Practical Microwave Synthesis for Organic Chemists

Kappe, C. Oliver; Dallinger, Doris; Murphree, S. Shaun

doi:10.1002/9783527623907

Cited by 317 publications

(448 citation statements)

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“…MAOS methods using oven microwave oven reactor and a DeanStark trap apparatus attachment is the renewable of this research. It has an efficient direct thermal heating which needed only 66 minutes using a power of 300 W. This method gave the advantages from the point of view of using quite low frequency to generate dipole movement of reaction mixtures directly [17][18]20]. Dielectric heating process of microwaveassisted reaction was derived from NMP as solvent used in this reaction which has a dielectric constant (e) of 34.22 [20].…”

Section: Synthesis Of Pesmentioning

confidence: 99%

The Microwave-assisted Synthesis of Polyethersulfone (PES) as A Matrix in Immobilization of Candida antarctica Lipase B (Cal-B)

Widhyahrini

Handayani

Wahyuningrum

et al. 2017

Bull. Chem. React. Eng. Catal.

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Candida antarctica lipase B (Cal-B) has been widely used in the hydrolysis reaction. However, it has some weaknesses, such as: forming of the heavy emulsion during the process, which is difficult to resolve and has no reusability. Therefore, it needs to be immobilized into a suitable matrix. One of the suitable supporting materials is polyethersulfone (PES) and its synthesis becames the objective of this paper. The PES was synthesized via a polycondensation reaction between hydroquinone and 4,4'-dichlorodiphenylsulfonein N-methylpyrrolidone (NMP) as solvent using Microwave Assisted Organic Synthesis (MAOS) method at170 °C for 66 minutes using an irradiation power of 300 watt. The synthesized PES was characterized by FTIR and 1 H-NMR (500 MHz, DMSO-d6). Then the PES membrane was prepared from 20% of the optimized mixtures of PES, PSf (polysulfone), and PEG (polyethylene glycol) dissolved in 80% NMP. The Cal-B was immobilized on the PES membrane by mixing it in a shaker at 30 °C and 100 rpm for 24 h using phosphate buffered saline (PBS). The identification of the immobilized Cal-B was done by using FTIR-ATR spectroscopy and SEM micrographs. The results of Lowry assay showed that the 'Cal-B immobilized' blended-membrane has a loading capacity of 91 mg/cm 2 in a membrane surface area of 17.34 cm 2 . In this work, the activity of immobilized Cal-B was twice higher than the native enzyme in p-NP (p-Nitrophenolpalmitate) hydrolyzing. The results indicated that the synthesized PES showed a good performance when used as a matrix in the immobilization of Cal-B.

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Section: Synthesis Of Pesmentioning

confidence: 99%

The Microwave-assisted Synthesis of Polyethersulfone (PES) as A Matrix in Immobilization of Candida antarctica Lipase B (Cal-B)

Widhyahrini

Handayani

Wahyuningrum

et al. 2017

Bull. Chem. React. Eng. Catal.

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“…All of the considerations below will involve the quantum mechanical eigenstates Ψ n with energy E n of the unperturbed molecular Hamilton H 0 and the effect of a time dependent perturbation V(t) on the state |Ψ(t)⟩ (1) where c n (t) is the probability amplitude for the Ψ n . The probability P n (t) of finding the system in state Ψ n at time t is given by the absolute value squared of the probability amplitude P n (t) = |c n (t)| 2 .…”

Section: Introductionmentioning

confidence: 99%

“…Many chemists over the last several years have begun to use microwave ovens as a chemical reaction platform and frequently have reported [1][2][3][4][5][6][7] that several different reactions seem to run faster, with higher yields, or more completely than conventionally heated chemical reactions. These observations have led many to wonder if there is an effect of the microwaves in addition to the heating of the solvent than can enhance the reaction rate of the chemical reactions that are being studied.…”

Section: Introductionmentioning

confidence: 99%

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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“…Moreover, combining milli-reactor operation and microwave heating as an alternative energy source, allows the accurate control of temperatures and residence times in chemical processes. This consequently enhances control of reactor performance in terms of conversion and product selectivity [8][9][10]. In particular, regarding the twelve principles of green chemistry, process intensification and novel process windows provide many options by which to meet sustainable processing criteria [11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Microwave-assisted Cu-catalyzed Ullmann ether synthesis in a continuous-flow milli-plant

Benaskar

Patil

Engels

et al. 2012

Chemical Engineering Journal

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The combination of milli-scale processing and microwave heating has been investigated for the Cu-catalyzed Ullmann etherification in fine-chemical synthesis, providing improved catalytic activity and selective catalyst heating. Wall-coated and fixed-bed milli-reactors were designed and applied in the Cu-catalyzed Ullmann-type C-O coupling of phenol and 4-chloropyridine. In a batch reactor the results show clearly increased yields for the microwave heated process at low microwave powers, whereas high powers and catalyst loadings reduced the benefits of microwave heating. Slightly higher yields were found in the Cu/ZnO wallcoated as compared to the Cu/TiO 2 fixed-bed flow-reactor. The benefit here is that the reaction occurs at the surface of the metal nanoparticles confined within a support film making the nano-copper equally accessible. Catalyst deactivation was mainly caused by Cu oxidation and coke formation; however, at longer process times leaching played a significant role. Catalyst 2 activity could partially be recovered by removal of deposited by-product by means of calcination. After 6 h on-stream the reactor productivities were 28.3 and 55.1 kg prod /(m R 3 •hr)for the fresh Cu/ZnO wall-coated and Cu/TiO 2 fixed-bed reactor, respectively. Comparison of single-and multimode microwaves showed a three-fold yield increase for single-mode microwaves. Control of nanoparticles size and loading allows to avoid high temperatures in a single-mode microwave field and provides a novel solution to a major problem for combining metal catalysis and microwave heating. Catalyst stability appeared to be more important and provided two-fold yield increase for the CuZn/TiO 2 catalyst as compared to the Cu/TiO 2 catalyst due to stabilized copper by preferential oxidation of the zinc. For this catalyst a threefold yield increase was observed in single-mode microwaves which, to the best of our knowledge, led to a not yet reported productivity of 172 kg prod /(m R 3 •hr) for the microwave and flow Ullmann C-O coupling.

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Practical Microwave Synthesis for Organic Chemists

Cited by 317 publications

References 0 publications

The Microwave-assisted Synthesis of Polyethersulfone (PES) as A Matrix in Immobilization of Candida antarctica Lipase B (Cal-B)

The Microwave-assisted Synthesis of Polyethersulfone (PES) as A Matrix in Immobilization of Candida antarctica Lipase B (Cal-B)

Microwave Effect in Chemical Reactions

Microwave-assisted Cu-catalyzed Ullmann ether synthesis in a continuous-flow milli-plant

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