Oxidative protein surface mapping has gained popularity over recent years within the mass spectrometry (MS) community for gleaning information about the solvent accessibility of folded protein structures. The hydroxyl radical targets a wide breadth of reactive amino acids with a stable mass tag that withstands subsequent MS analysis. A variety of techniques exist for generating hydroxyl radicals, with most requiring sources of radiation or caustic oxidizing reagents. The purpose of this research was to evaluate the novel use of electrochemistry for accomplishing a comparable probe of protein structure with a more accessible tool. Two different working electrode types were tested across a range of experimental parameters, including voltage, flow rate, and solution electrolyte composition, to affect the extent of oxidation on intact proteins. Results indicated that the boron-doped diamond electrode was most valuable for protein research due to its capacity to produce hydroxyl radicals and its relatively low adsorption profile. Oxidized proteins were collected from the electrochemical cell for intact protein and peptide level MS analysis. Peptide mass spectral data were searched by two different “hybrid” software packages that incorporate de novo elements into a database search to accommodate the challenge of searching for more than forty possible oxidative mass shifts. Preliminary data showed reasonable agreement between amino acid solvent accessibility and the resulting oxidation status of these residues in aqueous solution, while more buried residues were found to be oxidized in “non-native” solution. Later experiments utilized higher flow rates to reduce protein residence time inside the electrochemical flow chamber, along with a different cell activation approach to improve controllability of the intact protein oxidation yield. A multidimensional chromatographic strategy was employed to improve dynamic range for detecting oxidation of lower reactivity residues. Along with increased levels of oxidation around “reactive hotspot” sites, the enhanced sensitivity of these measurements uncovered a significant level of background oxidation in control proteins. While further work is needed to determine the full utility that BDD electrochemistry can lend protein structural studies, the experimental refinements reported here pave the way for improvements that could lead to a high-throughput structural pipeline complementary to predictive modeling efforts.

Low-temperature fuel cells (LTFC) such as phosphoric acid fuel cells (PAFC) and proton exchange membrane fuel cells (PEMFC) are a promising electrochemical energy system for the conversion of hydrogen to electricity. Many challenges must be overcome before commercialization is possible. This dissertation focuses on the degradation of carbon catalyst supports and PEMFC water management. Kinetic studies are presented on the structure-reactivity relationship including an in-depth study of commercially available and model carbons. A mechanism and numerical model of the electrochemical oxidation of graphene-based carbon is proposed to explain longstanding questions. Three mechanisms are concluded to contribute to the current decay commonly observed during electrochemical oxidation: mass loss, reversible passive oxide formation, and irreversible oxide formation. Water uptake and electro-osmosis are investigated to improve the understanding and aid modeling of water transport in PEMFCs below 0 °C. The implication of an electro-osmotic drag coefficient less than unity is discussed in terms of proton transport mechanisms. Capillary pressure saturation relations are presented for carbon fiber paper which can both be used as gas-diffusion layers in PEMFCs. Boundary and scanning curves for imbibition and drainage are measured to further understanding of the hysteresis observed during PEMFC operation.

