Title: Spectroscopy of Hydrothermal Reactions. 5. Decarboxylation Kinetics of Malonic Acid and Monosodium Malonate
Abstract: The kinetics of decarboxylation of 1.07 m malonic acid and monosodium malonate at 120−230 °C and 275 bar were determined directly in a combined microflow reactor and short-pathlength IR spectroscopy cell. Malonic acid and monosodium malonate decomposed in a single step to CO2 and acetic acid and CO2 and the acetate ion, respectively. The kinetics for malonic acid were modeled as an equilibrium between malonic acid and the monoanion with parallel decarboxylation of both species. The Arrhenius parameters are Ea = 120 ± 2 kJ/mol and ln A (s-1) = 29.4 ± 0.1 for the malonate monoanion and Ea = 126 ± 2 kJ/mol and ln A (s-1) = 31.4 ± 0.1 for malonic acid in a 316 stainless steel flow reactor at 120−210 °C. Decarboxylation of the monoanion is slower than that of malonic acid. The rates of decarboxylation of malonic acid are slower above 140 °C in a Pt/Ir alloy flow reactor with diamond windows than in a 316 stainless steel flow reactor with sapphire windows.
Publication Year: 1996
Publication Date: 1996-01-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 42
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