Kinetics of the condensation of urea with some aliphatic aldehydes |
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| Affiliation: | 1. Wheaton Franciscan Healthcare, Center for Neurological Disorders, 3237 South 16th Street, Milwaukee, WI 53215, United States;2. Wheaton Franciscan Healthcare, St. Joseph’s Hospital, Department of Neonatology, 5000 West Chambers, Milwaukee, WI 53211, United States;3. Perelman School of Medicine, University of Pennsylvania, Department of Neurology, 295 John Morgan Building, 3620 Hamilton Walk, Philadelphia, PA 19104-6055, United States;1. New Technologies - Research Centre, University of West Bohemia, Univerzitni 8, 306 14 Pilsen, Czech Republic;2. Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee, 1784 Sofia, Bulgaria;3. School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis, Malaysia;1. Electrical Engineering Department, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia;2. Department of Civil, Architectural and Environmental Engineering, University of Texas Austin, USA |
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| Abstract: | The rate and equilibrium constants of the condensation of urea with some aliphatic aldehydes to form alkylidenediureas have been measured spectrophotometrically in aqueous solutions at 24·2°. The rate is always expressed as: v = k[H2NCONH2][free RCHO]. Electron-releasing groups in aldehydes tend to decrease the rate of forward reaction with Taft's ρ* value of +3·5. The reaction is reversible and is subject to both acid and base catalysis. The Brönsted catalysis law, κA = GAKAα, is applicable to the acid catalysis, and the α values in the equation are 0·38 for propionaldehyde, 0·43 for n-butyraldehyde, and 0·45 for isobutyraldehyde. These results agree with the expectation from the suggested reaction mechanism involving the rate-determining attack of urea on free aldehyde molecule. |
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