Sonocatalysis

Sonochemistry can be roughly divided into categories based on the nature of the cavitation event homogeneous sonochemistry of hquids, heterogeneous sonochemistry of hquid—hquid or hquid—sohd systems, and sonocatalysis (which overlaps the first two) (12—15). In some cases, ultrasonic irradiation can increase reactivity by nearly a million-fold (16). Because cavitation can only occur in hquids, chemical reactions are not generaUy seen in the ultrasonic irradiation of sohds or sohd-gas systems. 

Fig. 13. Relative rates and trans/cis ratios of the sonocatalysis of 1-pentcne isomerization by metal carbonyls. [Plotted from data in Ref. 183.]...

Recently, we have demonstrated another sort of homogeneous sonocatalysis in the sonochemical oxidation of alkenes by O2. Upon sonication of alkenes under O2 in the presence of Mo(C0) , 1-enols and epoxides are formed in one to one ratios. Radical trapping and kinetic studies suggest a mechanism involving initial allylic C-H bond cleavage (caused by the cavitational collapse), and subsequent well-known autoxidation and epoxidation steps. The following scheme is consistent with our observations. In the case of alkene isomerization, it is the catalyst which is being sonochemical activated. In the case of alkene oxidation, however, it is the substrate which is activated. 

Sommelet process org chem The preparation of thiophene aldehydes by treatment of thiophene with hexamethylenetetramine.. so-mal ya, pra-s3s ) Sonnenschein s reagent analychem A solution of phosphomolybdicadd that forms a yellow precipitate with alkaloid sulfates. z6n-3n,shTnz r5,a-j3nt) sonocatalysis chem 1. Initiation of a catalytic reaction by irradiation with sound or ultrasound. 2. Use of sound to impart catalytic activity to a chemical compound. san-3-k3 tal-3-s3s)... 

S. Brochette-Lemoine, D. Joannard, G. Descotes, A. Bouchu, and Y. Queneau, Sonocatalysis of the TEMPO-mediated oxidation of glucosides, J. Mol. Catal. A Chem., 150 (1999) 31-36. 

Martin-Aranda. RM Ortega-Cantero. H Roja.s-Cervanies. ML. Vicente-Rodriguez, MA Baflares-Munoz. MA. Sonocatalysis and basic clays.. Michael. ddition Between imidazole and ethyl acrylate. Catalysis Letters. 2002 84. 201-204. 

Suslick KS, Schubert PF, Goodale JW. (1981). Sonochemistry and sonocatalysis of iron carbonyls./owma/ of the American Chemical Society 103 7342-7344. 

One of the most important aspects inherent in sonochemistry concerns synthesis and treatment of organic and inorganic materials. Effects of ultrasound on chemical transformations were studied in three directions sonochemistry in homogeneous liquid system, sonochemistry in heterogeneous liquid-liquid or liquid-solid several times as well as sonocatalysis. Thus, the cavitation concentrates sound energy to affect the synthesis from soluble precursors. Chemical reactions are usually not observed in sonicated solid-solid and solid or gas systems. 

Pizzuti, L., Piovesan, L. A., Elores, A. E. C., Quina, E. H. and Pereira, C. M. P. 2009. Environmentally friendly sonocatalysis promoted preparation of 1-thiocarbamoy 1-3,5-diaryl-4,5-dihydro-17/-pyrazoles. Ultrason. Sonochem. 16 728—731. 

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