Β-diketone Groups Research Articles

EPR investigations of structure of humic acids from compost, soil, peat and soft brown coal upon oxidation and metal uptake

Free radical concentration and theirg-values in humic acids (HA) isolated from various sources were studied by quantitative EPR technique. EPR data for HA formed during composting and natural humification processes occurring in soil, peat and brown coal are given. In more detail the EPR data were analyzed for brown coal HA under carbonization, air oxidation (150°C) as well as metal uptake (Ca(II), Zn(II), Cd(II), Hg(II), Co(II), Ni(II) and Cu(II)) and NO2 reaction. Two groups of metal complexes were distinguished on the basis of their interaction with free radicals in HA. Ca(II), Zn(II), Cd(II) and Hg(II) ions increase free radical concentration, while Co(II), Ni(II) and Cu(II) ions quench the radicals compared to the raw HA. This phenomenon can be explained either by the strong interaction of the metal ions with active centres responsible for the quinone-hydroquinone-semiquinone equilibria, and/or by the antiferromagnetic interaction between radical spins and metal d orbitals. Gaseous ammonia was found to be a very useful base easily penetrating the solid matrix of HA and strongly influencing the equilibria. β-Diketone groups present in HA react with NO2 yielding iminoxy radicals. In the HA-metal complexes these structural units are engaged in metal coordination which lowers effectiveness of the iminoxyl synthesis.

Developing the Chemistry of Novel Scandium β-Diketonates for the MOCVD of Scandium-Containing Oxides

Thin films of scandium oxide, Sc2O3, have been deposited by liquid-injection MOCVD using tetrahydrofuran solutions of the novel precursors Sc(tmod)3 (tmod = 2,2,7-trimethyloctane-3,5-dionate) and Sc(mhd)3 (mhd = 6-methylheptane-2,4-dionate). The properties of the films are compared to those of films grown using the conventional precursor Sc(thd)3 (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate). Oxide growth was observed over a wide range of substrate temperatures, from 400 °C to at least 600 °C, and the films were shown (by Auger electron spectroscopy) to be Sc2O3 with no detectable carbon impurity. The properties of the scandium β-diketonates were found to vary with the nature of the β-diketonate group and the use of the asymmetric tmod and mhd groups led to precursors with lower melting points and higher volatilities than the Sc(thd)3 source.

Novel precursors for the MOCVD of ferroelectric thin films

MOCVD is an attractive technique for the deposition of ferroelectric thin films. In order to exploit the full potential of the technique, the properties of the metalorganic precursor sometimes need to be tailored in order to optimise process parameters. In this paper we describe how the substitution of simple alkoxide groups by β-diketonate or other chelating groups can lead to precursors with improved physical properties and optimised MOCVD performance.

Chemically bonded chelates as selective complexing sorbents for gas chromatography: VI . Modification of silica with NiCl2 and CoCl2 via β-diketonate groups

Results are presented of studies of new types of packings for gas chromatography which contain nickel(II) and cobalt(II) chlorides and nickel(II) acetylacetonate chemically bonded via β-diketonate groups to a silica surface. Taking into account the ability of the metals in the chlorides and acetylacetonate to interact with compounds showing electron-donor properties, the study was performed using such adsorbates as aliphatic linear and branched hydrocarbons. The study allowed the determination of the influence of structure and configuration of adsorbate molecules on their retention and the definition of the usefulness of thus prepared packings in chromatographic analysis. The obtained results point to selectivity of the packings to the compounds which contain π electrons. Moreover, to determine the influence of the type of functional group bonded with hydrocarbon chain of a given silane on charge-transfer interactions, the obtained results were compared with those for the packings in which nickel(II), cobalt(II) chlorides and nickel(II) acetylacetonate were bonded with silica via diphenylphosphine groups.

Graft Polymerization of 1-[4-(2-Methyl-1-oxo-2-propenyl)amino]-phenyl-1,3-butanedione Polymers via Redox Initiation of Active Pendant Group with Ceric Ion

Abstract 1-[4-(2-Methyl-1-oxo-2-propenyl)amino]phenyl-1,3-butaedione (MPAPB), a vinyl monomer with a β-diketone group, was synthesized. The reaction of MPAPB with ceric ion was studied by the radical trapping technique and EPR spectrum. The homopolymer P(MPAPB) and the copolymers with methyl methacrylate (MMA), P(MPAPB-co-MMA), were prepared by a photoinitiated process using benzophenone (BP) and N,N-dimethyl-4-toluidine (DMT) as photoinitiators. The graft polymerization of acrylamide onto P(MPAPB) and P(MPAPB)-co-MMA) films initiated by ceric ion was also investigated. The formation of the grafted copolymers was revealed by grafting percentage, water absorption, XPS spectra, and scanning electron photomicrographs. To determine the exact grafting site, the effect of two model compounds as well as MPAPB on the polymerization rate of acrylamide initiated by ceric ion was studied. Based on the EPR spectrum and the kinetic study, a mechanism of the grafting reaction was proposed.

