Five-membered Cyclic Carbonates Research Articles

An improved boron-catalyzed cycloaddition of CO2 to epoxides for the production of five-membered cyclic carbonates under atmospheric versus high-pressure conditions

A series of novel boron-based compounds (boronate esters) (1–8) were designed and successfully synthesized by introducing 3-(bromomethyl)phenylboronic acid into the various cis-diols using a Dean-Stark trap to remove the water formed during the esterification reactions. The synthesized boron-based compounds were characterized by 1H, 13C, and 11B NMR, FT-IR, UV–Vis, LC-MS/MS, elemental analysis, TGA-DTA, and melting point measurement techniques. Additionally, the Lewis acidity of the synthesized boronate esters was investigated by the conventional Gutmann-Beckett test. After the boronate esters were characterized in detail by various spectroscopic techniques, these compounds have been used as organocatalysts for the highly efficient conversion of greenhouse gas CO2 to cyclic carbonates under atmospheric versus high-pressure conditions without any solvents. The best conversion was performed in the presence of an organoboron catalyst (3) and DMAP as cocatalyst, with a 90.0 % yield and 97.7 % selectivities under high reactor pressure and with a 45.2% yield and 97.4% selectivities under atmospheric conditions. In addition, after it was determined that the target organoboron catalysts showed high catalytic activity, the effects of epoxide, base, temperature, CO2 pressure, Lewis acidity, reaction time, and amount of catalyst and base on the catalytic conversion were investigated for these catalysts.

Preparation of Non-Isocyanate Polyurethanes from Mixed Cyclic-Carbonated Compounds: Soybean Oil and CO2-Based Poly(ether carbonate).

This study presents the synthesis and characterization of non-isocyanate polyurethanes (NIPU) derived from the copolymerization of cyclic-carbonated soybean oil (CSBO) and cyclic carbonate (CC)-terminated poly(ether carbonate) (RCC). Using a double-metal cyanide catalyst, poly(ether carbonate) polyol was first synthesized through the copolymerization of carbon dioxide and propylene oxide. The terminal hydroxyl group was then subjected to a substitution reaction with a five-membered CC group using glycerol-1,2-carbonate and oxalyl chloride, yielding RCC. Attempts to prepare NIPU solely using RCC and diamine were unsuccessful, possibly due to the low CC functionality and the aminolysis of RCC's linear carbonate repeating units. However, when combined with CSBO, solid NIPUs were successfully obtained, exhibiting good thermal stability along with enhanced mechanical properties compared to conventional CSBO-based NIPU formulations. Overall, this study underscores the potential of leveraging renewable resources and carbon capture technologies to develop sustainable NIPUs with tailored properties, thereby expanding their range of applications.

On Sustainability Aspects of the Synthesis of Five-Membered Cyclic Carbonates

On Sustainability Aspects of the Synthesis of Five-Membered Cyclic Carbonates

Photoredox-catalyzed oxytrifluoromethylation of alkenes toward CF3-containing five-membered cyclic carbonates

A visible-light-induced oxytrifluoromethylation reaction of carbamate-containing alkenes has been reported for the synthesis of diverse cyclic carbonates and vicinal diols bearing trifluoroethyl substituted quaternary centers.

Exploring enantiopure zinc-scorpionates as catalysts for the preparation of polylactides, cyclic carbonates, and polycarbonates.

New and simple ligand design strategies for the preparation of versatile metal-based catalysts capable of operating under greener and eco-friendly conditions in several industrially attractive processes are in high demand for society development. We present the first nucleophilic addition of an organolithium to ketenimines which incorporates a stereogenic centre in an N-donor atom to prepare new enantiopure NNN-donor scorpionates. We have also verified its potential utility as a valuable scaffold for chirality induction through the preparation of inexpensive, non-toxic and asymmetric zinc complexes. The pro-ligands and the corresponding zinc-based complexes have been characterized by X-ray diffraction studies. DFT studies were carried out to rationalize the different complexation abilities of these pro-ligands. These complexes have proved to act as highly efficient catalysts for a variety of sustainable bioresourced processes that are industrially attractive, with a wide substrate scope. Thus, complex 7 behaves as a highly efficient initiator for the well-behaved living ring-opening polymerization (ROP) of rac-lactide under very mild conditions. The PLA materials produced exhibited enhanced levels of isoselectivity, comparable to the highest value reported so far for zinc-based catalysts (Pi = 0.88). In addition, the combination of 7 with onium halide salts functioned as a very active and selective catalyst for CO2 fixation into five-membered cyclic carbonates through the cycloaddition of CO2 into epoxides under very mild and solvent-free conditions, reaching very good to excellent conversions (TOF = 227 h-1). Furthermore, this bicomponent system exhibits a broad substrate scope and functional group tolerance, including mono- and di-substituted epoxides, as well as the very challenging bio-renewable tri-substituted terpene-derived cis/trans-limonene oxide, whose reaction proceeds with high stereoselectivity. Finally, complex 7 also achieved high activity and selectivity as a one-component initiator for the synthesis of poly(cyclohexene carbonate)s via ring-opening copolymerization (ROCOP) of cyclohexene oxide and CO2 under very soft conditions, affording materials with narrow dispersity values.

