The effect of ultrasound on organic synthesis and processing from laboratory to large scale test
The research programme involved the exploitation of ultrasound with a view to applications within commercial and processing industries. This was accomplished by employing dosimetry and calorimetry to study the efficiency of several sonochemical reactors. The effect of factors such as reaction vessel geometry and volume was investigated and the general trends obtained for all three dosimeters were comparable. The effects of various parameters e.g. power, solvent, volume etc etc on the sonochemical 0-allcylation of 2,6-dimethylphenol was examined. Decreases in temperature and volume, and increases in concentration and power, led to increases in the sonochemical effect. A study of the allcylation products from a reaction between 5-hydroxychromone-2-carboxylic acid ethyl ester with less reactive alkyl halides such as 1- and 2-bromobutane resulted in comparisons with phase transfer catalysis and conventional thermal methods. An investigation of the dehydrogenation of tetrahydronaphthalene under the influence of sonication was also attempted. Dehydrogenation was enhanced by sonication with sonochemical dehydrogenation occurring 20-40°C below the corresponding thermal reaction. Sonication as a processing aid was studied using examples taken from the food industry. The applications of particle size reduction, emulsification and crystallisation of various foodstuffs such as rice, sugar and cocoa grains were examined. The effect of sonication on the viscosity of gelled starch was also monitored with a view to achieving either a permanent or temporary reduction in viscosity.