Studies On Hydrolysis And Condensation Reactions In Near-critical Water

Near-critical water can serve as a reactive medium for organic synthesis as a result of the changes that occur to its chemical and physical properties at elevated temperature. It has already shown its abilities to replace for many toxic organic solvents, and ability to catalyze reactions that traditionally require the addition of acid or base. The task of this work was to gain a better understanding of the hydrolysis and condensation reactions in near-critical water.The kinetics of non-catalyzed hydrolysis of phenylacetate in water at 150bar and temperature from 152℃ to 216℃ was investigated. From the results, we could see that no acid catalyst was needed for the hydrolysis reaction. With the increasing of temperature, the reaction rates increased sharply arid the selectivity of phenol went up from less than 50% to over 80%. The activation energy evaluated was 67.77 kJ/mol.Cinnamaldehyde was synthesized successfully through the reaction of phenylaldehyde with acetaldehyde in near-critical water, without any added catalyst or organic solvent. The phenylaldehyde conversion and the yield of cinnamaldehyde are influenced by the residence time, temperature, pressure and initial reactant volume. The optimal conditions are 260℃ , 160bar , 5hours, phenylaldehyde: acetaldehyde=l :3(mol), reactant:water=l: 15(volume).