Anodic oxidation, ammonia

PbOj, 40 155-156 oxygen evolution, 40 109-110 reaction, history, 40 97 solid oxide fuel cells, 40 149-150 Anodic oxidation, ammonia, 38 13 1,8-ANS inclusions, 32 453 54 Antagonism, 25 338, 339 Anthracene... 

GP 1] [R 1] A comparison of four micro reactors with different Pt loadings (Pt impregnated on anodically oxidized alumina support) and different Pt structures confirmed that cluster size has an impact on the single Pt-atom activity (6 vol.-% NHj, 88 vol.-% O2, balance He 0.51 ms 260-380 °C) [28, 98]. At low Pt loadings, isolated atoms are formed. Calculated ammonia consumption rates amount to 20 s at 300 °C. At high Pt loadings, clusters are formed. Turn over frequencies (TOP) of about 40 s are determined. 

CI2 evolution reaction, 38 56 electrochemical desorption, 38 53-54 electrode kinetics, 38 55-56 factors that determine, 38 55 ketone reduction, 38 56-57 Langmuir adsorption isotherm, 38 52 recombination desorption, 38 53 surface reaction-order factor, 38 52 Temkin and Frumkin isotherm, 38 53 real-area factor, 38 57-58 regular heterogeneous catalysis, 38 10-16 anodic oxidation of ammonia, 38 13 binding energy quantification, 38 15-16 Haber-Bosch atrunonia synthesis, 38 12-13... 

The indirect anodic oxidation of ketones 42 in ammonia - containing methanol using iodide as a mediator afforded 2,5-dihydro-IH-imidazols 44 via oxidation of the intermediate ketimine 43 to AT-iodo imine followed by elimination of HI to afford the nitrenium ion, which subsequently reacts with ketimine 43 to give the product 44 [73] (Scheme 23). 

Anodic oxidation of 6- and 7-pteridone, using electrolysis at a controlled potential, gave pteridine-6,7-dione in 95-100% yield.409 Under controlled-potential electrolysis conditions pteridine-6,7-dione is oxidized to the bridgehead diol, which undergoes rearrangement, further oxidation, and hydrolysis, yielding tetraketopiperazine, oxamide, urea, oxamic acid, ammonia, formaldehyde, formic acid, and C02-... 

E. C. Szarvasky found that the electrolysis of hydroxylamine was accompanied by the spontaneous transformation of hydroxylamine into ammonia. Secondary reactions always occur—the base being reduced to ammonia at the cathode and at the anode oxidized to nitrogen oxides. F. Balia found that with various electrodes the percentage current yield of NaN02 NaN03 in the electrolytic oxidation of hydroxylamine with anodes of different metals was as follows ... 

It can be clearly seen from the last equation that in the course of electrolysis the catholyte becomes alkaline and the ammonia which has been set free can escape into the ambient atmosphere. Further losses of ammonia are caused by its anodic oxidation to nitrogen or nitrate. Another difficulty is caused by the hydroxyl ions, which in an alkaline solution also take part in the conduction of current and are then discharged at the anode, which reduces the current efficiency. 

In the presence of an adequate amount of water, aliphatic amines are generally dealkylated by anodic oxidation. llius, a tertiary amine is successively dealkylated to a secondary amine, a primary amine and finally to ammonia, llie mechanism involves initial removal of one electron ftom the lone pair electrons of nitrogen leading to a cation radical, though a variety of mechanisms have been proposed depending on the structures of the amines and the reaction conditions. 

Non-Reversible Processes. —Reactions of the non-reversible type, i.e., with systems which do not give reversible equilibrium potentials, occur most frequently with un-ionized organic compounds the cathodic reduction of nitrobenzene to aniline and the anodic oxidation of alcohol to acetic acid are instances of this type of process. A number of inorganic reactions, such as the electrolytic reduction of nitric acid and nitrates to hydroxylamine and ammonia, and the anodic oxidation of chromic ions to chromate, are also probably irreversible in character. Although the problems of electrolytic oxidation and reduction have been the subject of much experimental investigation, the exact mechanisms of the reactions involved are still in dispute. For example, the electrolytic reduction of the compound RO to R may be represented by... 

Cyclic voltammetry in supercritical water-0.2 M NaHS04 [88] and ammonia-0.14 M CF3SO3K [88,332] of some organic compounds shows that this electroanalytical technique was applicable under these conditions. The behavior of phenazine in NH3 at —40°C and under supercritical conditions, for example, was analogous two reversible reductions were found in both cases [88]. Dimethyl carbonate has been prepared from CO and MeOH on anodic oxidation in a supercritical mixture of CO2 and MeOH [89]. 

Anodic oxidation of primary amines at platinum or carbon electrodes is not of significant preparative interest. The common products in acetonitrile are the aldehydes VI, NH4, nitrogen from the oxidation of ammonia, protonated starting material, and hydrocarbons... 

The electrochemistry of amino acids has been studied in strong acid solutions. In general, the compounds are decomposed to carboxylic acids, aldehydes, ammonia, and carbon dioxide. The results are reviewed by Weinberg [35]. The anodic oxidation mechanism has been studied in pH 10 buffer solution. Decarboxylation accompanied by C-N bond cleavage is the main reaction process [182]. The synthetically interesting Hofer-Moest decarboxylations of A/ -protected amino acids and a-amino malonic half esters under the formation of A/ -acyliminium ions is treated in the following section. 

Senanayake, G. (2005). Catalytic role of ammonia in the anodic oxidation of gold in copper-free thiosulfate solutions. Hydrometallurgy, 77(3-4), 287-293. doi 10.1016/j.hydromet.2004.12.003... 

Listed in Table 6 the data on anodic oxidation of solvated electrons in different solvents point towards the different natures of non-paramagnetic associates, on the one hand, in liquid ammonia and, on the other hand, in hexamethylphosphotriamide and methylamine. In liquid ammonia, even the fast sweep (dynamic) voltammogram does not detect the second kind of particles at that bulk concentration of solvated electrons when non-paramagnetic associates exist jjjyg, the electrons that... 

That anodic oxidation does not reveal the existence of M associates for alkali metals in liquid ammonia is consistent with the decrease in the strenght of associates in this solvent. The experimentally determined association constant for Na in hexamethylphosphotriamide equals 2.3x10 and the computed value for ammonia comes to 2.5 x 10 mol 1 To decide whether alkali metal anions exist in liquid ammonia, the oxidation of electrons must be studied at high concentrations of electrons in an intensively stirred concentrated background electrolyte solution. 

Anglada A (2011) Electro-oxidation on boron-doped diamond anodes of ammonia and organic pollutants in landfill leachate. PhD dissertation thesis, University of Cantabria, Spain... 

Lan and Tao [22] successfully applied a novel fuel cell type with an alkaline membrane to oxidize ammonia at room temperature. Compared to solid oxide fuel cells, the alkaline membrane fuel cell is less brittle and can be operated at low temperatures. As an advantage of alkaline membrane fuel cells over conventional alkaline fuel cells, no KOH-based electrolyte is needed. The researchers used two types of anodes first platinum and ruthenium deposited on carbon and sec-raid chromium-decorated nickel. The ammraiia sources were either ammraiia gas or a 35 wt% aqueous ammonia solution. 

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