2453-03-4Relevant articles and documents
Mechanochemical synthesis of poly(trimethylene carbonate)s: An example of rate acceleration
Park, Sora,Kim, Jeung Gon
, p. 963 - 970 (2019)
Mechanochemical polymerization is a rapidly growing area and a number of polymeric materials can now be obtained through green mechanochemical synthesis. In addition to the general merits of mechanochemistry, such as being solvent-free and resulting in high conversions, we herein explore rate acceleration under ball-milling conditions while the conventional solution-state synthesis suffer from low reactivity. The solvent-free mechanochemical polymerization of trimethylene carbonate using the organocatalysts 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) are examined herein. The polymerizations under ball-milling conditions exhibited significant rate enhancements compared to polymerizations in solution. A number of milling parameters were evaluated for the ball-milling polymerization. Temperature increases due to ball collisions and exothermic energy output did not affect the polymerization rate significantly and the initial mixing speed was important for chain-length control. Liquid-assisted grinding was applied for the synthesis of high molecular weight polymers, but it failed to protect the polymer chain from mechanical degradation.
Synthesis and thermolysis of a spiro-fused oxadiazoline - Evidence for sequential formation of carbene and oxirane intermediates, and for oxirane dimerization
Klys, Arkadiusz,Czardybon, Wojciech,Warkentin, John,Werstiuk, Nick Henry
, p. 1769 - 1773 (2004)
The spiro-fused oxadiazoline, 3,4-diaza-2,2-dimethyl-1,6,10-trioxaspiro[4. 5]dec-3-ene, when thermolysed in a sealed tube in benzene-d6 at 110 °C, afforded acetone and an apparent oxirane intermediate (2,2-dimethyl-1,4,8-trioxaspiro[2.5]octane) that could not be isolated. Attempts to isolate the oxirane gave a dimer (8,8,11,11-tetramethyl-1,5,7,10,12,16- hexaoxadispiro[5.2.5.2]hexadecane) as the major product. The oxirane is thermally stable at 110 °C but it is very sensitive to water, as indicated by its gradual disappearance after the tube was opened. The dimer of the oxirane is believed to form from a cation arising from the ring-opening of the oxirane when it reacts with moisture. This cation then reacts with the oxirane itself to regenerate water, which is effectively a catalyst for conversion of the oxirane to the dimer.
Experimental Evidence for the Stereoelectronically Controlled Hydrolysis of Orthocarbonates
Li, Shigui,Deslongchamps, Pierre
, p. 5641 - 5644 (1994)
The acid hydrolysis of cyclic and acyclic orthoesters 1-6 is reported.The results obtained are explained by taking into account the principle of stereoelectronic control.
Preparation and characterization of polyester- and poly(ester-carbonate)- paclitaxel conjugates
Sobczak, Marcin,Korzeniowska, Agnieszka,Go?, Piotr,Kolodziejski, Waclaw L.
, p. 3047 - 3051 (2011)
The polyester- and poly(ester-carbonate)-paclitaxel conjugates with low molecular weight were synthesized using dicyclohexylcarbodiimide (DCC) and dimethylaminopyridine (DMAP) as catalysts. Polymeric matrices were obtained by ring-opening polymerization of ε-caprolactone (CL), rac-lactide (rac-LA), l-lactide (LLA) and trimethylene carbonate (TMC). The macromolecular conjugates were characterized by using spectroscopic techniques, such as 1H, 13C NMR and FTIR. The degree of degradation of polyester- and poly(ester-carbonate)-paclitaxel conjugates was tested in vitro under different conditions. The preliminary results of drug release were discussed.
Supported Polyhedral Oligomeric Silsesquioxane-Based (POSS) Materials as Highly Active Organocatalysts for the Conversion of CO2
Calabrese, Carla,Liotta, Leonarda F.,Giacalone, Francesco,Gruttadauria, Michelangelo,Aprile, Carmela
, p. 560 - 567 (2019)
Very high turnover numbers (TON) and productivity values up to 7875 and 740 respectively have been obtained for the conversion of CO2 into cyclic carbonates by using hybrid materials based on imidazolium modified polyhedral oligomeric silsesquioxanes (POSS-Imi) grafted on amorphous silica (SiO2) and mesostructured SBA-15. The heterogeneous organocatalysts were easily prepared via a straightforward synthetic procedure allowing to generate high local concentration spots of imidazolium active sites surrounding the POSS core. This synthetic procedure is also a promising approach for the design of a wide library of hybrid functional materials. The materials do not possess other co-catalytic species with Lewis or Br?nsted acid functionalities which still represents a challenging aspect for the outcome of the process. The recyclability of the catalysts was successfully verified for four consecutive runs. The catalytic versatility was proved with a wide range of epoxides and with the most challenging oxetane on large scale (105–210 mmol) showing higher performances in comparison with other unmodified imidazolium-based catalytic systems. The new hybrids based on supported POSS nanostructures allowed the sustainable conversion of carbon dioxide under solvents- and metal-free reaction conditions with a full selectivity toward cyclic carbonates.