Non-isocyanate polyurethanes synthesized from terpenes using thiourea organocatalysis and thiol-ene-chemistry

The depletion of fossil resources as well as environmental concerns contribute to an increasing focus on finding more sustainable approaches for the synthesis of polymeric materials. In this work, a synthesis route towards non-isocyanate polyurethanes (NIPUs) using renewable starting materials is presented. Based on the terpenes limonene and carvone as renewable resources, five-membered cyclic carbonates are synthesized and ring-opened with allylamine, using thiourea compounds as benign and efficient organocatalysts. Thus, five renewable AA monomers are obtained, bearing one or two urethane units. Taking advantage of the terminal double bonds of these AA monomers, step-growth thiol-ene polymerization is performed using different dithiols, to yield NIPUs with molecular weights of above 10 kDa under mild conditions. Variation of the dithiol and amine leads to polymers with different properties, with Mn of up to 31 kDa and Tg’s ranging from 1 to 29 °C.

Optimization and kinetics modeling of CO2 fixation into cyclic carbonates using urea-functionalized ionic organic polymers under mild conditions

Ionic organic polymeric materials are one of the most promising catalysts for the conversion of carbon dioxide (CO2) to five-membered cyclic carbonates (5CCs). Herein, a series of urea functionalized ionic organic polymer materials UIPs (UIP-1, UIP-2 and UIP-3) have been prepared by condensation and Menshutkin reaction of three components in one-pot by solvothermal method. After characterization by FT-IR, SEM, 13C CP MAS NMR, TGA, N2 adsorption and XPS spectroscopy, the UIPs were alternated as competitive catalysts for the CO2 cycloaddition reaction with epoxides without metal and co-catalyst under solvent-free conditions. In particular, UIP-2, derived from 1,3,5-tribromomethyl benzene, 4-amino pyridine and 4,4′-diphenylmethane diisocyanate, demonstrated excellent catalytic activity in the CO2 cycloaddition reaction with a high cyclic carbonate yield of 92.6 % under mild conditions: epichlorohydrin (ECH) (10 mmol), UIP-2 (0.10 mmol), reaction at 70 °C for 16 h with 1 bar of CO2, and the activated energy was calculated to be 48.5 kJ/mol. Furthermore, a possible catalytic mechanism was proposed by experiments and density functional theory (DFT) calculations.

Design and synthesis of ZnGlu MOF/SBA-16 nanocomposite, and its performance as an environmentally friendly nanocomposite for solvent-free chemical fixation of CO2 to epoxides for high-yield synthesis of cyclic carbonates

In this study, ZnGlu MOF has been immobilized into hexagonal mesoporous silica SBA-16 to fabricate ZnGlu MOF/SBA-16 hybrid material. The prepared hybrid material was introduced as a sustainable green nanocomposite for CO2 epoxidation to cyclic carbonates under solvent-free conditions at low pressure of CO2 (5 bar). The structure of the obtained nanocomposites is authenticated using various analytical techniques like FT-IR, XRD, SAXRD, CO2-TPD, NH3-TPD, BET, TEM, FE-SEM, EDX, EDX-mapping, and ICP-OES. For making a greener process, ZnGlu MOF/SBA-16 nanocomposite showed remarkable catalytic activity for converting CO2 with diverse epoxides toward five-membered cyclic carbonates prepared without using any toxic metals and reagents. The presence of the mesoporous silica SBA-16 has improved reactants diffusion and molecular accessibility for suitable interactions in Lewis acid centers, which led to MOFs outperforming in the efficient chemical fixation of CO2. Also, the essential role of free amino groups in ZnGlu MOF was shown as base sites and H-bonding groups when suggesting a possible reaction mechanism. This efficient, and convenient catalytic system can be separated by filtration, and its original activity was maintained for five successive cycles under the same reaction conditions. The above nanocomposite, with great potential, can be used to catalyze different chemical reactions for industrial purposes.

Efficient cycloaddition of carbon dioxide with epoxide to produce five-membered cyclic carbonates by amine-functionalized silicoaluminophosphates molecular sieves

The synthesis of functionalized microporous materials as very effective catalysts is a significant and rapidly increasing research topic with the goal for providing more efficient energy alternatives and contributing to the reduction of atmospheric CO2 levels. Carbon dioxide is a greenhouse gas that traps heat in the atmosphere, contributing to global warming and climate change. SAPO-5 and SAPO-34 molecular sieves were post-synthetically –NH2 functionalized, and the existence of –NH2 functionalities in the SAPO structure wall was demonstrated by FT-IR, CHN analysis. Powder XRD confirmed the crystalline structures of the modified SAPO-34 materials with amine functionalities. FE-SEM examined the morphology of the materials. The functionalized silicoaluminophosphate materials were investigated in the cyclo-addition of CO2 to epoxide (cyclohexene oxide and styrene oxide), where the catalytic performance of post-synthetically functionalized materials as catalyst were found to be superior. The amine group of the silicoaluminophosphates materials were essential for the activation of CO2. For treated SAPO-34, reactant conversion in cyclohexene oxide and styrene oxide was reported to be 94% and 93%, respectively. Because of the high recyclability of these materials, the catalysts are found to be both cost-effective and environmentally benign.

