Catalysts microwave-assisted synthesis

Desai B, Kappe CO (2004) Microwave-Assisted Synthesis Involving Immobilized Catalysts. 

Pirola C, Bianchi CL, Michele AD, Diodati P, Boffito D, Ragaini V (2010) Ultrasound and microwave assisted synthesis of high loading Fe-supported Fischer-Tropsch catalysts. Ultrason Sonochem 17 610-616... 

Siamaki, A.R., et ah, Microwave-assisted synthesis of palladium nanoparticles supported on graphene A highly active and recyclable catalyst for carbon-carbon cross-coupling reactions. Journal of Catalysis, 2011. 279(1) p. 1-11. 

De la Hoz et al. have studied the microwave-assisted synthesis of substituted coumarins by the condensation of phenol, 1,3-dihydroxybenzene/l,3,5-trihydroxy-benzene and propynoic/propenoic acids55. The examples illustrate that the application of heterogeneous supported catalysts can eliminate the production of acidic waste streams, associated with conventional Lewis acid catalysts. This synthetic approach constitutes an interesting alternative to the Pechman reaction (Scheme 3.34). 

In addition to fluorous catalysis, the preparation of fluorous catalyst itself can benefit from microwave-assisted synthesis. The Wood group reported the preparation of rhodium perfluorobutyramide (Rh2(pfm)4), a catalyst for... 

Tu and co-workers [112, 115] elaborated a green protocol for the synthesis of polysubstituted indeno[ 1,2-6]-quinolines 69 via condensation of an aldehyde, 1,3-indanedione and an enaminone using p-toluene sulfonic acid as the catalyst in water under microwave irradiation. A series of 23 indeno[l,2-6]quinolines 69 was generated in excellent yields. The same authors have also described the microwave-assisted synthesis of these compounds in acetic acid as solvent (Scheme 53). 

Mirza-Aghayan, M., Ghassemzadeh, M., Hoseini, M., Bolourtchian, M. Microwave-assisted synthesis of the tetradentate Schiff-bases under solvent-free and catalyst-free condition. Synth. Commun. 2003, 33, 521-525. 

Li, F., Wang, Q., Ding, Z., Tao, F. Microwave-Assisted Synthesis of Diaryl Ethers without Catalyst. Org. Lett. 2003, 5, 2169-2171. 

Microwave-assisted synthesis of a guar-g-polyactylamide (G-g-PAA) has also been reported [80]. The reactions were performed in a domestic microwave oven. Graft copolymerization of the guar gum (GG) with acrylamide (AA) under the action of microwave irradiation in the absence of any radical initiators and catalyst resulted in grafting yields comparable with redox (potassium persulfate-ascorbic acid) initiated by conventional heating but in a very short reaction time. Grafting efficiency up to 20% was further increased when initiators and catalyst were used under microwave irradiation conditions. Maximum grafting efficiency achieved under MW conditions was 66.66% in 0.22 min, compared with 49.12% in 90 min by the conventional method. 

As discussed in Section 16.1.4, polymer-bound acetoacetates can be used as precursors for the solid-phase synthesis of enones [30]. For these Knoevenagel condensations, the crucial step is to initiate enolization of the CH acidic component. For the microtvave-assisted enolization procedure, however, piperidinium acetate was found to be the catalyst of choice, if temperatures were kept below 130 °C. A 21-member library, of polymer-bound enones was generated (Scheme 16.33) by using a multi-vessel rotor system for parallel microwave-assisted synthesis. Reaction... 

Microwave-Assisted Synthesis Involving Immobilized Catalysts... 

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