CYCLOADDITION OF OXETANE AND CARBON DIOXIDE CATALYZED BY TETRAPHENYLSTIBONIUM IODIDE
Baba, Akio,Kashiwagi, Hiroki,Matsuda, Haruo
, p. 1323 - 1324 (1985)
Trimethylene carbonate was readily obtained in the reaction of oxetane and carbon dioxide in the presence of tetraphenylstibonium iodide.
Synthesis of cyclic carbonates with carbon dioxide and cesium carbonate
Reithofer, Michael R.,Sum, Yin Ngai,Zhang, Yugen
, p. 2086 - 2090 (2013)
Cyclic carbonates are important compounds for the synthesis of biocompatible polymers and linear dialkyl carbonates, as well as solvents and electrolytes. We report here the synthesis of such compounds from easily accessible starting materials with carbon dioxide as a C1 source and caesium carbonate as the base. This new methodology is able to yield 5- and 6-membered cyclic carbonates very efficiently in a green manner.
Selective formation of trimethylene carbonate (TMC): Atmospheric pressure Carbon dioxide utilization
Buckley, Benjamin R.,Patel, Anish P.,Wijayantha, K.G. Upul
, p. 474 - 478 (2015)
Carbon dioxide utilisation (CDU) is currently gaining increased interest due to the abundance of CO2 and its possible application as a C1 building block. We herein report the first example of atmospheric pressure carbon dioxide incorporation into oxetane to selectively form trimethylene carbonate (TMC), which is a significant challenge as TMC is thermodynamically less favoured than its corresponding co-polymer.
Mechanistic studies of the copolymerization reaction of oxetane and carbon dioxide to provide aliphatic polycarbonates catalyzed by (salen)CrX complexes
Darensbourg, Donald J.,Moncada, Adriana I.,Choi, Wonsook,Reibenspies, Joseph H.
, p. 6523 - 6533 (2008)
Chromium salen derivatives in the presence of anionic initiators have been shown to be very effective catalytic systems for the selective coupling of oxetane and carbon dioxide to provide the corresponding polycarbonate with a minimal amount of ether linkages. Optimization of the chromium(III) system was achieved utilizing a salen ligand with tert-butyl groups in the 3,5-positions of the phenolate rings and a cyclohexylene backbone for the diimine along with an azide ion initiator. The mechanism for the coupling reaction of oxetane and carbon dioxide has been studied. Based on binding studies done by infrared spectroscopy, X-ray crystallography, kinetic data, end group analysis done by 1H NMR, and infrared spectroscopy, a mechanism of the copolymehzation reaction is proposed. The formation of the copolymer is shown to proceed in part by way of the intermediacy of trimethylene carbonate, which was observed as a minor product of the coupling reaction, and by the direct enchainment of oxetane and CO2. The parity of the determined free energies of activation for these two processes, namely 101.9 kJ·mol-1 for ring-opening polymerization of trimethylene carbonate and 107.6 kJ·mol-1 for copolymerization of oxetane and carbon dioxide supports this conclusion.
Ultrasound-assisted synthesis of a stable Co(II) coordination polymer as heterogeneous catalyst for CO2 transformation
Liu, Ce,Liu, Lin,Han, Zheng-Bo
, (2021)
A stable benzimidazole-containing Co(II) coordination polymer namely [Co(L)0.5(oba)]n (1) (H2oba = 4,4′-oxybis(benzoate), L = 1,6-bis(5,6-dimethylbenzimidazolyl) hexane) was successfully synthesized by ultrasonic technique under mild conditions. In especial, the effects of initial reagent concentration, irradiation time and ultrasonic power on the morphology and size of micron scale 1 were discussed in detail. Micron scale 1 appeared exceptional solvent and pH stabilities. Further, as a heterogeneous Lewis catalyst, 1 exhibited a highly activity and recyclability for CO2 transformation by cycloaddition with epoxide under room temperature.
