Microwaves in Chemistry

Slocombe, Daniel; Porch, Adrian

doi:10.1109/jmw.2020.3029337

Cited by 6 publications

(2 citation statements)

References 77 publications

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“…For more than 10 years, publications focused on teaching chemistry with microwave oven applications have appeared in the scientific literature [33,34,36,[38][39][40][49][50][51]. In addition to motivational experiments with the microwave oven such as investigation of the effect of microwaves on filter paper, basic tasks implementing microwaves in synthesis of organic compounds have recently been reported [52][53][54][55]. These educational laboratory tasks include, for example, the acetylation of salicylic acid with acetic anhydride to form acetylsalicylic acid (i.e.…”

Section: Theoretical Partmentioning

confidence: 99%

Microwave-Aided Reactions of Aniline Derivatives with Formic Acid: Inquiry-Based Learning Experiments

Mycak¹,

Doležal

Bílek

et al. 2022

Chemistry-Didactics-Ecology-Metrology

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The synthesis of amides belongs to traditional experimental tasks not only in organic chemistry exercises at universities but also at chemically focused secondary schools or in special practices at general high schools. An example of such a synthesis may be the preparation of acetanilide via reaction of aniline with acetic acid or acetic anhydride. However, both of these reactions are associated with a rather long reaction time and certain hazards that limit their straightforward use in pedagogical practice. Conveniently, the reaction of aniline with acetic acid may be significantly optimised if it is performed under solvent-free conditions in the presence of microwaves, which reduces considerably the reaction time and provides very good yield, compared to traditional heating by a heating nest. In this study, the main pedagogical aim of the experimental design is elucidation of the influence of the structure of the amines on the course of the reaction with formic acid through inquiry-based learning. Specifically, the proposed experiments consist in investigation of the chemical yield achieved in microwave assisted reactions of aniline and its derivatives with formic acid in such a way that is adequate for constructive learning of undergraduate chemistry students. The selected series of amines involves aniline, 4-methoxyaniline, 4-chloroaniline, and 4-nitroaniline. In accordance with the chemical reactivity principles, students gradually realise that the influence of the substituent is reflected in the reaction yield, which grows in the following order: N-(4-nitrophenyl)formamide ˂ N-(4-chlorophenyl)formamide ˂ N-phenylformamide ˂ N-(4-methoxyphenyl)formamide. Therefore, the results of the experiments enable students to discover that stronger basicity of the amine increases the yield of the amide. In order to deepen the students’ chemical knowledge and skills, the concept of the experiments was transformed to support inquiry-based student learning. The proposed experiments are intended for experimental learning in universities educating future chemistry teachers, but they may be also utilised in the form of workshops for students at secondary schools of a general educational nature.

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Section: Theoretical Partmentioning

confidence: 99%

Microwave-Aided Reactions of Aniline Derivatives with Formic Acid: Inquiry-Based Learning Experiments

Mycak¹,

Doležal

Bílek

et al. 2022

Chemistry-Didactics-Ecology-Metrology

View full text Add to dashboard Cite

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“…Microwave testing has several distinct attributes, such as no need for couplants or transducers bonded onto the surface, good penetration in dielectrics and no ionising hazards [8]. Microwave testing has been applied in varied fields, like aerospace engineering [9], mechanical engineering, food engineering [10], [11], petroleum engineering, chemical engineering [12], civil engineering, forestry and medical science. Taking the last type as an example, research has been conducted on the detection of skin cancer [13], breast cancer [14], neck diseases [15], blood glucose [16] and colonoscopy [17].…”

Section: Introductionmentioning

confidence: 99%

Non-destructive testing of human teeth using microwaves: a state-of-the-art review

2023

Journal of Electrical Engineering

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Tooth diseases including dental caries, periodontitis and cracks have been public health problems globally. How to detect them at the early stage and perform thorough diagnosis are critical for the treatment. The diseases can be viewed as defects from the perspective of non-destructive testing. Such a defect can affect the material properties (e.g., optical, chemical, mechanical, acoustic, density and dielectric properties). A non-destructive testing method is commonly developed to sense the change of one particular property. Microwave testing is one that is focused on the dielectric properties. In recent years, this technique has received increased attention in dentistry. Here, the dielectric properties of human teeth are presented first, and the measurement methods are addressed. Then, the research progress on the detection of teeth over the last decade is reviewed, identifying achievements and challenges. Finally, the research trends are outlined, including electromagnetic simulation, radio frequency identification and heating-based techniques.

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Designing Heterogeneous Catalysts for Microwave Assisted Selective Oxygenation

Sun,

Hayward,

Barter

et al. 2024

ChemCatChem

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Microwave dielectric heating is an emerging technology in heterogeneous catalysis. However, catalyst design in this field is not as well developed as when conventional heating is used. In this study the selective oxidation of propene to acrolein has been used as a model reaction to understand the how the properties of bismuth mixed metal oxide catalysts can be tuned for use in microwave assisted catalysis. The role of the dielectric properties, that are crucial to enable the catalyst to be heated in the microwave electric field, were determined using cavity perturbation methods. Catalysts with a very high loss tangent reached high temperatures leading to combustion products, whereas materials with a low loss tangent could not be heated and were inactive. Bi2MoO6 and BiVO4 both showed promising performance during an initial screening and were investigated further. For Bi2MoO6, a partial substitution of molybdenum with vanadium resulted in the formation of Bi1‐X/3V1‐xMoxO4, with a decrease in particle size and dielectric loss tangent, and the highest rate of acrolein production was found when x= 0.6 at 15 W microwave power. Higher microwave power resulted in thermal runaway which decreased the activity of the catalyst.

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Microwaves in Chemistry

Cited by 6 publications

References 77 publications

Microwave-Aided Reactions of Aniline Derivatives with Formic Acid: Inquiry-Based Learning Experiments

Microwave-Aided Reactions of Aniline Derivatives with Formic Acid: Inquiry-Based Learning Experiments

Non-destructive testing of human teeth using microwaves: a state-of-the-art review

Designing Heterogeneous Catalysts for Microwave Assisted Selective Oxygenation

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