Vietnam Journal of Chemistry

Using the G3B3 method, we constructed the portions of potential energy surface containing low-energy pathways of HCCO + NO2reaction. These show that only two separate reaction pathways are possible leading to HCNO + CO2and HCO + NO + CO.

In this study, organoclays were synthesized by placing dimethyl dioctadecyl ammonium (DMDODA) cation onto bentonites.  The structure of modified bentonites was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), chemical analysis, thermal analysis and FT-IR spectra. The intercalation of the DMDODA cation increased the interlamellar distances from 15.6Å (Na-bentonites) to 40.57Å. The effect of temperature, pH, time and amount of quaternary ammonium salt on the distance layer of organoclays was addressed.

The synthesis of new ether derivatives of curcumin (4a-c) via in situ two - step reaction and ester derivatives of of curcumin (6a-b) was performed in moderate to high yields. The structure of synthesized derivatives was confirmed by IR, 1H-NMR and 13C-NMR spectra.

The interaction  of K[Pt(Saf)Cl3] (Saf: safrole) with AgNO3, SnCl2, KOH  and ethanol-water solutions was investigated. For the first time, a dinuclear chelate ring complex [Pt2Cl2(Saf-1H)2], in which deprotonated safrole is bound up with platinum(II) both at benzene carbon and at ethylenic double bond of the side chain was isolated and characterized by elemental, thermal analysis, ESI MS, IR- and NMR spectroscopy.

The 0.01 M phenol + H2SO4 0.5 M oxydation process on SnO2-Sb2O5/Ti anode electrode is researched by cyclic voltammetry and elctrochemical impedance methods. The results show that phenol oxydation potential is 1.2 V/SCE (less than water oxydation potential). This is favourable condition for the phenol oxydation reaction with a high efficiency. The phenol decomposed efficiency at 10 mA/cm2 imposed current during 7 hours is 39% but the COD removal (%) is 62.7%.

In this paper, the influence of dispersion methods on dispersion degree of nanoclay in epoxy matrix was studied. The dispersion degree of nanoclay was evaluated by various, method, namely XRD, viscosity measurement and TEM techniques. The results showed that high speed stirring (2000 rpm) may create the interchalated structure of nanoclay in matrix: the d-spacing of I28E increased from 23.33 Å to 38.02 Å, and for I30E from 26.71 Å to 40.12 Å after 10 hours stirring. The combination of high speed stirring with ultra sonication still more increases the dispersion efficiency: the d-spacing of both studied nanoclay was increasing almost 2 times. The presence of nanoclay increased fracture toughness of nanocomposites compared to neat epoxy. Keywords: Dispersion, nanoclay, epoxy resin.

Friedelan-3b-ol (1), b-sitosterol (2), oryzanol-C (3), 2,4,6-trimethoxyacetophenone (4), 3,4,3’-tri-O-methylellagic acid (5), scoparone (6), hopenone B (7), and tetradecane-1,2-diol (8) were isolated from the leaves and stems of Euphorbia tithymaloides L. (Euphrobiaceae) collected in northern Vietnam. Their structures were determined by spectroscopic analysis. Keywords: Euphorbia tithymaloides, Pedilanthus tithymaloides, Euphorbiaceae, triterpenoid, phenolic compound.

In this study, nanocomposite Fe3O4–alginate has been prepared by so-called two step method. The crystal structures and morphologies of as-synthesized nanopaticles (NPs) were characterized X-ray diffraction, and scanning electron microscopy. The surface states of Fe3O4-alginate NPs were characterized by Fourier transform infrared spectra. a-Fe2O3 was fabricated from the nanocomposite Fe3O4-alginate by heat treatment in air atmosphere at 600 oC and their gas sensing properties were investigated. The performance of the a-Fe2O3 in the detection of toxic and flammable gases such as carbon oxide, ammonia, liquefied petroleum gas, ethanol, and hydrogen was evaluated. The Fe2O3 based gas sensors exhibited high sensitivity and a response time of less than a minute to analytic gases. Keywords: Fe2O3, Fe3O4, gas sensor, alginate.

The technique of ion exchange for separation of lactic acid from fermentation broth is used in our study. The ion exchange resin used is a strong anionic resin, a product of Jacobi Carbons Company, Italy (trade name is Resinex A-4). The process at laboratory scale is realized in a chromatographic column with dimensions d x h = 10mm x 110mm which contains 6 g of anionic resin. Two solvents used are distilled water and methanol. The HPLC analysis shows a good efficacy of distilled water.

Diethyl ferrocene is an important additive used in producing missile fuel. It plays role as a combustive catalyst in fuel component, it can enhance combustive rate of fuel from 2 to 3 times when its content is used from 1.5 to 2.5 wt%. In this paper, we report some results in synthesizing diethyl ferrocene. Its structure was confirmed by IR, 1H-, 13C-NMR and MS spectra. Its specifications were also investigated. Keywords: Diethyl ferrocene, ethylcyclopentadiene.