Thermodynamics for the hydrogenation of dimanganese decacarbonyl

Klingler, R. J.; Rathke, J. W.

doi:10.1021/ic00031a021

Cited by 27 publications

(18 citation statements)

References 3 publications

(5 reference statements)

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“…The purity of the substrates methyl paraben and ethyl paraben was checked by 1 H NMR spectroscopy after dissolution in CDCl 3 (Bruker Avance 400 MHz with 0.5 WB, equipped with a 5-mm TBI probe with z gradient, running a standard Bruker-supplied pulse sequence). The spectral measurements showed only very minor levels of impurities.…”

Section: Methodsmentioning

confidence: 99%

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Combined Online Spectroscopic, Calorimetric, and Chemometric Analysis: Reaction Enthalpy Determinations in Single and Parallel Reactions

2009

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Calorimetry and signal processing: Vibrational spectroscopies, heat-flow microcalorimetry, and multivariate analysis are combined to decouple the reaction enthalpies of parallel reactions [picture: see text]. This methodology allows the evaluation of reaction enthalpy from complex systems without recourse to conventional kinetic modeling. Simultaneous in situ/online spectroscopy and heat-flow measurements as well as multivariate analyses are performed, apparently for the first time, to determine heats of reaction for single and parallel reactions. Two different vibrational spectroscopy techniques, namely Raman and FTIR spectroscopy, are used in conjunction with flow-through TAM III microcalorimetry. With respect to the spectroscopic analysis, the reaction spectra are first analyzed to determine the pure-component spectra and the corresponding concentrations without recourse to external calibration. With respect to the calorimetric analysis, a soft modeling approach is employed to determine the heats of reaction without recourse to any conventional kinetic models. This combined approach is implemented to determine the extents of reaction as well as the corresponding heats of reaction at 298.15 K and 0.1 MPa for a) the hydrolysis of acetic anhydride (single reaction) and b) the hydrolysis of methyl paraben and ethyl paraben in alkaline solution (both single and parallel reactions). In the latter case, the heat-flow contributions from the two simultaneous reactions are successfully decoupled. Taken together, these results demonstrate proof of concept for the present approach. The newly developed methodology appears to be quite general and particularly useful for investigating complex reaction systems. This is particularly true for multiple simultaneous reactions and reactions where the detailed kinetic expressions are not available, or cannot be easily determined. The use of extents of reaction is also very helpful where there is high variability in reaction rates, that is, due to the presence of impurities, changes in catalyst activity, or concentrations, temperature, and pH.

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Section: Methodsmentioning

confidence: 99%

“…Chemical reactions are typically accompanied by the absorption or liberation of heat (the exception is thermoneutral transformation [1] ). This thermal effect, at fixed pressure, is defined as the heat of reaction or the reaction enthalpy.…”

Section: Introductionmentioning

confidence: 99%

Combined Online Spectroscopic, Calorimetric, and Chemometric Analysis: Reaction Enthalpy Determinations in Single and Parallel Reactions

2009

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“…Toroid rf coils and toroid cavities provide excellent signal-to-noise ratio compared to conventional Helmholtz or saddle coils, and very high rf amplitudes on the order of 100 kHz can be reached. In toroid cavity autoclaves [18,24], pressures of up to 300 bar and temperatures of up to 250°C are attainable, making it possible, e.g., to investigate in situ reaction dynamics of homogeneously catalyzed reactions, such as the cobalt-catalyzed hydroformylation process [25][26][27][28].…”

Section: Toroid Probesmentioning

confidence: 99%

Design and application of robust rf pulses for toroid cavity NMR spectroscopy

Skinner

Braun

Woelk

et al. 2011

Journal of Magnetic Resonance

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We present robust radio frequency (rf) pulses that tolerate a factor of six inhomogeneity in the B₁ field, significantly enhancing the potential of toroid cavity resonators for NMR spectroscopic applications. Both point-to-point (PP) and unitary rotation (UR) pulses were optimized for excitation, inversion, and refocusing using the gradient ascent pulse engineering (GRAPE) algorithm based on optimal control theory. In addition, the optimized parameterization (OP) algorithm applied to the adiabatic BIR-4 UR pulse scheme enabled ultra-short (50 μs) pulses with acceptable performance compared to standard implementations. OP also discovered a new class of non-adiabatic pulse shapes with improved performance within the BIR-4 framework. However, none of the OP-BIR4 pulses are competitive with the more generally optimized UR pulses. The advantages of the new pulses are demonstrated in simulations and experiments. In particular, the DQF COSY result presented here represents the first implementation of 2D NMR spectroscopy using a toroid probe.

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“…In a related activity, thermodynamics were determined for the hydrogenation of dimanganese decacarbonyl [39].…”

Section: (32-3)mentioning

confidence: 99%