Solid oxide fuel cells (SOFCs) are promising power generation devices due to its high efficiency and low pollutant emissions. SOFCs operate with a wide range of fuels from hydrogen (H2) to hydrocarbons, and are mainly intended for stationary power generation. Compared to combustion systems, SOFCs have significantly lower environmental impacts. However, the full scale commercialization of SOFCs is impeded by high cost and problems associated with long-term performance and durability. The cell performance can be affected by various internal losses, involving cathode, anode and electrolyte. Anodic losses make a significant contribution to the overall losses, practically in anode-supported cells. Therefore, it is desirable to reduce the anodic losses in order to enhance the overall cell performance. Knowledge of the actual elementary reaction steps and kinetics of electrochemical reactions taking place on the anode is critical for further improvement of the anode performance. Since H2 and carbon monoxide (CO) are the primary reforming products when hydrocarbons are used as SOFC fuels, investigation of electrochemical reactions involving H2 and CO should provide a better understanding of SOFC electrochemical behavior with hydrocarbon feeds. However, still exist uncertainties concerning both H2 and CO electrochemical reactions. The overall objective of this research is to investigate the mechanistic details of H2 and CO electrochemical reactions on SOFC anodes. To achieve this objective, Ni/YSZ pattern anodes were used in the experimental study and as model anodes for the simulation work due to their simplified 2-D structure. The Ni/YSZ pattern anodes were fabricated using a bi-layer resist lift-off method. Imaging resist nLOF2035 and sacrificial resist PGMI SF11 were found to be effective in the bi-layer photolithographic process. Suitable undercut size was found critical for successful pattern fabrication. A simple method, involving taking microscopic photographs of photoresist pattern was developed, to check if the undercut size is large enough for the lift-off; semi-circle wrinkles observable in photographs indicate whether the undercut is big enough for successful pattern anode fabrication. The final product prepared by this method showed straight and clear Ni patterns. A systematic study was performed to determine the stable conditions for Ni/YSZ pattern anode performance. The microstructure and electrochemical behavior changes of the pattern anode were evaluated as a function of Ni thickness, temperature and H2O content in H2 environment. Ni/YSZ pattern anodes with 0.5 µm thick Ni were tested in dry H2 at 550°C without significantly changing the TPB line. Ni/YSZ pattern anodes with Ni thickness of 0.8 µm were tested at 550°C under dry and humidified H2 (3-70% H2O) conditions without TPB line change. For 0.8 µm thick patterns, the TPB length showed pronounced changes in the presence of H2 with 3-70% H2O at 700°C. Significant increase in TPB length due to hole formation was observed at 800°C with 3% and 10% H2O. Ni/YSZ pattern anodes with 1.0 µm thick Ni were stable in H2 with 3% H2O in the range 500-800°C, with only slight changes in the TPB line. Changes of TPB line and Ni microstructure were observed in the presence of 3-70% H2O above 700C. Stabilization of the pattern anode performance depends on temperature. To accelerate stabilization of the cell, pre-treatment of the cell in H2 with 3% H2O for ~22 hrs at 750°C or 800°C could be performed. In addition, comprehensive data sets for H2 and CO electrochemical oxidation reactions on Ni/YSZ pattern anodes were obtained under stable test conditions. For the H2/H2O system, the polarization resistance (Rp) increases as temperature, overpotential, H2 partial pressure, TPB length decreases. Rp is also dependent on H2O content. When the H2O content is between 3% and 30-40%, Rp decreased with increasing H2O content. However, Rp is less affected with further increases in H2O content. For the CO/CO2 system, polarization resistance depends on partial pressure of CO and CO2, temperature and overpotential. Moreover, the polarization resistance decreases when the partial pressure of CO2 and temperature increase. The partial pressure of CO has a positive effect on the polarization resistance. The polarization resistance decreases to a minimum when the overpotential is 0.1 V. For both H2 and CO electrochemical oxidations, charge transfer reactions contribute to the rate limiting steps. A 1-D dynamic SOFC half-cell model considering multiple elementary reaction kinetics was developed. The model describes elementary chemical reactions, electrochemical reactions and surface diffusion on Ni/YSZ pattern anodes. A new charge transfer reactions mechanism proposed by Shishkin and Ziegler (2010) based on Density Functional Theory (DFT) was investigated through kinetic modeling and pattern anode experimental validation. This new mechanism considers hydrogen oxidation at the interface of Ni and YSZ. It involves a hydrogen atom reacting with the oxygen ions bound to both Ni and YSZ to produce hydroxyl (charge transfer reaction 1), which then reacts with the other hydrogen atom to form water (charge transfer reaction 2). The predictive capability of this reaction mechanism to represent our experimental results was evaluated. The simulated Tafel plots were compared with our experimental data for a wide range of H2 and H2O partial pressures and at different temperatures. Good agreements between simulations and experimental results were obtained. Charge transfer reaction 1 was found to be rate-determining under cathodic polarization. Under anodic polarization, a change in rate-limiting process from charge transfer reaction 1 to charge transfer reaction 2 was found when increasing the H2O partial pressure. Surface diffusion was not found to affect the H2 electrochemical performance.

