Ultrasound experiments

Figure 1 Time-dependent composition data is shown for the hydrogenation of aqueous 3-buten-2-ol for both (a) ultrasound irradiated and (b) magnetically stirred systems. The symbols correspond to experimental measurements (3-buten-2-ol 3BEN20L-solid circles 3-buten-2-one 3BEN20NE-open hourglass 2-butanone 2BONE-open triangles 2-butanol 2BOL-crossed squares). The lines in the ultrasound experiment simply connect the data points, whereas for the stirred experiment the lines correspond to a modeled fit (see text).

Figure 1 shows the effect of progressively increased conformational motion as the applied ultrasonic intensity is increased. It also shows the NMR spectrum of the sample when heated to 44 °C. The sample had to be heated electrically to over 100 °C before an equivalent H CH3 resonance coalescence occurred. After the ultrasound experiment the final temperature was ca. 30 °C. 

Figuro 4 The ee - conversion dependencies obtained in the presence of Ptoi varying the character of excess alkaloid ((CN) . or (CD)ex)- A - experiment in the presence of (CN), A - experiment in the presence of (CD) without treatment with ultrasound, ,<> - experiment in the presence of (CD) after treatment with ultrasound. The concentration of excess alkaloids is 6.8 x 10 M.

In attempts to prepare homoallyl alcohol in an environmental friendly process, Andrews and co-workers reported its synthesis using a solvent-free method mediated by tin under ultrasound. Experiments showed that the alcohols were produced in excellent yields with aldehydes but that no products were produced using ketones. However, the existence of toxic allyltin compounds in the final products prevented the method from being applied downstream in fine chemical applications. On the other hand, according to Wang et carbonyl allylation reactions mediated by SnCl2 in aqueous solution without a Lewis acid under ultrasonic irradiation were successfully carried out. 

S. A. R. K. Deshmukh, J. A. Laverman, A. H. G. Cents, M. Van Sint Annaland and J. A. M. Kuipers, Development of a membrane assisted fluidized bed reactor. 1. Gas phase back-mixing and bubble-to-emulsion phase mass transfer using tracer injection and ultrasound experiments, Ind. Eng. Chem. Res., 2005, 44, 5955 5965. 

I. Gas phase back-mixing and bubble-to-emulsion phase mass transfer using tracer injection and ultrasound experiments. Ind. 

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