Microwave-induced catalytic transformation of 2-tert-butylphenol at low temperatures

Kurfürstová, Jana; Hájek, Milan

doi:10.1163/1568567041570357

Cited by 13 publications

(7 citation statements)

References 12 publications

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“…Deactivation of noble metal-supported heterogeneous catalysts can occur by a) sintering of metal crys- [ 45] In the present case, degradation of the polymeric phase can be neglected. In addition, formation of poisoning side products has never been reported for this kind of transfer hydrogenations.…”

Section: Reusability Studies and Aging A) Reusability Studymentioning

confidence: 99%

Palladium(0) Nanoparticles on Glass‐Polymer Composite Materials as Recyclable Catalysts: A Comparison Study on their Use in Batch and Continuous Flow Processes

et al. 2008

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Palladium particles were generated by reduction of palladate anions bound to an ion exchange resin inside microreactors. The size and distribution of the palladium particles differed substantially depending on the degree of cross-linking and the density of ion exchange sites on the polymer/ glass composites, the latter parameter having a larger influence than the former. The polymer phase of the composite materials was used for the loading with clusters composed of palladium particles which are 1 to 10 nm in diameter. The reactivity and stability of six different palladium-doped polymer/glass composite samples for transfer hydrogenations was investigated both under conventional and microwave heating in the batch mode as well as under continuous flow conditions using the cyclohexene-promoted transfer hydrogenation of ethyl cinnamate as a model reaction. Regarding the heating method it was found that catalysts that are composed of larger metal particles perform better under microwave irradiating conditions whereas samples with smaller particle sizes perform better under conventional heating. Comparing batch experiments with flow-through experiments the latter technique gives better conversion. Reusability was better in microwave heated experiments than in traditional heating.

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Section: Reusability Studies and Aging A) Reusability Studymentioning

confidence: 99%

Palladium(0) Nanoparticles on Glass‐Polymer Composite Materials as Recyclable Catalysts: A Comparison Study on their Use in Batch and Continuous Flow Processes

et al. 2008

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“…However, there is one paper by Kurfürstová and Hajek 12 with a very wide range of temperatures. In this paper they studied the microwave induced catalytic transformation of 2-tert-butylphenol over a temperature range from…”

Section: Methodsmentioning

confidence: 99%

“…Several studies will be discussed to seek evidence for the predicted signature for this effect. One paper 12 was found that appears to show the predicted behavior of the reaction rate. A discussion of the impact of non-adiabatic excitations i s included in Section 5.…”

Section: Introductionmentioning

confidence: 95%

Microwave Effect in Chemical Reactions

Bowen¹,

Kanis²,

Daniel³

et al. 2014

JCB

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Time dependent perturbation theory predicts no change in the electronic state probability amplitudes of molecules unless the energy of the applied electromagnetic field matches an electronic energy level difference. Therefore, microwaves should have no non-thermal effect on chemical reactions. However, at low frequencies the oscillating potentials are essentially classical and the relevant question is whether the electronic molecular states evolve adiabatically or non-adiabatically. Time varying potentials can mix excited states into the instantaneous adiabatic ground state as the expectation of the energy changes in response to the potential. This mixing yields a non-zero excited state pr o ba bi l i t y a m p l i t u d e s c n (t). Measurements of these excited states, for example, by reactant collisions, may collapse the instantaneous ground state wave function onto the excited state with a probability |cn (t)| 2 . This nonadiabatic probability o p e n s a new channel for chemical reactions in addition to the usual thermal A r r h e n i u s probability. The temperature dependence of the reaction rate from these two channels will exhibit the microwave effects primarily at low temperatures. At high temperatures the Arrhenius pr oba bili ti es w i l l dominate and the microwave effects may be negligible. Most precise laboratory a s s e s s m e n t s of non-thermal mi c r ow a v e effects appear to have been at high temperatures. Several experiments are reviewed and one is found to have a wide enough temperature range to exhibit the predicted f o r m . Our results also suggest that m i c r o w a v e couplings could induce reactions different from those weighted by the thermal probabilities .

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“…As a result, this method allows more microwave energy to be introduced into the reaction system for a faster reaction. Although only a few studies dealt with this subject, most of them observed enhanced reaction rates through two methods: cooling with a stream of compressed air [13, 14] or with a microwave transparent cooling liquid (such as liquid N 2 , solid CO 2 in hexane, or cryogenic fluid) [15, 16]. The latter cooling method enables the reaction to be conducted at very low temperatures, which is especially favorable for improving the stability of biomolecules and achieving high enantioselectivity.…”

Section: Introductionmentioning

confidence: 99%

Microwave-induced inactivation of DNA-based hybrid catalyst in asymmetric catalysis

Zhao

Shen

2016

International Journal of Biological Macromolecules

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DNA-based hybrid catalysts have gained strong interests in asymmetric reactions. However, to maintain the high enantioselectivity, these reactions are usually conducted at relatively low temperatures (e.g. < 5 °C) for 2–3 days. Aiming to improve the reaction’s turnover rate, we evaluated microwave irradiation with simultaneous cooling as potential energy source since this method has been widely used to accelerate various chemical and enzymatic reactions. However, our data indicated that microwave irradiation induced an inactivation of DNA-based hybrid catalyst even at low temperatures (such as 5 °C). Circular dichroism (CD) spectra and gel electrophoresis of DNA suggest that microwave exposure degrades DNA molecules and disrupts DNA double-stranded structures, causing changes of DNA–metal ligand binding properties and thus poor DNA catalytic performance.

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Microwave-induced catalytic transformation of 2-tert-butylphenol at low temperatures

Cited by 13 publications

References 12 publications

Palladium(0) Nanoparticles on Glass‐Polymer Composite Materials as Recyclable Catalysts: A Comparison Study on their Use in Batch and Continuous Flow Processes

Palladium(0) Nanoparticles on Glass‐Polymer Composite Materials as Recyclable Catalysts: A Comparison Study on their Use in Batch and Continuous Flow Processes

Microwave Effect in Chemical Reactions

Microwave-induced inactivation of DNA-based hybrid catalyst in asymmetric catalysis

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