As a novel high temperature fuel cell, the direct carbon fuel cell (DCFC) is drawing ever-increasing attention due to its significant high conversion efficiency, diversified fuel resources and low pollution compared with conventional coal-fired power plants. Despite the advantages of the DCFC technology, there are a number of fundamental and technological challenges which need to be overcome for its further development and commercialization. One of the major hurdles in current study of the DCFC is that the efficacy of carbon fuels is still unclear. Meanwhile, the effects of impurities in the carbon fuels on the performance and lifetime of the DCFC are still up for debate. Furthermore, the molecular-level study on the mechanism of electrochemical oxidation of carbon fuels in the DCFC is limited by the lack of techniques to detect the reaction intermediates at high temperature. Finally, how to scale up the DCFC system with suitable hardware materials and optimum structural designs needs further investigation. Based on successfully developing a DCFC system with a stirring molten carbonate electrolyte, various commercial and self-made carbon fuels including activated carbons, carbon blacks, graphitic carbons, coals and carbon nanofibers (CNFs) are systematically characterized and evaluated in this thesis. It is found that the nature of carbon fuels plays an important role in the anodic performance of the DCFC. A higher surface area and a smaller particle size of carbon fuel can effectively improve its electrochemical reactivity by increasing the interaction between the carbon particles and the molten carbonate electrolyte. On the contrary, a higher graphitic degree of carbon fuel results in a lower electrochemical reactivity in the DCFC due to the less reactive sites such as edges and defects on carbon surface. Furthermore, the order of the electrochemical reactivities for carbon fuels is in good agreement with the concentration of oxygen-containing functional groups on their surface, which is believed to play a key role in the electrochemical oxidation of carbons in the DCFC. In order to better understand the relationship between the surface chemistry of carbons and their electrochemical performance in the DCFC, various pre-treatment techniques including acid washing, air-plasma treatment, air oxidation, pyrolysis and the pre-electrochemical oxidation (in molten alkali carbonate electrolytes) have been conducted on the carbon fuels. It is shown that both the HNO3 washing and pre-electrochemical oxidation are much more effective to improve the electrochemical reactivities of carbon fuels compared to other pre-treatment techniques, which is attributed to the significant changes in the microstructure of carbon fuels and more surface oxygen functional groups produced during the pre-treatments. In contrast, the pyrolysis treatment results in a sharp decrease of electrochemical reactivity of carbon fuels due to the decreases in oxygen-containing surface groups and surface areas, and the increase of their graphitic degrees. For the sake of the optimum operational conditions for the DCFC system, the influences of stirring rates, the carbon fuel loadings and fuel cell temperatures on the anodic performance of the DCFC are investigated. It has been shown that the carbon discharge rates can be significantly boosted by effective stirring and high carbon fuel concentrations due to an improved mass transport. A higher operation temperature can also increase the current density and open circuit voltage of the DCFC. However, the complete electrochemical oxidation of carbon into CO2 can be only achieved at the low operation temperature of 600-700 ºC, while the partially electrochemical oxidation of carbon into CO occurs at 800 ºC, which will significantly decrease the carbon efficiency to less than 10% at 800 ºC. In the study of self-made CNFs as fuels for the DCFC, both microstructure and electrochemical reactivity of CNFs are highly dependent on their synthesis conditions. Compared with Ni-Al2O3 catalyst, the coprecipitated Ni-Cu-Al2O3 catalyst produced more CNFs with higher electrochemically reactivity. Over the same catalyst, the CNFs synthesized at lower temperature typically have higher surface areas, more surface oxygen functional groups and lower graphitic degrees, thereby leading to a higher electrochemical reactivity in the DCFC tests. In an effort to study the catalytic effects of mineral impurities on the electrochemical performance of the DCFC, Al2O3 and SiO2 present passivation effects in the anodic reaction. In contrast, the CaO, MgO and Fe2O3 show catalytic effects in the carbon electrochemical oxidation, which is demonstrated by the increases of current densities at low over-potentials in the polarization curves.

