Studies of the Isomerization of Unsaturated Carboxylic Acids. II. The Thermal Rearrangement of Citraconic Acid to Itaconic Acid in Aqueous Solutions

Abstract

The thermal reaction of citraconic acid (2) in water gives a mixture of products similar to that obtained from itaconic acid (1) in water. After 22 h at 170 °C, the equilibrium composition about 74%, 18%, and 8% 1, 2, and mesaconic acid respectively. At the optimum conditions (170 °C for 3 h), the yield of 1 is 65%. The mechanism of the reaction is discussed.

Efficient bio-production of citramalate using an engineered Escherichia coli strain

“…However, the citraconate must be synthesized by the thermal decomposition of citric acid [ 10, 25, 26 ], which in turn needs to be produced by fermentation [ 27 ], increasing the cost. Similarly, itaconate is produced either by direct fermentation [ 28 ], or from citric acid as above [ 25, 26 ]. Furthermore, the growth and preparation of the harvested cells requires multiple unit operations, adding to process complexity and cost.…”

Spectroscopy of Hydrothermal Solutions 18: pH-Dependent Kinetics of Itaconic Acid Reactions in Real Time

“…Detailed studies of the pH dependence of decarboxylation of one such acid, malonic acid, have been reported recently . Itaconic acid (I) is another dicarboxylic acid that has attracted attention in the hydrothermal regime. − It was first known as a byproduct of the pyrolysis of citric acid . It is produced industrially by fermentation of Aspergillus terreus and has been of interest in polymer industry as a monomer and a copolymer component in part because of its availability from a renewable nonpetroleum resource , and in part because it enhances the properties of polymer coatings…”

“…The hydrothermal chemistry of itaconic acid is potentially rather complex as a result of the presence of three functional groups, each of which contributes to the reaction pathways. Decarboxylation, isomerization (e.g., formation of citraconic acid (II) and mesaconic acid (III)), and hydration are known to occur at high temperature. ,, In addition, protonation occurs in highly acidic solution, and polymerization can be initiated in aqueous solution …”

“…The complexity of the network makes such determinations into a particularly thorny problem. Nevertheless, it appeared to be possible to establish the kinetics of at least the decarboxylation of itaconic acid because itaconic acid has been indicated to be the least stable of all of the carboxylate species in the reaction network toward decarboxylation and isomerization of the other isomers to itaconic acid preceded their decarboxylation. ,, The kinetic behavior of itaconic acid was determined in real time at hydrothermal conditions as a function of the pH by the use of an FTIR spectroscopy flow reactor. − Density functional theory calculations were also conducted to provide additional insight into the experimental data and mechanism.…”

Study of the sequential conversion of citric to itaconic to methacrylic acid in near-critical and supercritical water

“…Acetoacetic acid readily decomposes into carbon dioxide and acetone at low temperatures (Loudon, 1988). Moreover, equilibration of the propenedicarboxylic acids is known to be fast in water solutions at elevated temperatures (Linstead and Mann, 1931;Sakai, 1976); thus itaconic acid may rearrange to citraconic and mesaconic acids (see Figure 1) more rapidly than it decarboxylates to form methacrylic acid.…”