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Control of microwave-generated hot spots. Part V. Mechanisms of hot-spot generation and aggregation of catalyst in a microwave-assisted reaction in toluene catalyzed by Pd-loaded AC particulates

Paper ID Volume ID Publish Year Pages File Format Full-Text
40217 45846 2013 9 PDF Available
Title
Control of microwave-generated hot spots. Part V. Mechanisms of hot-spot generation and aggregation of catalyst in a microwave-assisted reaction in toluene catalyzed by Pd-loaded AC particulates
Abstract

•The generating mechanism of hot spot was examined in the microwave's electric and magnetic fields.•The formation of hot spots was simulated by an electromagnetic field analysis and subsequently evidenced experimentally.•No formation of byproduct occurred in the organic synthesis under all microwave irradiation conditions.

Hot spots are generated when carrying out the heterogeneous Suzuki–Miyaura cross coupling reaction for the synthesis of 4-methylbiphenyl in toluene solvent in the presence of Pd/AC catalyst (AC: activated carbon; see for example parts I–IV1). Controlling these hot spots could render the microwave-assisted catalyzed reaction more effective. Accordingly, the present article examines the mechanism by which the hot spots are generated through particle aggregation observed by means of a high-speed camera; the influence of particle size was also examined. Moreover, the formation of hot spots within the spatial gap between two AC particles was simulated by an electromagnetic field analysis and subsequently evidenced experimentally. The heterogeneous Suzuki–Miyaura coupling reaction for the synthesis of 4-methylbiphenyl in toluene solvent in the presence of activated carbon (AC; no Pd) under microwave irradiation has been re-visited to ascertain what the effect of the reagents might be as to whether or not hot spots are formed. The presence of the reagents used in the synthesis of 4-methylbiphenyl did cause a firm connectivity between the activated carbon particles, which changed with the directions of the electric field and the magnetic field. The relationship between the generation of by-products and the formation of hot spots has also been considered in the synthesis of 4-methylbiphenyl in toluene solvent catalyzed by Pd/AC.

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Keywords
Microwave catalyst; Hot spots; Electromagnetic field simulation; Suzuki–Miyaura cross-coupling
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Control of microwave-generated hot spots. Part V. Mechanisms of hot-spot generation and aggregation of catalyst in a microwave-assisted reaction in toluene catalyzed by Pd-loaded AC particulates
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volumes 460–461, 10 June 2013, Pages 52–60
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us