Synthesis and structure of didysprosium complexes with a tetraketone

Two novel didysprosium (Dy 2) complexes of 1,5-bis(1′-phenyl-3′-methyl-5′-pyrazolone-4′)-1,5-pentanedione (H 2L), Dy 2L 3·2H 2O and Dy 2L 3·5DMF (DMF = dimethylformamide), have been synthesized. The crystal structure of Dy 2L 3·5DMF was determined by X-ray diffraction. Crystals are triclinic, space group P1̄, with a = 16.99(1), b = 17.970(9), c = 18.28(1) Å, α = 110.36(4), β = 101.47(6), γ = 111.11(5)°, V = 4533(9) Å 3, M r = 2017.91, Z = 2, D x = 1.48 g cm −3, μ = 17.22 cm −1, F(000) = 2056, R = 0.074 with 3804 reflections used in the refinement. In the complex, each L bonds two dysprosium atoms with its two β-diketone groups. Two DMF solvent molecules bond to each dysprosium ion. The coordination number of the two dysprosium ions is eight. The eight oxygen atoms around the dysprosium ion make up a distorted square antiprism coordination polyhedron. The resonance structures of coordinated β-diketonates are also discussed. Different lanthanide ions may stabilize the specific structure.

Chemically bonded chelates as selective complexing sorbents for gas chromatography IV. Silica surfaces modified with Co(II) and Ni(II) complexes

The synthesis of some new packings for complexation gas chromatography (CGC) is proposed in this article. These packings contain acetylacetonates and hexafluoroacetylacetonates of nickel(II) and cobalt(II), which are chemically bonded to a silica gel via β-diketonate groups. The effect of the structure and the configuration of some adsorbates (olefins, cyclic and aromatic hydrocarbons) on the retention of these compounds is determined. Moreover, the usefulness of the packings in the analysis of hydrocarbons is described. The results show the good applicability of the tested packings as well as their high selectivity towards compounds which contain π-electrons.

Heterogenized polymetallic catalysts. Part I. Catalytic air oxidation of 3,5-di- t-butylphenol by Cu(II) and Fe(III) complexed to a polyphenylene polymer containing β-di-and tri-ketone surface ligands

Catalysis preparation involves the cyclic trimerization polymerization of acetylated aromatics. The polymer is coated on a high surface area support, Celite, and cured to give insoluble high molecular weight polymer. Reaction of the remaining acetyl end groups with base and methyl acetate gave β-diketone groups on the surface of the polymer. A second reaction with base and methyl acetate places β-triketones on the surface. The β-triketones can bind two metal ions in a known geometry. The chemically modified surfaces containing β-diketone and β-triketone surface ligands were reacted with Cu(OAc) 2 and FeCl 3 to give mono- and bi-metallic surface complexes. The oxidation of 3,5-di- t-butylcatechol was studied with all the surfaces. The monometallic catalysts gave only the ortho-quinone as product. The bimetallic catalysts absorbed about twice as much dioxygen as the monometallic catalysts and gave ring cleaved products. Both gave induction periods before dioxygen uptake began. With the bimetallic catalysts the dioxygen uptake stopped at about the ratio: 2 O 2 1 catechol . This is twice as much dioxygen as that required for ring cleavage so H 2O 2 may be the dioxygen reduction product rather than water. The monomeric Cu(OAc) 2 dioxygen uptake curve reached a maximum and then released gas. This could result from Cu(II) catalyzed decomposition of H 2O 2.

Use of β-diketonate anions as eluent in non-suppressed ion chromatography: 1,3-cyclohexanedionate as acidic eluent

A new low-p K a β-diketonate eluent for non-suppressed ion chromatography was developed for suppressing the dissociation of impurity anions without impairing the separation and determination of fluoride and chloride anions. It was found that 1,3-cyclohexanedionate is the preferred eluent, having a low p K a originating from the structural strain of the β-diketonate group.

SYNTHESIS AND STRUCTURE OF DINUCLEAR COMPLEXES OF TERBIUM(III) WITH 4-ACETALBISPYRAZOLONE

Abstract Two novel dinuclear complexes of terbium(III) with 1,5-bis(1′-phenyl-3′-methyl-5′-pyrazolone-4′)-1,5-pentanedione (H2L), Tb2L3·6H2), Tb2L3·SDMF, have been synthesized. The crystal structure of Tb2L3 · 5DMF was determined by X-ray diffraction methods. Crystals are triclinic, space group P 1 with α = 16.957(5), b = 17.877(7), c = 18.269(2)A, α = 110.35(2), β = 101.29(2), γ = 111.00(2)°, V = 4511(6)A3, Mr = 2010.76, Z = 2, Dx = 1.48g cm−3, μ = 16.45 cm−1, F(000) = 2,052, R = 0.058 with 6574 reflections used in refinement. In the complex, L acts as a bridging ligand and bonds two terbium atoms with its two β-diketone groups. Each terbium ion bonds to two DMF solvent molecules. The coordination number of the two terbium ions is eight. The eight oxygen atoms around the terbium make a distorted square antiprismatic coordination polyhedron.

