Acoustic agitation of a carbon dioxide/water mixture in a 1 dm3 cylindrical, high-pressure reactor led to the simultaneous formation of carbon dioxide/water (C/W) and water/carbon dioxide (W/C) emulsions, with the dispersed phase occupying up to 10% of the volume. These emulsions were stable for several minutes. Inclusion of 1% of the non-ionic surfactant Tween 80 led to the generation of C/W emulsions which were stable for over 1 hour after ceasing sonication, in which all of the carbon dioxide present in the system comprised the dispersed phase. The mixing capacity of pulsed ultrasound was assessed by studying the mass transfer of benzaldehyde across the carbon dioxide/water interface, leading to determination of the system mixing time. A model for mass transfer with a fast chemical reaction, namely the hydrolysis of benzoyl chloride, was used to separate the mass transfer and kinetic effects, and to identify those reactions that would most significantly benefit from ultrasound-induced emulsification. For the first time, the Barbier synthesis was shown to occur in a carbon dioxide/water mixture as solvent, leading to moderate to high yields. Moreover, it was possible to recover the homoallylic alcohol product directly from the carbon dioxide phase in which it was preferentially partitioned.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:619418 |
| Date | January 2014 |
| Creators | Cenci, Steven Michael |
| Publisher | University of Birmingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://etheses.bham.ac.uk//id/eprint/5381/ |
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