Catalytic effect of supported metal ion complexes on the induced oxidative degradation of pyrocatechol violet by hydrogen peroxide

Kinetics of the oxidative degradation of pyrocatechol violet dye (PCV) [2-[(3,4-dihydroxyphenyl)(3-hydroxy-4-oxocyclohexa-2,5-dien-1-ylidene) methyl]-benzenesulfonic acid] by H(2)O(2) catalyzed by supported transition metal complexes have been studied. The reaction was followed by conventional UV-vis spectrophotometer at lambda(max)=440 nm in a buffer solution at pH 5.1. The supports used were silica gel and cation exchange resins (Dowex-50W, 2 and 8% DVB), while the complexes were [Cu(amm)(4)](2+), [Cu(en)(2)](2+), [Cu(ma)(4)](2+), [Co(amm)(6)](2+), and [Ni(amm)(6)](2+) (amm=ammonia, en=ethylenediamine, and ma=methylamine). The reaction exhibited first-order kinetics with respect to [PCV] and [H(2)O(2)]. The reactivity of the catalysts is correlated with the redox potential of the metal ions, the type of support, and the amount of supported complexes. The rate of the reaction increases with increasing pH and the addition of NaCl. Addition of SDS and CTAB showed inhibiting effects. The reaction is enthalpy-controlled as confirmed from the isokinetic relationship. A reaction mechanism involved the generation of free radicals as an oxidant has been proposed.     

Preparation and characterization of polyaniline films in the presence of N-phenyl-1,4-phenylenediamine

The chemical oxidation of aniline to form polyaniline (PANI) films was made in the presence of N-phenyl-1,4-phenylenediamine (PPDA) in aqueous hydrochloric acid medium. The PANI films were monitored by using the quartz crystal microbalance (QCM) technique. The effect of PPDA and its concentration on the film formation was investigated. It was found that PPDA decreases the yield of the PANI film, the induction period and the depletion time of the polymerization. However, the growth rate of the film formation was found to increase by increasing PPDA concentration. These results were justified by measuring the UV-VIS absorption spectra for the in situ PANI films and the in situ UV-VIS absorption spectra for the polymer in the bulk during the polymerization. The conductivity for the PANI films at different concentrations of PPDA was measured. Also, the IR spectra, X-ray and the thermal gravimetric analysis for the PANI powder formed in the bulk in the presence of PPDA were measured and discussed.     

Green and Facile Synthesis of New 3-(Phenylallylideneamino)indeno[1,2-d]imidazoles

A green and facile strategy has been proposed for the synthesis of previously unknown 3a,8a-dihydroxy-3-[(3-phenylprop-2-en-1-ylidene)amino]-2-sulfanylidene-2,3,3a,8a-tetrahydro-1H-indeno[1,2-{und}]imidazol-8-one and 3a,8a-dihydroxy-3-[(3-phenylprop-2-en-1-ylidene)amino]-1,3,3a,8a-tetrahydroindeno[1,2-d]-imidazole-2,8-dione in excellent yields by condensation of cinnamaldehyde thiosemicarbazone and semicarbazone, respectively, with ninhydrin in boiling dioxane. The reaction is clean, simple, and free of work-up and column chromatography.

     

Radiation synthesis of copper sulphide/poly(vinyl alcohol) nanocomposites films: an efficient and reusable catalyst for p-nitrophenol reduction

ABSTRACT

Copper sulphide nanoparticles (CuS NPs) were in situ synthesised via irradiation process, using Poly (vinyl alcohol) (PVA) as host polymeric matrices. The as-prepared CuS/PVA nanocomposite films were characterised by X-ray diffraction (XRD) spectroscopy, ultraviolet-visible (UV-VIS) spectroscopy, Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). Both UV-VIS spectra and X-ray diffraction patterns confirmed the formation of CuS nanoparticles. The FTIR spectrum indicates the coordination between CuS nanoparticles and the OH groups of the PVA chains. The TEM image showed that the obtained CuS nanoparticles have spherical shape, monodispersed and uniform particle size distribution. The CuS/PVA nanocomposite film was successfully applied in the reduction of p-nitrophenol into p-aminophenol as a catalyst using NaBH₄ as reducing agent. The catalytic test indicates that CuS/PVA nanocomposite film has high activity for the conversion of P-NP into P-AP and effectively recycled and reused for several times.     

Synthesis Properties and Characterization of Di Cyclopentadienyl Vanadium Bis Dialkyl and Alkylene Dithiophosphate Complexes

The reaction of dichloro bis cyclopentadienyl vanadium with O,O dialkyl and alkylene dithiophosphoric acids proceed in 1:2 molar ratio in refluxing benzene to yield di cyclopentadienyl vanadium bis O,O dialkyl and alkylene dithiophosphates, [Cp 2 V(S 2 P(OR) 2 ) 2 ], where R = Et, Pr i , Pr n , Bu i , Ph and [Cp 2 V (S 2 POGO) 2 ] where G = CMe 2 CMe 2 , CH 2 CEt 2 CH 2 , CH 2 CMe 2 CH 2 . These complexes are semi solids or solids soluble in common organic solvents. Elemental analysis, molecular weight determination, magnetic susceptibility, UV-vis spectrophotometer, IR, 1 H, 13 C, and 31 P NMR spectra indicate a hexa coordinated octahedral structure.     

CH(A2Delta) Formation in hydrocarbon combustion: the temperature dependence of the rate constant of the reaction C2H + O2--> CH(A2Delta) + CO2

The temperature dependence of the rate constant of the chemiluminescence reaction C2H + O2 --> CH(A) + CO2, k1e, has been experimentally determined over the temperature range 316-837 K using pulsed laser photolysis techniques. The rate constant was found to have a pronounced positive temperature dependence given by k1e(T) = AT(4.4) exp(1150 +/- 150/T), where A = 1 x 10(-27) cm(3) s(-1). The preexponential factor for k1e, A, which is known only to within an order of magnitude, is based on a revised expression for the rate constant for the C2H + O(3P) --> CH(A) + CO reaction, k2b, of (1.0 +/- 0.5) x 10(-11) exp(-230 K/T) cm3 s(-1) [Devriendt, K.; Van Look, H.; Ceursters, B.; Peeters, J. Chem. Phys. Lett. 1996, 261, 450] and a k2b/k1e determination of this work of 1200 +/- 500 at 295 K. Using the temperature dependence of the rate constant k1e(T)/k1e(300 K), which is much more accurately and precisely determined than is A, we predict an increase in k(1e) of a factor 60 +/- 16 between 300 and 1500 K. The ratio of rate constants k2b/k1e is predicted to change from 1200 +/- 500 at 295 K to 40 +/- 25 at 1500 K. These results suggest that the reaction C2H + O2 --> CH(A) + CO2 contributes significantly to CH(A-->X) chemiluminescence in hot flames and especially under fuel-lean conditions where it probably dominates the reaction C2H + O(3P) --> CH(A) + CO.