Polymer-Supported Lewis Acid Catalysts. V. Complexes of Titanium Chloride or Stannic Chloride with Poly (βDiketone) Carrier

Abstract A polymer carrier containing (β-diketone groups was synthesized by a free radical polymerization of methacrylacetone monomer and combined with titanium tetrachloride or stannic chloride in chloroform to form two very stable complexes containing 19.5 and 18.3% CI which are equivalent to 1.40 mmol TiCl4 complex beads and 1.28 mmol SnCl4; complex beads, respectively. The two complexes showed good catalytic activity in many organic reactions such as acetalation, ketal formation, and esterification. The catalysts can be reused at least 8 times without losing their activity in organic reactions.

Effect of γ‐irradiation and temperature on the structure of metal chloride‐treated poly(vinyl alcohol)

AbstractThe infrared and ultraviolet spectra of poly(vinyl alcohol) (PVA) treated with ferric chloride and zinc chloride were recorded. Careful examination of the infrared spectra revealed that these treatments cause significant changes in the crystallinity of PVA, particularly in the case of the treatment with ZnCl2. The results showed that exposure of untreated and FeCl3‐treated PVA to 12 or 28 Mrads results in no observable changes in their ultraviolet and infrared spectral features, whereas exposure of ZnCl2‐treated PVA at the same dosages, results in the appearance of an absorption band at 1595 cm−1 corresponding to β‐diketone groups. It was also found that γ‐irradiation of ZnCl2‐treated PVA produces a remarkable change in its crystallinity. Moreover, the effect of heat on the spectral features of the ZnCl2‐treated PVA was discussed. It was found that the treatment of PVA with ZnCl2 helps in oxidative degradation of PVA.

Investigation on the synthesis and characterization of rare earth metal‐containing polymers. II. Fluorescence properties of Eu3+–polymer complexes containing β‐diketone ligand

AbstractEuropium(III) chelates of dibenzoylmethane (DBM) (1) and β‐diketone‐containing polymers, i.e., poly(p‐benzoylacetylstyrene) (2) and poly(aryl β‐diketone) (3), were prepared. In the polymer 2 the β‐diketone moiety is attached to the phenyl ring, and for polymer 3 the β‐diketone group is incorporated in the linear chain. The chelate structures were confirmed by measuring IR spectra, TGA, and DTA. The fluorescence emission intensity was measured on fine powder samples. For the composite samples of Eu(DBM)4 in polystyrene, the fluorescence intensity was found to increase linearly with increasing Eu content. However, for Eu coordination polymers, the intensity reached a maximum at Eu3+ content as small as 1 wt % and remained constant on further increasing the Eu3+ content. When the fluorescence intensities of Eu complexes were compared under the same conditions, namely, 1 wt % Eu, at which Eu–2 and Eu–3 show nearly maximum intensity, the order was found to be Eu–1 > Eu–2 > Eu–3. These phenomena were accounted for by the differences in the coordination number of the Eu complexes.

Dicarbonyl allyl derivatives of molybdenum and tungsten containing β-diketonate substituents

A number of complexes of the type M(CO) 2(η 3-allyl)(diket)L (where M is Mo or W, diket is a β-diketonate group and L is pyridine, tetrahydofuran or acetonitrile) have been prepared and characterized by elemental analysis and IR and NMR spectroscopy. These complexes apparently adopt an octahedral configuration similar to related neutral species but spectroscopic data indicate an equilibrium between two conformers probably due to rotation of the allyl groups.

Carbonyl (η 3-allyl) anions of molybdenum and tungsten

Anionic complexes of the type [M(CO) 2(diket)(η 3-allyl)Cl] − (where M is Mo or W and diket is a β-diketonate group) are readily prepared by the addition of allyl chloride to [M(CO) 4(diket)] − anions. NMR measurements indicate an equilibrium between two conformers due to rotation of the allyl groups. [M(CO) 5(OC(=O)R)] − anions also react with allyl chloride to form η 3-allyl complex anions. Some structural aspects of both the diketonate and carboxylate derivatives are discussed.

Preparation of .BETA.-diketone resins and an application in separation of 59Fe and 60Co.