The treatment of advanced nuclear fuels is relevant to the stabilisation of legacy spent fuels or nuclear materials and fuels from future nuclear reactors. Historically, spent fuel reprocessing has been driven to recover uranium and plutonium for reuse. Future fuel cycles may also recover the minor actinides neptunium, americium and perhaps curium. These actinides would be fabricated into new reactor fuel to produce energy and for transmutation of the minor actinides. This has the potential to reduce the long lived radioactivity of the spent fuel and reprocessing high level waste, whilst also maximising energy production. To achieve these aims there are a range of materials that could be used as advanced nuclear fuels, these include metals, oxides, carbides, nitrides and composite materials, and these fuels may also be alloyed. These advanced fuels may need to be reprocessed, and as head end is the first chemical treatment step in a reprocessing plant, the issues caused by treating these advanced fuels are faced primarily by head end. Changes to the overall reprocessing specification, such as reduction in discharge authorisations for volatile radionuclides, will have the greatest impact upon head end. All these factors may lead to the introduction of pre-treatment technologies (e.g. Voloxidation) or enhanced dissolution technologies, e.g. mediated dissolution using silver(II).Literature and experimental studies show that uranium dioxide and low plutonium content MOx dissolves in nitric acid via direct and indirect nitrate reduction. The indirect nitrous acid catalysed route is kinetically most significant. The kinetics for the dissolution of uranium dioxide and 5 % plutonium MOx have been derived experimentally. Studies of the dissolution of MOx pellets in concentrated nitric acid and near boiling conditions indicate that dissolution shows a degree of mass transfer limitation. Thermodynamic studies show that the pronounced reduction in the MOx dissolution extent at 30-40% plutonium is due to the thermodynamics of the key dissolution reactions. One technology that could be used to dissolve plutonium-rich residues that are generated from the reprocessing of MOx fuels is mediated dissolution. Inactive studies using linear staircase voltammetry (LSCV) and constant current bulk electrolysis (BE) have been used to optimise a 100 ml dissolution cell. The generation of silver(II) is dependent upon silver concentration, agitation and the size of the separator membrane. Whilst the stability of silver(II) is defined by the kinetics of water oxidation, this is dependent upon a number of factors including nitric acid concentration, silver(I):(II) ratio, temperature and the rate of migration from the catholyte into the anolyte. LSCV experiments have shown that Tafel analysis confirms there is a good relationship between potential and anode current density assuming oxygen evolution and silver(I) oxidation. Kinetic modelling of the BE experiments can be used to model the silver(II) generation, steady state and decomposition due to reaction with water. The dissolution cell has been demonstrated to be capable of dissolving plutonium dioxide to 200 g.l-1 in less than 2 hours with good faradaic efficiency.

The aim of this study is forced oxidative degradation of active pharmaceutical ingredient abacavir, used to treat HIV-infected patients. A fast and sensitive method for the determination of abacavir and its degradation products by ultra-high performance liquid chromatography has been developed and validated, that made it possible to evaluate the oxidation stability of abacavir and Ziagen tablets. Suitable chromatographic separation was achieved using a Kinetex C18 column and gradient elution with a mobile phase consisting of acetonitrile and ammonium acetate (c = 20 mmol dm−3 , pH = 7.0). The total run time was 11 minutes. The determination of abacavir and its degradation products was performed by a photodiode array detector at λ = 254 nm. The optimized method for the determination of abacavir and its degradation products was applied to study the oxidation of abacavir by both traditional and electrochemical approaches. The forced degradation study in solution revealed abacavir instability in the presence of 3% hydrogen peroxide and during electrochemical oxidation. The study found that excipients in the tablet suppress the degradation of abacavir by approximately 10 %. Abacavir is oxidized by 15 % by hydrogen peroxide after 24 hours at 25 řC, after 1.5 hours at 50 řC and after 5 minutes at...

No description available.

The study of the substituent effect on the voltammetric behaviour of newly synthesized N benzyl-salicylthioamides and the preparation and identification of products of their electrooxidation were the aims of this thesis. The voltametric characteristics were measured by DC voltammetry on a rotating disc electrode in a non-aqueous media. Using QSER, the effect of substituents on the anodic half wave potential was quantified, and statistically valid correlation equations were obtained. The influence of reaction media on the compounds electrooxidation was also studied. Using preparative electrolysis, the electrooxidation products of two selected N benzylsalicylthioamides were obtained. The one (structurally similar) product was identified in both cases. The following general scheme of electrochemical oxidation of N-benzylsalicylthioamides studied was proposed: the electrooxidation starts on sulphur atom by elimination of electrons, followed by translocation of charge on nitrogen atom, then hydrogen sulphite is eliminated, and a new ring is closed between two molecules of appropriate N-benzylsalicylthioamide.

