New Set of Multicomponent Crystals as Efficient Heterogeneous Catalysts for the Synthesis of Cyclic Carbonates

Abstract

Three new multicomponent crystals 1a–1c of Zn(II), Mn(II), and Co(II), respectively, were synthesized by the reaction of 2,6-bis(hydroxymethyl)pyridine, the respective metal salts, and sodium benzoate in a 1:1:2 ratio. One component of these multicomponent crystals 1a–1c is the dicationic 2,6-bis(hydroxymethyl)pyridine metal complex and the other component is the dianionic tetrabenzoate complex of the same metal. The complexes were fully characterized by single-crystal X-ray structure determination. The X-ray structure of these compounds 1a–1c reveals the formation of 1D supramolecular chain parallel to the crystallographic b axis via H-bonding interactions between the dicationic and dianionic parts of the respective compound. The Mn(II) ( 1b ) and Co(II) ( 1c ) complexes show antiferromagnetic coupling between the two associated metal centers via the H-bonding interaction pathway. All the three compounds 1a–1c were tested as heterogeneous catalytic systems for the successful conversion of epoxides to cyclic carbonates in solvent-free condition under approximately 10 bar of pressure of CO 2 and temperature ranging between 60 and 80 °C along with tetrabutyl ammonium bromide acting as a cocatalyst. All the three compounds 1a–1c were found to have turnover number more than 1000 for the respective epoxides except for the conversion of cyclohexene oxide to cyclohexene carbonate.

Mixing Effects on the Ternary Phase Diagram of Cocrystals and Gibbs Formation Energy Calculation

“…Cocrystallization has evolved as a strategy to develop novel solid forms of materials, particularly pharmaceuticals, 1−7 agrochemicals, 8,9 and other specialty chemicals, 10,11 to improve their physicochemical properties such as solubility, dissolution rate, hygroscopicity, stability, and mechanical properties. In this process, a multicomponent crystal, known as a cocrystal, is obtained by molecular mixing of two components, each of which are solid under ambient conditions.…”

“…Cocrystallization has evolved as a strategy to develop novel solid forms of materials, particularly pharmaceuticals, − agrochemicals, , and other specialty chemicals, , to improve their physicochemical properties such as solubility, dissolution rate, hygroscopicity, stability, and mechanical properties. In this process, a multicomponent crystal, known as a cocrystal, is obtained by molecular mixing of two components, each of which are solid under ambient conditions. , Understanding the thermodynamic properties of a cocrystal is essential to provide insights into its production, stability, and utilization. − While multiple methodologies have been reported for screening and manufacturing of cocrystals, the preparation of cocrystals by slurrying the components in a solvent is still the most widely followed method from the early development to the late phase of production. , Obtaining solubility data during development studies is routine.…”

3D Cyclophane for the Selective Conversion of Epoxide to Cyclic Carbonate

“…13 C­{1H} NMR (100 MHz,DMSO- d 6 , 27 °C) δ­(ppm) = 158.0 (C = O), 73.49 (O–CH), 70.44 (O–CH2), 18.94 (CH3) (Figures S32 and 33). Analytical data were in accordance with the literature. , …”

Green Synthesis of Novel Polyesterurethane Materials from Epoxides and Carbon Dioxide by New Set of One-Dimensional Coordination Polymer Catalyst

“…The catalytic cycloaddition reaction of the epoxides 2 and 3 to the corresponding cyclic carbonates 4 and 5 as shown in Scheme 2 was tried at 10 bar pressure of CO 2 and 80 o C in a 100 mL reactor with one-dimensional coordination polymers 1a and 1b as catalysts. In the previously reported studies of conversion of CO 2 to cyclic carbonates, it was observed that the reaction proceeds with the addition of the cocatalyst 37,39,48,49 tetrabutylammonium bromide along with the metal-based catalysts. In recent years, ionic liquid-based heterogeneous catalytic systems have been developed, which usually perform the catalytic reaction at higher temperature and pressure 50−52 but the reaction yield is found to be very high and with higher turnover numbers.…”