Thermodynamic and Kinetic Study of Diels–Alder Reaction between Furfuryl Alcohol and N-Hydroxymaleimides—An Assessment for Materials Application

Abstract

The study of Diels–Alder reactions in materials science is of increasing interest. The main reason for that is the potential thermoreversibility of the reaction. Aiming to predict the behavior of a material modified with maleimido and furyl moieties, 1H NMR and UV-Vis solution studies of the Diels–Alder reaction between furfuryl alcohol and two N-hydroxymaleimides are explored in the present study. Rate constants, activation energy, entropy, and enthalpy of formation were determined from each technique for both reacting systems. Endo and exo isomers were distinguished in 1H NMR, and the transition from a kinetic, controlled Diels–Alder reaction to a thermodynamic one could be observed in the temperature range studied. A discussion on the effect of that on the application in a material was performed. The approach selected considers a simplified equilibrium of the Diels–Alder reaction as the kinetic model, allowing materials scientists to evaluate the suitability of using the reacting molecules for the creation of thermoresponsive materials. The proposed approach determines the kinetic constants without the direct influence of the equilibrium constant value, thereby allowing a more objective data analysis. The effects of the selection of kinetic model, analytical method, and data treatment are discussed.

Simple Synthesis of Complex Amines from the Diels–Alder Adducts of (–)-Cytisine

“…It should be noted that the calculated reaction energies for 2a + 3a = 4k + 5k are comparable to the experimentally determined enthalpy values for the Diels-Alder reaction of N-hydroxy-and N-hydroxyethylmaleimide with furfuryl alcohol. 12 Similarly, our calculated activation energy values are comparable to the experimentally found ones for the Diels-Alder reaction between furan with N-phenylmaleimide 13 as well as DFT calculated values for eight different Diels-Alder reactions. 14 In conclusion, N-benzylcytisine (2c) reacts with Nmethyl-and N-benzylmaleimides (3a and 3e) in refluxing toluene to give two endo-isomeric Diels-Alder adducts 4 with syn-and 5 with anti-orientation of the imide group with respect to the methylene group of the 3,7-diazabicyclo-[3.3.1]nonane fragment.…”

Designing Hydrogels for 3D Cell Culture Using Dynamic Covalent Crosslinking

“…[ 31 ] Kinetic studies have determined that the retro Diels–Alder reaction is more favorable at higher temperature. [ 77 ] Moreover, the maleimide group is susceptible to hydrolysis, which then inhibits the forward reaction. [ 77,92,93 ] As a result, the stability of Diels–Alder crosslinked hydrogels is limited to 1–3 weeks.…”

“…[ 77 ] Moreover, the maleimide group is susceptible to hydrolysis, which then inhibits the forward reaction. [ 77,92,93 ] As a result, the stability of Diels–Alder crosslinked hydrogels is limited to 1–3 weeks. [ 31,93 ]…”

Production of a PET//LDPE Laminate Using a Reversibly Crosslinking Packaging Adhesive and Recycling in a Small-Scale Technical Plant

“…In the solvent, once an adduct is opened, the functional groups can be surrounded by a solvate shell and thus washed away from the interlayer of the composite, becoming less likely due to dilution. It is also conceivable that the kinetics of the retro-Diels-Alder reaction could be affected since it is known that the solvent has an influence on the kinetics of the Diels-Alder reaction [17,[31][32][33][34][35]. However, Widstrom et al [36] performed studies on the kinetics of the retro-Diels-Alder reaction between a maleimide and furan in different solvents and could not demonstrate any influence.…”