Two macroreticular resins containing β-diketone groups were prepared and their adsorptivity for nine metal ions was investigated by batch operation. Although these resins were highly selective for Fe (III) in acidic region (pH 1-4), no significant affinity was observed for Cd (II), Co (II), Cu (II), Mg (II), Mn (II), Ni (II), Zn (II), and U (VI). The β-diketone resin prepared from styrene-divinylbenzene copolymer and diketene was applicable to the separation of 59Fe and 60Co by a column operation.

Nuclear magnetic resonance study of keto-enol tautomerism in polymeric ?-dicarbonyl compounds

1. Carbon-chain polymers with β-diketone and β-keto ester functional groups in the side chains have been synthesized. 2. The tautomeric equilibrium of the polymeric β-dicarbonyl compounds polymethacryloylacetone and poly(vinyl acetoacetate) and low-molecular models of these polymers has been studied. The effect of the macromolecular nature of the polymeric β-diketones on the tautomeric equilibrium is expressed as a significant difference between their thermodynamic equilibrium parameters and those of the low-molecular analog.

Investigations on Organoantimony Compounds : XIII. Benzene solvent shifts in the PMR spectra of isomeric Hexacoordinate Dichlorodiarylantimony(V) β-Diketonates

PMR benzene solvent shifts Δδ [δ(CCl4)δ(C6D6)] have been measure for β-diketonate group protons of isomeric hexacoordinate dichlorodiarylantimony(V) β-diketonates. The observed solvent shifts are interpreted on the basis of a non-specific tangential approach of the benzene molecules to the electron-deficient sites of the solute. An inductive substituent constant σ1 of 0.48 has been deduced for the 2,2′-biphenylylene group.PMR benzene solvent shifts Δδ of the various protons in the two isomers of p-Tol2SbCl2Acac are not markedly different and do not allow a conclusion concerning the geometry of the isomers, which is, however, easily assigned on the basis of aromatic ring current effects.

Reactions between Fulvic Acid and Cu2+-Montmorillonite

AbstractShaking of water-soluble fulvic acid with Cu2+-montmorillonite at pH 2·5 increased the interlamellar spacing from 10·0 to 15·1 A. The spacings were measured at ≈ 0% relative humidity. The extent of interlayer adsorption decreased with increase in pH. Differential thermal analysis and thermogravimetric examinations showed that in addition to interlayer adsorption, fulvic acid was also retained on external clay surfaces. The FA was held so tightly by the Cu2+-clay that > 3/4 of the total amount adsorbed, including degradation products formed from it, resisted decomposition even when heated to 1000°C. I.R. spectra showed that β-diketone groups in fulvic acid reacted with Cu2+ in or on the clay to form acetylacetonate-type chelates. Indications were obtained that the mechanism postulated for the FA-Cu2+-clay interaction may also apply to reactions between FA and montmorillonite saturated with other di- and trivalent metal ions. Reactions of FA in aqueous solutions with metal ions in the presence of clays differ from those in the absence of clay. Montmorillonite appears to affect the conformation of the fulvic acid polymer in a way that favours reactions between C=O groups and metal ions, a type of reaction that has so far not been observed in aqueous solutions in the absence of clay.

Organothallium compounds. VII. β-Diketonatobis(pentafluorophenyl)-thallium(III) compounds and their coordination derivatives

The complexes (C6F5)2TlX [X = MeCOCHCOMe (acac), CF3COCHCOMe (tfac), CF8COCHCOCF3 (hfac), PhCOCHCOMe (bzac), PhCOCHCOPh (dbm), or quinolin-8- olate (oxinate or ox)], have been prepared by reactions between bromobis(pentafluorophenyl)thallium(III) and the appropriate sodium or thallous β-diketonates or sodium quinolin-8-olate, and react with equimolar amounts of 1,10-phenanthroline (phen) or 2,2?-bipyridyl (bipy) to give the complexes (C6F5)2- (phen or bipy)TlX (X = acac, tfac, or hfac), (C6F5)2(phen)TlX (X = bzac, dbm, or ox), but not (C6F5)2(bipy)TlX (X = bzac, dbm, or ox). On reaction with triphenyl- phosphine oxide or triphenylarsine oxide, the complexes (C6F5)2(Ph3PO or Ph3AsO)-TlX (X = acac, tfac, hfac, or dbm) and (C6F5)2Ph3AsOTl(ox) have been obtained. From conductance and molecular weight measurements and spectroscopic data, the complexes (C6F5)2TlX (except X = ox), (C6F5)2(Ph3PO or Ph3AsO)TlX, and (C6F5)2(phen or bipy)TlX, are considered to be monomeric with chelated β-diketonate or oxinate groups, and hence to contain four-, five-, and six-coordinate thallium respectively, whereas (C6F5)2Tl(ox) is considered to have an associated structure with bridging oxinate groups.