winter blocking events, identified over Western Siberia, over 2004–2016, and have studied their effect on the surface temperature in this region. We have compared each of the 14 blocking events to the corresponding surface temperature anomalies in the north and in the south of Western Siberia. As a result, the temperature anomalies were separated into two groups: (1) dipole, with a positive surface temperature anomaly (or close to the norm) in the north, and with a negative anomaly (or close to the norm) in the south, and (2) non-dipole. Ten events were attributed to Group 1, four events were referred to Group 2. Analyzing the potential temperature on the dynamic tropopause (advection characteristic) showed that the Group 1 events feature strong advection over the investigated territory. In the non-dipole situations from Group 2 Western Siberia are away from strong blocking events

Wintertime Atmospheric Blocking Events over Western Siberia in the Period 2004–2016 and Their Influence on the Surface Temperature Anomalies

We study wintertime blocking events in 2004–2016 over Western Siberia (WS) and their influence on the surface temperature. The period 2004–2016 is very interesting for study because there has been an increase in the blocking frequency over WS beginning with 2004. We used data ECMWF ERA-Interim and blocking criterion proposed by Tibaldi and Molteni. We investigated blockings events with duration of 5 days or more for winter interval (1 November–31 March). We have chosen 15 blockings events. For each event we calculate surface temperature anomaly in the grid points for two sectors 60–90 E; 50–60 N (southern part of WS) and 60–90 E; 60–70 N (northern part of WS). To estimate advective transfer for studied events we analyzed the potential temperature on the dynamical tropopause. We showed that wintertime blocking events over WS lead to the surface temperature increase in the northern part of West Siberia and to the surface temperature decrease in the southern part of WS. This feature apparently due to warm air masses advection from south-west on the western periphery of the blocking ridge and arctic air masses intrusion to the southern part of the WS on the eastern periphery of this ridge

2004–2016 Wintertime Atmospheric Blocking Events over Western Siberia and Their Effect on Surface Temperature Anomalies

Western Siberia is a large area in Northern Eurasia, which lies between the Urals and the Yenisei River. The atmospheric blocking events are not a frequent phenomenon in this region. Nevertheless, they noticeably affect the weather and living conditions of people there. We have investigated 14 winter blocking events, identified over Western Siberia, over 2004–2016, and have studied their effect on the surface temperature in this region. We have compared each of the 14 blocking events to the corresponding surface temperature anomalies in the north and in the south of Western Siberia. As a result, the temperature anomalies were separated into two groups: (1) dipole, with a positive surface temperature anomaly (or close to the norm) in the north, and with a negative anomaly (or close to the norm) in the south, and (2) non-dipole. Ten events were attributed to Group 1, four events were referred to Group 2. Analyzing the potential temperature on the dynamic tropopause (advection characteristic) showed that the Group 1 events feature strong advection over the investigated territory. In the non-dipole situations from Group 2 Western Siberia are away from strong blocking events