Neste trabalho foi estudada a oxidação eletroquímica da seguinte série de substratos: (Ver no arquivo PDF). Para tanto foram empregadas a voltametria cíclica e eletrólises preparativas (diretas e indiretas), a potencial ou corrente controlados, em celas de um ou dois compartimentos. Os estudos voltamétricos foram realizados em MeCN/0,1M NaClO4 ou MeOH/0,2M NaClO4/0,2M NaOMe com anodo de platina, utilizando Ag/AgI (0,04M TBAI) ou Ag/Ag+ (0,01M AgNO3) respectivamente como sistemas de referência. Os experimentos eletrolíticos foram conduzidos em MeCN/0,1M NaClO4 ou MeOH/0,2M NaClO4/0,2M NaOMe utilizando anodo de platina, catodo de platina ou tungstênio e os mesmos sistemas de referência citados acima. Nas eletrólises a potencial controlado, efetuadas em acetonitrila, foram obtidos os 4,4\' ,5,5\' -tetrametóxi-bifenilos-2,2\' -substituídos correspondentes dos substratos 3 e 5-12, na faixa de 50-74% de rendimento e do substrato (13) em 12%. Este processo é sensível à concentração de base, sendo dificultado à medida que a concentração de 2,6-lutidina aumenta. Na eletrólise indireta, realizada em MeCN contendo piridina, com o substrato 2, mediada por Fe(bpy)3(PF6)2 foi obtida acetona (1) em 70%; nas realizadas com o substrato 3, mediadas por Fe(bpy)3(PF6)2, [Fe(dafipy)2](PF6)2 ou (4-Br-C6H4)3N, foi obtido o dímero correspondente na faixa de 26-53%, em ausência de base. Na presença de base e do mediador Fe(bpy)3(PF6)2, a eletrólise de 3 em acetonitrila levou à mistura de cetona 1 - 6,6% e álcool 2 - 28,2%. Nas eletrólises a corrente controlada, em MeOH/NaOMe, realizadas com os substratos 1, 3, 4 e 14 foram obtidos produtos resultantes da metoxilação do anel aromático como por exemplo o 1 -acetil-4,5,5,6-tetrametóxi-cicloexa-1,3-dieno, isolado em 71 % na eletrólise do substrato 1. Com base nos tipos de produtos obtidos, em exemplos da literatura e em cálculos semi-empíricos, foram formuladas propostas mecanísticas para explicação dos resultados eletrolíticos. / In the present work the electrochemical oxidation of the following 4-substituted-1,2-dimethoxybenzenes was investigated: (See file PDF). The compounds listed above were studied using cyclic voltammetry and preparative electrolyses, carried out under potential or current control, in divided or undivided cells. The voltammetric experiments were performed in MeCN/0.1M NaClO4 or MeOH/0.2M NaClO4/0.2M NaOMe using platinum anode; as reference systems Ag/AgI (0,04M TBAI) or Ag/Ag+ (0,01M AgNO3) were employed. The electrolytic experiments were carried out in MeCN/0.1M NaClO4 or MeOH/0.2M NaClO4/0.2M NaOMe using platinum anode and platinum or tungsten cathodes and the same reference systems mentioned above. Current controlled electro1yses of substrates 3, 5-13 in MeCN afforded 2,2\' disubstituted-4,4\'-5,5\' - tetramethoxy-biphenyls in 50-74% yields except 13 (12%). This process showed to be base sensitive, and, increasing 2,6-lutidine concentration dimerization was progressively suppressed. Indirect electrolysis of substrate 2 in MeCN containing pyridine, mediated by Fe(bpy)3(PF6)2, afforded ketone (1) in 70% yield. Under similar conditions but absence of base, in the presence of Fe(bpy)3(PF6)2, [Fe(dafipy)2](PF6)2 or (4-Br-C6H4)3N the corresponding dimeric product was isolated in 26-53% yields. Using Fe(bpy)3(PF6)2 as mediator and 2,6-lutidine as base, the electrolysis of 3 in acetonitrile led to a ketone 1/ alcohol 2 mixture (6.6 and 28.2%). Current controlled electrolyses carried out in MeOH/NaOMe, with substrates 1, 3, 4 and 14 afforded only nuclear methoxylation products, e.g. l-acetyl-4,5,5,6-tetramethoxy-cyclohexa-1,3-diene, isolated in 71 % yield from the electrolysis of substrate 1. Mechanistic proposals for the electrochemical oxidation of the examined substrates were made based on electrochemical methods, product analysis and semi-empirical molecular orbital ca1culations.

