Classical chemical sciences
More than 85 % yields of ten substituted 2-benzylidene-1-tosylhydrazines have been prepared by thionyl chloride assisted condensation of 1-tosylhydrazine and substituted benzaldehydes in room temperature. They are characterized by their physical constants, analytical, and spectroscopic data. The antimicrobial activities of these hydrazines were evaluated by Bauer-Kirby disc diffusion method.
Keywords: 2-benzylidene-1-tosylhydrazines; IR and NMR spectra; antimicrobial activities
The improved syntheses of 5-(indol-3-yl)-5-hydroxypyrimidine-2,4,6(1H,3H,5H)-trione (1), 5-(5-methylfuran-2-yl)-5-hydroxypyrimidine-2,4,6(1H,3H,5H)-trione (2), 5-(5-N,N-dimethylhydrazonylfuran-2-yl)-5-hydroxypyrimidine-2,4,6(1H,3H,5H)-trione (3), 5-(4-N,N-di-methyl-aminophenyl)-5-hydroxypyrimidine-2,4,6(1H,3H,5H)-trione (4a), and 5-(4-N,N-diethylaminophenyl)-5-hydroxypyrimidine-2,4,6 (1H,3H,5H)-trione (4b) from alloxane in mild conditions were reported. The structure of 5-(indol-3-yl)-5-hydroxypyrimidine-2,4,6(1H,3H,5H)-trione (1) has been determined by XRD study.
Keywords: alloxan; indol; 2-methylfurane; 5-(indol-3-yl)-5-hydroxypyrimidine-2,4,6(1H,3H,5H)-trione; 5-(5-methylfuran-2-yl)-5-hydroxypyrimidine-2,4,6(1H,3H,5H)-trione; synthesis; structure
The oxidation of organic sulfides by quinolinium chlorochromate (QCC) resulted the formation of the corresponding organic sulfoxides. These reactions are first order ones with respect to QCC. A Michaelis-Menten type kinetics was observed with respect to the reactants. The reaction is catalyzed by p-toluene sulfonic acid (TsOH). The oxidation was studied in nineteen different organic solvents. An analysis of the solvent effect on Swain's equation showed that the both cation- and anion-solvating powers of the solvents play important roles. The correlation analyses of the rate of oxidation of thirty-four sulfides were done in terms of various single and multiparametric equations. In the reactions of aryl methyl sulfides, the best correlation could be obtained with Charton's LDR and LDRS equations. The oxidation reactions of alkyl phenyl sulfides exhibited an excellent correlation in terms of Pavelich-Taft equation. The negative values of polar reaction constants indicate an electron-deficient sulfur center in the rate- determining step. The proposed reaction mechanism involves the formation of a sulphenium cation intermediate in a slow step
Keywords: Correlation analysis, halochromate, kinetics, mechanism, sulfide, oxidation
Sols prepared by chelation of titanium n-butoxide, Ti(OC4H9)4, with ethyl acetoacetate, C6H10O3, in various ratios were slowly hydrolyzed, and the obtained gels were investigated using Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis. The gels were thermally treated at 350 °C, and the products were investigated using X-ray diffraction, N2 gas adsorption–desorption isotherms and diffuse reflectance UV–Vis spectroscopy. Photocatalytic activity assessment was obtained through degradation process of methylene blue under UV light. From the results obtained, the relationships between gel structure and titania crystallite size, specific surface area, bandgap, and photocatalytic activity, as the most relevant parameters, were discussed. The alkoxide modification affected the gel structure, as well as the properties of the final material. However, the sample prepared from unmodified Ti-n-butoxide yielded the most favorable properties.
Keywords: Nanocrystalline anatase; photocatalytic activity; bandgap; ethyl acetoacetate; chelating agent
3-Chloro-1H-indole-2-carbaldehyde (4) was synthesized and converted into Schiff base derivatives (5a-5c). Compounds 5a-5c were reacted with chloroacetyl chloride to give 2-azetidinone derivatives (6a-6c). Compound 4 reacts with active methylene group containing compounds, hydrazine and phenylhydrazine derivatives undergoing a condensation reaction. Compound 4 was reacted with ethyl chloroacetate derivatives to give N-alkylated indole Schiff bases which undergoing cyclization reaction using chloroacetyl chloride to afford azetidinone derivatives.
Keywords: chloroacetic acid; anthranilic acid; Schiff bases; lactams
Materials and environmental chemistry
The peculiarities of electrochemical preparation of composite materials (intermetallides, polymetallic powders: CoTaMo, CoNbMo, YMoMn, YAl) from various compounds (CoF2, Nb2O5, YF3, Na2MoO4, MnCl2, AlF3, Na3AlF6) against the background of halide metals: KCl, K, Na/Cl, K/Cl, F were studied. X-ray phase and chemical analyses of obtained materials were carried out.
Keywords: electrochemical synthesis; composite materials; potentiostat electrolysis; halide melts
Industrial and engineering chemistry, biotechnology
Photocatalytically active titanium dioxide is used as a white pigment in cosmetics; however, it may promote a certain degree of sebum decomposition on the skin exposed to ultraviolet radiation (sunlight). In this work, titanium dioxide was shaken with various condensed phosphate solutions to synthesize a novel white pigment for cosmetic applications. Titanium dioxide particles were added to various solutions at a P/Ti molar ratio of 1:1, and then shaken in water at 80ºC for 1 h. The chemical composition, powder properties, photocatalytic activity, color phase, and smoothness of the produced powders were studied. The obtained materials exhibited the XRD peaks of titanium dioxide, although the peak intensities were weakened by the formation of a surface layer of titanium phosphate. These samples consisted of particles with sub-micrometer sizes, and the photocatalytic activity of the powders was reduced sufficiently to prevent the degradation of sebum on the skin. The suitable condensed phosphate for condensed phosphoric acid treatment of titanium oxide was sodium triphosphate from the whiteness and smoothness of powders.
Keywords: Titanium dioxide; condensed phosphate; photocatalytic activity; particle size
Good process control has often been criticized for the economic viability of large-scale production of several commercial products. In this work, the production of biodiesel from microalgae is investigated. Successful implementation of a model-based control strategy requires the identification of a model that properly captures the biochemical dynamics of microalgae, yet is simple enough to allow its implementation for controller design. This paper explores the biodiesel production in a class of continuous culture under heterotrophic conditions via closed-loop operation. A mathematical model adapted from Surisetty et al. (2010) that describe the growth of microalgae in a heterotrophic culture is studied via dynamic analysis. This model is extended to the continuous operation where bifurcation analysis was carried out for the determinate the qualitative model behavior and to analyze feasible operating conditions. This project is focused on the on the use of a mixture of two substrates that are continuously fed into the reactor chamber, and the continuous fermentation process is described by an unstructured mathematical model with a product inhibition on cell growth. In addition, we present the design of a nonlinear control law contains a class of bounded type feedback of the named control error in order to regulate the substrate concentration at maximum value to lead the lipids-diesel concentration indirectly. Lipid productivity in continuous culture was 0.276 g L-1 d-1 via a closed loop (increase of 31.5 %) over that of the continuous mode in open loop. Finally, numerical experiments proved the satisfactory performance of the proposed methodology in comparison with a linear PI controller.
Keywords: Biodiesel; nonlinear controller; bifurcation analysis; heterotrophic culture