Acetylacetone System Research Articles

Electrospray Ionization Mass Spectrometric Study of the Gas-Phase Coordination Chemistry of Be2+ Ions with 1,2- and 1,3-Diketone Ligands.

Electrospray ionization mass spectrometry (ESI MS) is a powerful technique for the study of coordination complexes because of its ability to analyze solution systems involving very low concentrations of metal complexes. In this work, the coordination chemistry of Be ions with a selection of well-known 1,3-diketone and related 1,2-diketone ligands has been investigated using ESI MS. With acetylacetone (Hacac), a range of acac-containing ions is observed, including [Be(acac)2H]+, [Be(acac)(MeOH) n]+ ( n = 1, 2), and polynuclear species such as the dinuclear [Be2(acac)3]+ and trinuclear [Be3O(acac)3]+. Density functional theory calculations indicate that the latter species has a central Be3(μ3-O) core, with each Be chelated (as opposed to being bridged) by an acac ligand. The effect of changing the substituents on 1,3-diketone was explored by an investigation of mixtures of Be2+ with other 1,3-diketones such as dibenzoylmethane (Hdbm), where the [Be(dbm)2H]+ ion showed a lesser tendency to undergo fragmentation and aggregation processes. Comparisons with the corresponding aluminum acetylacetone system were also made. In contrast, mixtures of Be2+ and the 1,2-diketones diacetyl and phenanthrenequinone showed poor metal-ligand interactions. Be2+ interacted with the 1,2-diketone benzil [PhC(O)C(O)Ph], forming the [Be(benzil) n]2+ ( n = 2-4) ions. The synthesis (from BeCl2) and X-ray structures of the dibenzoylmethanato (dbm) complex Be(dbm)2 and the benzil complex [BeCl2(benzil)] are also reported.

Particles size effects of single domain CoFe2O4 on suspensions stability

Single domain magnetic CoFe2O4 nanoparticles with spinel structure were prepared by the coprecipitation method. Particles with size of 16, 20, 40 and 60nm were synthesized by sintering the precursor at 500, 600, 800 and 900°C, respectively. The magnetic hysteresis measurement of CoFe2O4 particles showed that particles were single domain particles with similar saturation magnetization (∼300emu/cm3) at room temperature. The zeta potential study of suspensions (CoFe2O4–acetylacetone system) with various particle sizes showed the suspension systems had similar zeta potential values (∼40mV). The effects of magnetic particle size on the suspension stability characterized by electrophoretic deposition yields and sediment volumes were studied. The suspension stability decreased with an increase in particle size and a flocculation threshold of particle radius a was found at 30nm. A suspension stability theory approaching to the phenomenon was established. The theory based on the DLVO theory was developed by introducing an extra magnetic interaction force. Dormann model was adopted, in which the magnetic interactions of two spherical nanoparticles were investigated in terms of dipole–dipole interactions. Compared to DLVO, suspension's physical parameters not only zeta potential ζ and the Debye length 1/κ, but also particles' radius a brought about stable to flocculation transition in the theory.

The adsorption of divalent metal cations on mesoporous silicate MCM-41

MCM-41 is a synthetic, mesoporous silicate material, which currently has limited use as an industrial catalyst. This material is considered to have good potential for adsorption/separation applications due to its regular hexagonal structure, uniform pore distribution, large surface area and large pore volume. In order to enhance the adsorption of metal ions on MCM-41, a metal ion chelating agent, acetylacetone is added and the capacity of the adsorbent for three divalent metal cations in aqueous solutions; Cu(II), Ni(II) and Co(II) determined. Adsorption isotherms for these metal ions are presented, along with adsorption selectivity with respect to pH. Metal ion adsorption results are compared with published data for solvent extraction systems utilising pure acetylacetone and acetylacetone in benzene. It was found that the MCM-41/acetylacetone system produced equal or better metals removal in comparison to solvent extraction methods for some of the metal species tested. Further, the pH of maximum adsorption is shifted in the MCM-41 system compared with the solvent extraction case, thus presenting the possibility of processing under different conditions.

Speciation of the vanadium(III)–acetylacetone system in 3.0 M KCl ionic medium at 25°C

A study of the H+-acetylacetone (acac, HC) and H+–V3+-acetylacetone systems using emf(H) and UV–Vis measurements in 3.0 M KCl ionic medium at 25°C is presented here. As the initial case, the acetylacetone pK a value was determined under similar experimental conditions as reported a few years ago, finding very similar values. Subsequently, in the study of the H+–V3+-acetylacetone system, the stability constants of [VC]2+, [VC2]+, VC3, [OHVC]+, OHVC2, [(OH)2V2C]3+ and [(OH)2V2C2]2+ complexes were determined by emf(H) measurements, and by means of UV–Vis measurements the respective values of [VC]2+, [VC2]+, VC3 and [OHVC]+ species, which are the most abundant in this system. The data analysis was carried out using the NERNST, FONDO, and SPEFO versions of the least-squares program LETAGROP. Some extra-thermodynamic relationships about the stability order of the VII, VIII, and VIV-acetylacetone complexes were obtained by ab initio calculations.

Isobaric Vapor−Liquid Equilibria for the Binary Systems of Acetic Acid + Isopropenyl Acetate, Acetic Acid + Acetylacetone, and Water + Acetylacetone

Isobaric vapor−liquid equilibrium (VLE) data for the binary systems of acetic acid + acetylacetone and water + acetylacetone have been determined at 101.3 kPa, and those for the acetic acid + isopropenyl acetate system have been determined at 60.0 kPa. A minimum boiling azeotrope has been found in the water + acetylacetone system. Azeotropic behavior has not been found for the other two systems. The nonideality of the vapor phase has been considered by using the Hayden−O’Connell equation. Thermodynamic consistency has been tested for all VLE data. The experimental data have been correlated satisfactorily by the NRTL, UNIQUAC, and Wilson models.

