Study of uric acid oxidation reaction products in medium of ammonia or primary amines

This work is considered in more detail the most important stage of obtaining one of the promising heteroatomic polycyclic compounds 3,7,10-trioxo-2,4,6,8,9,11-hexaaza[3.3.3]propellane (THAP). THAP is a potential compound for creating high-energy substances due to the presence of six nitrogen atoms in the structure and tight packing. Uric acid is the starting compound in the THAP synthesis chain. When it is oxidized by sodium persulfate or potassium ferrocyanide, 1,5-diaminoglycoluril is formed, from which the propellane structure is formed by the tricyclization reaction. This work expanded the range of oxidants for the conversion of uric acid to 1,5-diaminoglycoluril. It was found that 1,5-diaminoglycoluril was formed with a yield of 29 % when using equimolar proportions of uric acid and KMnO4. When using MnO2 in a ten times more excess, the yield of 1,5-diaminoglycoluril was 38 %. The article also presents the results of a study of the interaction of uric acid with some amines. The reaction of interaction of uric acid with benzylamine was studied in more detail, the reaction products of which were 4-benzylimino-5-benzylaminoallantoin, 4- benzylimino-1-benzylamino-allantoin and 4-benzyliminoallantoin. Based on the synthesis of 4- benzyliminoallantoin, a number of promising derivatives of 4-iminoallantoin were obtained, namely 4- ethyliminoallantoin, 4-propyliminoallantoin, 4-i-propyliminoallantoin, 4-n-butyliminoallantoin, 4-i- butyliminoallantoin, 4-tert-butyliminoallantoin.

Evaluation of performance characteristics of nano TiO2 and TiO2-ZnO composite for DSSC applications and electrochemical determination of potassium ferrocyanide using cyclic voltammetry

Nanoparticles of TiO2 and TiO2-ZnO composite (2:1 molar ratio) were synthesized utilizing the sol-gel and solution combustion approaches, respectively. Scanning electron microscopic, energy dispersive x-ray, x-ray diffraction, UV-visible spectroscopy, and Brunauer–Emmett–Teller analysis were employed to characterize the synthesized nanoporous TiO2 and the composite of TiO2-ZnO nanoparticles. Fabrication of dye-sensitized solar cells (DSSCs) was carried out by incorporating the synthesized nanoporous materials coating on the photoanodes using the doctor blade technique. Nano TiO2 and the composite of TiO2-ZnO were also analyzed using cyclic voltammetry test, and their performance was compared for the electrochemical detection of potassium ferrocyanide. The composite of TiO2-ZnO exhibited better electrocatalytic activity in comparison with the pure TiO2 nanoparticles. The fabricated DSSCs by employing nano TiO2 particles and TiO2-ZnO composite as the semiconductor photoanode materials were compared for photovoltaic performance. The DSSC fabricated with TiO2 nanoparticles exhibited better photovoltaic performance with an efficiency of 2.22% and a current density of 4.152 mA cm−2 than that fabricated with TiO2-ZnO composite with an efficiency of 0.0022% and a short circuit current density of 0.014 mA cm−2.

Recovery of Gold from Ore with Potassium Ferrocyanide Solution under UV Light

In this study, potassium ferrocyanide, a nontoxic cyanide precursor in dark and diffuse reflection environment, was applied as reagent for the leaching of gold. The free cyanide ions could gradually release from potassium ferrocyanide solution under the ultraviolet light. Orthogonal leaching experiments were performed in gold ore to analyze the effect of solution pH, potassium ferrocyanide dosage, and temperature in a potassium ferrocyanide solution system under UV light. Response surface methodology (RSM) was applied to explore the role of potassium ferrocyanide in gold leaching; optimized results showed that the gold recovery reached 67.74% in a high-alkaline environment at a 12.6 pH, 3.8 kg/t potassium ferrocyanide dosage, 62 °C, and irradiance of 10 mW·cm−2. The gold leaching kinetics were monitored by quartz crystal microbalance with dissipation (QCM-D) of potassium ferrocyanide solution. The results indicate that the gold extraction process could be divided into two stages: adsorption and leaching, and a rigid adsorption layer formed on the reaction surface. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis of the gold sensor surface after leaching reaction showed that –C≡N appears on the gold sensor surface, and the gold is oxidized to form AuCN complexes.