On the interaction between supercritical CO2 and epoxides combining infrared absorption spectroscopy and quantum chemistry calculations

Abstract

The nature and strength of the interactions occurring between epoxides and CO(2) have been investigated by combining infrared spectroscopy with quantum chemistry calculations. A series of infrared absorption experiments on four model epoxide molecules highly diluted in supercritical CO(2) have been performed at constant temperature T = 40 °C for various CO(2) pressures varying from 1 to 30 MPa. Then, we carried out a theoretical analysis based on quantum chemistry calculations using Density Functional Theory (B3PW91 and CAM-B3LYP) and ab initio (MP2) computational methods. A very good agreement between experimental and calculated vibrational frequency shifts of the epoxide ring vibrations group was obtained using the CAM-B3LYP functional, hence validating the calculated optimized geometries of the epoxide-CO(2) complexes. Whatever the epoxide considered, CO(2) is found to be on average above the oxygen atom of the epoxy ring and interacts with the carbon atom of CO(2) through a Lewis acid-Lewis base type of interaction. The substituents on the epoxide ring are found to influence the stability of the epoxide-CO(2) complexes mainly because of the partial charge on the oxygen atom that is sensitive to the nature of the substituent.

Theoretical Studies on the Fixation of CO2 with Propylene Oxide Catalyzed by Squaramide/TEAB

“…Firstly, in the absence of any catalyst, the calculated potential surface (PES) profile for the cycloaddition between propylene oxide ( PO ) and CO 2 is shown in Figure . As the propylene oxide and CO 2 get close to each other, a bimolecular intermediate, denoted as Int , was formed where PO plays the role of the Lewis base and CO 2 acts as the Lewis acid . In Int , the O⋅⋅⋅H1 and O⋅⋅⋅H2 distances are 3.00 Å and 3.07 Å, respectively.…”

Novel green fatty acid-based bis-cyclic carbonates for the synthesis of isocyanate-free poly(hydroxyurethane amide)s

“…Various reaction conditions have been used for the carbonation of epoxide. After in-situ FTIR investigations to monitor the kinetics of the carbonation reaction, [22][23][24] (See ESI) the following procedure has been chosen. After 24 hours, full conversion was attained for all fatty acid-based bis epoxides using the following reaction conditions: 80°C / 50 Bar for UndPdE-bisEpoxide, UndPMedA-bisEpoxide bis-epoxide and UndPipdA-b5CC clearly demonstrates the formation of the cyclic carbonate.…”

Surface‐enhanced Raman scattering properties of Lewis acid–base complexes ofp‐hydroxybenzoic andp‐mercaptobenzoic acids with CO2in the presence of silver

“…Both complexes are supposed to be mostly stabilized by the interaction between the carboxylic group oxygen atom and the electron-deficient carbon atom of CO 2 . This assumption is noticed by the structural evidence of a C = OÁÁÁC bond formed in both complexes, which exhibit a characteristic geometry of LA-LB complexation, [16][17][18][19][20][21][22][23][24][25][26] similar to that occurring in other carbonyl compounds with CO 2 . [17,19,22] The interaction with Ag is represented by substituting the hydrogen atom covalently bonded to the X atom (as indicated in Fig.…”

“…Hence, by comparing SERS spectra, obtained under normal and scCO 2 conditions, possible effects from the intermolecular interactions could be further understood. In the case of PHBA and PMBA, the presence of an available carboxylic group would be sufficient to interact with a CO 2 molecule, giving rise to the so‐called Lewis acid–base (LA–LB) interactions . In this sense, we propose that SERS/scCO 2 spectroscopy can be also employed to rationalize LA–LB complexations involving noble metals.…”

“…In the case of PHBA and PMBA, the presence of an available carboxylic group would be sufficient to interact with a CO 2 molecule, giving rise to the so-called Lewis acid-base (LA-LB) interactions. [16][17][18][19][20][21][22][23][24][25] In this sense, we propose that SERS/scCO 2 spectroscopy can be also employed to rationalize LA-LB complexations involving noble metals.…”