Synthesis of Silver Complexes in DMSO–HX and DMSO–HX–Ketone Systems

Comparative analysis of the oxidizing and complexing properties of the DMSO–HX (X = Cl, Br, I) and DMSO–HX–ketone (X = Br, I; the ketone is acetone, acetylacetone, or acetophenone) systems toward silver was performed. The reaction products are AgX (X = Cl, Br, I), [Me3S+]AgnX–m(n= 1, 2; m= 2, 3; X = Br, I) and [Me2S+CH2COR]AgX–2(R = Me, Ph; X = Br, I). The composition of the obtained complexes depends on both the DMSO : HX ratio and the nature of HX, as well as on the methods used to isolate solid products from the solution. It was noted that the formation of the [Me2S+CH2COMe]AgBr–2complex in the Ag0–DMSO–HBr–acetylacetone system occurs with cleavage of the acetylacetone C–C bond and follows a specific reaction course. The optimum conditions for production of the silver compounds in the title systems are determined.

ChemInform Abstract: Formation of Titania Nanotubes with High Photo‐Catalytic Activity.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Formation of Titania Nanotubes with High Photo-Catalytic Activity

Abstract Titania nanotubes with high photo-catalytic activity were synthesized in laurylamine hydrochloride / tetraisopropyl orthotitanate modified with acetylacetone system. Formation of nanotubes was confirmed by transmission electron microscope images. These titania nanotubes had crystal structure of anatase and showed high photo-catalytic activity, i.e., the activity is about three times higher than Degussa-P-25 and higher than ST-01.

On the role of the ground state Tb(III)/acetylacetone complex in sensitized emission of Tb(III) in ethanol solution

The Tb(III)-acetylacetone system in ethanol solution has been studied by spectroscopic methods. The formation of a Tb(III)/acetylacetone (1:1) complex in the ground state has been proved and its stability constant determined,K=(0.97±0.06)·104dm3mol−1. The role of this complex in the spectrofluorimetric determination ofLn(III) ions in the presence of acetylacetone has been discussed.

WATER ADDUCTS ON ACETYLACETONE, DIETHYLDITHIOCARBAMATE AND DITHIZONE CHELATES IN WATER AND CHLOROFORM

The number of water molecules associated with several metal chelates in water and then after being extracted into chloroform has been determined. A relationship between the number of water molecule adducts in the aqueous phase and the charge to volume ratio was determined for the acetylacetone system and an empirical equation developed.

Double oscillations in reaction in bromate-manganese(II, III)-acetylacetone system

The Belousov--Zhabotinskii oscillating chemical reactions with the participation of acetylacetone, a representative of the class of 8-diketones with an activated methylene group as the reducing agent, have several characteristic features. In a study of the oscillating reaction in the bromate--manganese(ll)--acetylacetone system it was found [1-4] that: i) the reaction proceeds without an induction period, 2) after consumption of the reducing agent and cessation of regular oscillations, chaotic oscillations of the measured characteristics are observed, 3) with simultaneous action of other reducing agents (malonic acid, ethyl acetonate) together with acatylacetone, acetylacetone is the first to enter the reaction, and only after its complete consumption does the next reducing agent react, rThe last fact, as well as spectrophotometric investigations [I], confirm the special role of the complexation between the manganese ions and acetylacetone. In [5, 6] it has already been shown that in the oscillating process in the Belousov--Zhabotinskii systems, complexation between the catalyst ions and the reducing agent plays an important role. To explain the role of this complexation, in the present work we carried out a comparative study of the parameters of the oscillating chemical reactions, with manganese(Ill) sulfate, manganese(II) acetylacetonate, and manganese(Ill) acetylacetonate serving as components.

Oscillations chimiques du système BrO/Ce4+/acétylacétone. Communication préliminaire

AbstractTemporal chemical oscillations occurring in the BrO3−/Ce4+/acetylacetone system have been investigated by three different methods: potentiometry, calorimetry and NMR. spectrometry. In spite of the analogy between acetylacetone and malonic acid, this periodic reaction seems to be rather different from the famous Belousov‐Zhabotinsky reaction.

Proton magnetic resonance studies of some metal complexes of β-diketones and organophosphorus compounds in carbon tetrachloride

Proton magnetic resonance evidence in carbon tetrachloride medium is given for the formation of the keto hydrates of hexafluoroacetylacetone(HHFA), thenoyltrifluoroacetone(HTTA), benzoyltrifluoroacetone(HBTA), and trifluoroacetylacetone(HTFA). The keto hydrates of HHFA and HTTA, with structures III and I, respectively, have been isolated in the crystalline state and analyzed, whereas the keto hydrates of HBTA and HTFA have not been isolated and are more difficult to obtain. No keto hydrate of acetylacetone in carbon tetrachloride is formed. The strength of electron-release increases in the order: trifluoromethyl group in HHFA, thenoyl group in HTTA, phenyl group in HBTA, and methyl group in HTFA, and this order is paralleled by the decrease in the ability to form keto hydrates. Since no ternary zinc complex with the phosphine oxide exists in the acetylacetone system, no synergism or destruction of synergism can occur, and this is in agreement with data obtained from solvent extraction studies using 65Zn.