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Acetylacetonate

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Krzysztof Matyjaszewski – One of the best experts on this subject based on the ideXlab platform.

  • Reversible-Deactivation Radical Polymerization of Methyl Methacrylate and Styrene Mediated by Alkyl Dithiocarbamates and Copper Acetylacetonates
    Macromolecules, 2013
    Co-Authors: Yaozhong Zhang, Kristin Schroder, Yungwan Kwak, Pawel Krys, Tomislav Pintauer, Rinaldo Poli, Aurélie Morin, Krzysztof Matyjaszewski

    Abstract:

    Reversible-deactivation radical polymerization (RDRP) of methyl methacrylate (MMA) and styrene (St) was successfully mediated by copper(II) Acetylacetonate, [Cu(acac)2], or copper(II) hexafluoroAcetylacetonate, [Cu(hfa)2], in conjunction with 1-cyano-1-methylethyl diethyldithiocarbamate (MAN-DC) or 2-(N,N-diethyldithiocarbamyl)ethyl isobutyrate (EMA-DC) initiators/transfer agents in the absence of additional reducing agents. Linear first-order kinetic plots were obtained for the polymerization of MMA in the presence of [Cu(hfa)2] or [Cu(acac)2] and MAN-DC. [Cu(hfa)2] provided better control than [Cu(acac)2] for the polymerization of MMA, leading to PMMA with narrow molecular weight distribution, Mw/Mn ∼ 1.1. Polymerization of St was successfully carried out with either MAN-DC or EMA-DC in the presence of [Cu(hfa)2], also resulting in polymers with low Mw/Mn values. In the absence of alkyl dithiocarbamates or copper Acetylacetonates, the polymerizations resulted in only trace amounts of polymers or polymers with high values of Mw/Mn. Thus, the combination of alkyl dithiocarbamates and copper(II) Acetylacetonates provides a convenient way to prepare well-controlled PMMA and PSt. NMR analysis of low-MW polymers reveals the presence of DC groups as chain ends. DFT calculations show that DC group transfer from a H-MMA-DC model of the growing chain to the Cu(II) complexes is energetically accessible and more favorable than Br atom transfer, thus rationalizing the need for the Cu(II)/dithiocarbamate combination for successful control and suggesting that the process takes place by reversible DC group transfer involving a CuII/CuIII couple. Attempts to synthesize complexes [Cu(acac)2(DC)] and [Cu(hfa)2(DC)], in combination with DFT calculations, suggest that these complexes are thermodynamically unstable relative to the bis(diketonate)copper(II) and dithiuram disulfide, but this does not preclude the involvement of the Cu(III) species as a spin trap in RDRP controlled by DC group transfer

  • reversible deactivation radical polymerization of methyl methacrylate and styrene mediated by alkyl dithiocarbamates and copper Acetylacetonates
    Macromolecules, 2013
    Co-Authors: Yaozhong Zhang, Kristin Schroder, Yungwan Kwak, Pawel Krys, Aurelie N Morin, Tomislav Pintauer, Rinaldo Poli, Krzysztof Matyjaszewski

    Abstract:

    Reversible-deactivation radical polymerization (RDRP) of methyl methacrylate (MMA) and styrene (St) was successfully mediated by copper(II) Acetylacetonate, [Cu(acac)2], or copper(II) hexafluoroAcetylacetonate, [Cu(hfa)2], in conjunction with 1-cyano-1-methylethyl diethyldithiocarbamate (MAN-DC) or 2-(N,N-diethyldithiocarbamyl)ethyl isobutyrate (EMA-DC) initiators/transfer agents in the absence of additional reducing agents. Linear first-order kinetic plots were obtained for the polymerization of MMA in the presence of [Cu(hfa)2] or [Cu(acac)2] and MAN-DC. [Cu(hfa)2] provided better control than [Cu(acac)2] for the polymerization of MMA, leading to PMMA with narrow molecular weight distribution, Mw/Mn ∼ 1.1. Polymerization of St was successfully carried out with either MAN-DC or EMA-DC in the presence of [Cu(hfa)2], also resulting in polymers with low Mw/Mn values. In the absence of alkyl dithiocarbamates or copper Acetylacetonates, the polymerizations resulted in only trace amounts of polymers or polymer…

Burak Atakan – One of the best experts on this subject based on the ideXlab platform.

  • Thermal stability, sublimation pressures and diffusion coefficients of some metal Acetylacetonates
    Surface & Coatings Technology, 2007
    Co-Authors: M. Aslam Siddiqi, Rehan A. Siddiqui, Burak Atakan

    Abstract:

    Metal Acetylacetonates are often used as precursors for the deposition of oxides in CVD or ALE experiments. The thermal stability and the vapour/sublimation pressures of such compounds are of fundamental importance for reproducible depositions. We have started a program to study the long term thermal stability, sublimation pressures and the diffusion coefficients of organometallic compounds. The latter are needed for the calculation of the Sherwood and Lewis numbers used to describe mass transfer process. In a recent publication [M. A. Siddiqi, B. Atakan, Thermochim. Acta 452 (2007) 128.] we demonstrated a method for the evaluation of diffusion coefficients of less volatile substances in gas mixtures by combining the experimental thermogravimetric measurements with accurate sublimation pressure data (e.g. from Knudsen effusion method). In the present communication the results for aluminium(III) Acetylacetonate, chromium(III) Acetylacetonate, iron(III) Acetylacetonate, manganese(III) Acetylacetonate and nickel(II) Acetylacetonate are presented. The last three of these show decomposition at low temperatures. Aluminium(III) Acetylacetonate and chromium(III) Acetylacetonate evaporate without residuals and hence their sublimation pressures and binary diffusion coefficients at various temperatures are reported for the first time.

Seiichiro Kagei – One of the best experts on this subject based on the ideXlab platform.

  • Diffusion coefficients of metal Acetylacetonates in supercritical carbon dioxide
    Fluid Phase Equilibria, 2010
    Co-Authors: Chang Yi Kong, Masato Nakamura, Toshitaka Funazukuri, Seiichiro Kagei

    Abstract:

    Abstract Binary diffusion coefficients, D12, of the metal Acetylacetonates, palladium(II) Acetylacetonate and cobalt(III) Acetylacetonate, were measured from 308.2 to 343.2 K over the pressure range from 9 to 40 MPa at infinite dilution in supercritical carbon dioxide using the chromatographic impulse response method. The effects of pressure, temperature, density, and viscosity on D12 values were examined. It was observed that the D12 values of palladium(II) Acetylacetonate and cobalt(III) Acetylacetonate were larger than those of lipids with similar molecular weights, such as arachidonic acid and monoolein, respectively. Furthermore, the measured D12 data of each metal Acetylacetonate were well correlated by the hydrodynamic equation D12/T as a function of carbon dioxide viscosity.