Neste trabalho foi estudada a oxidação eletroquímica da seguinte série de substratos: (Ver no arquivo PDF). Para tanto foram empregadas a voltametria cíclica e eletrólises preparativas (diretas e indiretas), a potencial ou corrente controlados, em celas de um ou dois compartimentos. Os estudos voltamétricos foram realizados em MeCN/0,1M NaClO4 ou MeOH/0,2M NaClO4/0,2M NaOMe com anodo de platina, utilizando Ag/AgI (0,04M TBAI) ou Ag/Ag+ (0,01M AgNO3) respectivamente como sistemas de referência. Os experimentos eletrolíticos foram conduzidos em MeCN/0,1M NaClO4 ou MeOH/0,2M NaClO4/0,2M NaOMe utilizando anodo de platina, catodo de platina ou tungstênio e os mesmos sistemas de referência citados acima. Nas eletrólises a potencial controlado, efetuadas em acetonitrila, foram obtidos os 4,4\' ,5,5\' -tetrametóxi-bifenilos-2,2\' -substituídos correspondentes dos substratos 3 e 5-12, na faixa de 50-74% de rendimento e do substrato (13) em 12%. Este processo é sensível à concentração de base, sendo dificultado à medida que a concentração de 2,6-lutidina aumenta. Na eletrólise indireta, realizada em MeCN contendo piridina, com o substrato 2, mediada por Fe(bpy)3(PF6)2 foi obtida acetona (1) em 70%; nas realizadas com o substrato 3, mediadas por Fe(bpy)3(PF6)2, [Fe(dafipy)2](PF6)2 ou (4-Br-C6H4)3N, foi obtido o dímero correspondente na faixa de 26-53%, em ausência de base. Na presença de base e do mediador Fe(bpy)3(PF6)2, a eletrólise de 3 em acetonitrila levou à mistura de cetona 1 - 6,6% e álcool 2 - 28,2%. Nas eletrólises a corrente controlada, em MeOH/NaOMe, realizadas com os substratos 1, 3, 4 e 14 foram obtidos produtos resultantes da metoxilação do anel aromático como por exemplo o 1 -acetil-4,5,5,6-tetrametóxi-cicloexa-1,3-dieno, isolado em 71 % na eletrólise do substrato 1. Com base nos tipos de produtos obtidos, em exemplos da literatura e em cálculos semi-empíricos, foram formuladas propostas mecanísticas para explicação dos resultados eletrolíticos. / In the present work the electrochemical oxidation of the following 4-substituted-1,2-dimethoxybenzenes was investigated: (See file PDF). The compounds listed above were studied using cyclic voltammetry and preparative electrolyses, carried out under potential or current control, in divided or undivided cells. The voltammetric experiments were performed in MeCN/0.1M NaClO4 or MeOH/0.2M NaClO4/0.2M NaOMe using platinum anode; as reference systems Ag/AgI (0,04M TBAI) or Ag/Ag+ (0,01M AgNO3) were employed. The electrolytic experiments were carried out in MeCN/0.1M NaClO4 or MeOH/0.2M NaClO4/0.2M NaOMe using platinum anode and platinum or tungsten cathodes and the same reference systems mentioned above. Current controlled electro1yses of substrates 3, 5-13 in MeCN afforded 2,2\' disubstituted-4,4\'-5,5\' - tetramethoxy-biphenyls in 50-74% yields except 13 (12%). This process showed to be base sensitive, and, increasing 2,6-lutidine concentration dimerization was progressively suppressed. Indirect electrolysis of substrate 2 in MeCN containing pyridine, mediated by Fe(bpy)3(PF6)2, afforded ketone (1) in 70% yield. Under similar conditions but absence of base, in the presence of Fe(bpy)3(PF6)2, [Fe(dafipy)2](PF6)2 or (4-Br-C6H4)3N the corresponding dimeric product was isolated in 26-53% yields. Using Fe(bpy)3(PF6)2 as mediator and 2,6-lutidine as base, the electrolysis of 3 in acetonitrile led to a ketone 1/ alcohol 2 mixture (6.6 and 28.2%). Current controlled electrolyses carried out in MeOH/NaOMe, with substrates 1, 3, 4 and 14 afforded only nuclear methoxylation products, e.g. l-acetyl-4,5,5,6-tetramethoxy-cyclohexa-1,3-diene, isolated in 71 % yield from the electrolysis of substrate 1. Mechanistic proposals for the electrochemical oxidation of the examined substrates were made based on electrochemical methods, product analysis and semi-empirical molecular orbital ca1culations.