High Intensity Ultrasounds

Villamiel, M. and Jong, P. D. (2000b). Influence of high-intensity ultrasound and heat treatment in continuous flow on fat, proteins, and native enzymes of milk. /. Agric. Food Chem. 48, 472-478. 

No Catalyst. High-intensity ultrasound was employed to reinvestigate the aldol reaction in water without any catalyst.256 Within... 

In order to generate a high intensity ultrasound, an ultrasonic horn has been used (Fig. 1.14). The electric system is the same as that in a bath-type reactor. 

An ultrasonic horn has a small tip from which high intensity ultrasound is radiated. The acoustic intensity is defined as the energy passing through a unit area normal to the direction of sound propagation per unit time. Its units are watts per square meter (W/m2). It is related to the acoustic pressure amplitude (P) as follows for a plane traveling wave [1]. 

Cravotto G, Beggiato M, Penoni A, Palmisano G, Tollari S, Leveque J-M, Bonrath W (2005) High-intensity ultrasound and microwave alone or combined, promote Pd/C-catalyzed aryl-aryl couplings. Tetrahedr Lett 46 2267-2271... 

Fig. 4.3 Electrode-apart-transducer configuration (a) small volume cell (b) preparative cell for bulk electrolysis in the presence of high intensity ultrasound. (Acknowledge [46]. Reproduced by permission of The Royal Society of Chemistry)...

Zhang H, Coury LA Jr (1993) Effects of high-intensity ultrasound on glassy carbon electrodes. Anal Chem 65 1552-1558... 

Suslick KS, Hyeon T, Fang M (1996) Nanostructured materials generated by high-intensity ultrasound sonochemical synthesis and catalytic studies. Chem Mater 8 2172-2179... 

Self-assembled nanorods of vanadium oxide bundles were synthesized by treating bulk V2O5 with high intensity ultrasound [34]. By prolonging the duration of ultrasound irradiation, uniform, well defined shapes and surface structures and smaller size of nanorod vanadium oxide bundles were obtained. Three steps which occur in sequence have been proposed for the self-assembly of nanorods into bundles (1) Formation of V2O5 nuclei due to the ultrasound induced dissolution and a further oriented attachment causes the formation of nanorods (2) Side-by-side attachment of individual nanorods to assemble into nanorods (3) Instability of the self-assembled V2O5 nanorod bundles lead to the formation of V2O5 primary nanoparticles. It is also believed that such nanorods are more active for n-butane oxidation. 

O.V. Abramov, High-Intensity Ultrasound Theory and Industrial Applications, Gordon and Breach, London, 1998. 

Sonication, the application of high-intensity ultrasound at frequencies beyond the range of human hearing (16 kHz), of a monomer results in radical polymerization. Initiation results from the effects of cavitation—the formation and collapse of cavities in the liquid. The collapse (implosion) of the cavities generates very high local temperatures and pressures. This results in the formation of excited states that leads to bond breakage and the formation of... 

In 2004, the Reformatsky reactions of imine, a-bromoester, zinc dust, and a catalytic amount of iodine in dioxane under high intensity ultrasound (HIU) irradiation have been reported to afford (3-lactam and the corresponding (3-aminoester [178]. The reactions were performed in short reaction times and high yields of both products or a mixture of the two products were obtained, depending on the starting imine and on the a-bromoester (Scheme 79). 

M.G. Sirotyuk, Experimental investigation of ultrasonic cavitation, in L.D. Rozenberg (Ed.), Physics and Technology of High-Intensity Ultrasound, Vol. 2, High-Intensity Ultrasonic Fields, Nauka, Moscow, 1968. 

Hydrostannylation This reaction with a tin hydride normally requires an initiator, usually AIBN but also B(C2H5)3 (14, 314). It can also be initiated with high intensity ultrasound, and such reactions show large rate acceleration (100-600 times) and take place even at temperatures of -50°. Sonication is also effective for radical reductions and cyclizations (last example). 

Li, Z.X., Linhong, C.L., Jamil, K. 2006. Reduction of allergenic properties of shrimp (Penaeus Vannamei) allergens by high intensity ultrasound. European Food Research and Technology 223(5) 639-644. 

A recently developed small-volume sono-voltammetric cell [69] in which the glassy carbon electrode is exposed to high intensity ultrasound was used in order to permit reliable simultaneous voltammetric determinations... 

Li, H., Pordesimo, L., and Weiss, J. 2004. High intensity ultrasound-assisted extraction of oil from soybeans. Food Research International, 37 731-738. 

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