Synthesis and characterization of original fluorinated bis-cyclic carbonates and xanthates from a fluorinated epoxide

The development of efficient methods for the cycloaddition of CX2 (carbon dioxide (X=O) or carbon disulfide (X=S)) with fluorinated epoxides to produce five-membered cyclic carbonates (CCs) or cyclic xanthates (XAs) is a very attractive topic. In this work, the cycloaddition of CX2 with hexafluoropropene oxide (HFPO) was performed in the presence of a lithium bromide (LiBr) catalyst and optimized in terms of temperature, solvent, pressure, and reaction time. Then, the optimized conditions were tried in the cycloaddition of CX2 with 2-(trifluoromethyl)oxirane (TFEO) for reproducibility, leading to the corresponding products in high yields. Finally, two original fluorinated five-membered bis-CCs and bis-XAs were synthesized in high yields (85 and 87%) by reacting CX2 with 1,4-bis(2 ′ ,3 ′ -epoxypropyl) perfluorobutane (BEPFB). All of the resulting compounds were characterized by FTIR, 1H, 19F, and 13C NMR spectroscopy.

Nickel(II) Complexes of Tripodal Ligands as Catalysts for Fixation of Atmospheric CO2 as Organic Carbonates.

The fixation of atmospheric CO2 into value-added products is a promising methodology. A series of novel nickel(II) complexes of the type [Ni(L)(CH3 CN)2 ](BPh4 )2 1-5, where L=N,N-bis(2-pyridylmethyl)-N', N'-dimethylpropane-1,3-diamine (L1), N,N-dimethyl-N'-(2-(pyridin-2-yl)ethyl)-N'-(pyridin-2-ylmethyl) propane-1,3-diamine (L2), N,N-bis((4-methoxy-3,5-dimethylpyridin-2-ylmethyl)-N',N'-dimethylpropane-1,3-diamine (L3), N-(2-(dimethylamino) benzyl)-N',N'-dimethyl-N-(pyridin-2-ylmethyl) propane-1,3-diamine (L4) and N,N-bis(2-(dimethylamino)benzyl)-N', N'-dimethylpropane-1,3-diamine (L5) have been synthesized and characterized as the catalysts for the conversion of atmospheric CO2 into organic cyclic carbonates. The single-crystal X-ray structure of 2 was determined and exhibited distorted octahedral coordination geometry with cis-α configuration. The complexes have been used as a catalyst for converting CO2 and epoxides into five-membered cyclic carbonates under 1 atmospheric (atm) pressure at room temperature in the presence of Bu4 NBr. The catalyst containing electron-releasing -Me and -OMe groups afforded the maximum yield of cyclic carbonates, 34% (TON, 680) under 1 atm air. It was drastically enhanced to 89% (TON, 1780) under pure CO2 gas at 1 atm. It is the highest catalytic efficiency known for CO2 fixation using nickel-based catalysts at room temperature and 1 atm pressure. The electronic and steric factors of the ligands strongly influence the catalytic efficiency. Furthermore, all the catalysts can convert a wide range of epoxides (ten examples) into corresponding cyclic carbonate with excellent selectivity (>99%) under this mild condition.

Silver-Mediated Cascade Synthesis of Functionalized 1,4-Dihydro-2H-benzo-1,3-oxazin-2-ones from Carbon Dioxide.

A conceptually novel catalytic domino approach is presented for the synthesis of highly functional 1,4-dihydro-2H-1,3-benzoxazine-2-one derivatives. Key to the chemoselectivity is a proper design of the precursor to override thermodynamically favored parasitic cyclization processes and empower the formation of the desired product through Thorpe-Ingold effects. The synthetic diversity of these CO2 -based heterocycles is further demonstrated, and the isolation of a reaction intermediate supports an unusual ring-expansion sequence from an α-alkylidene, five-membered cyclic carbonate to a six-membered cyclic carbamate by N-induced isomerization.

Dicyano-functionalized indium framework as a heterogeneous catalyst for CO2 fixation in the absence of solvent and co-catalyst

MIL-68(In) modified with cyanide functional groups was synthesized and demonstrated appreciable catalytic results for the construction of five-membered cyclic carbonates via a cycloaddition reaction without any added solvent or co-catalyst.

Chemical recycling of CO2-based polycarbonates to sulfur-containing polymers

This work provides a “polymer A to polymer B” strategy for the upcycling of CO2-based poly(ether)carbonates to sulfur-containing polymers.

CO2 Deprotection-Mediated Switchable Polymerization for Precise Construction of Block Copolymers

A significant challenge in block copolymers (BCP) synthesis is to precisely control the block sequence and customize the composition and structure of target products from monomer mixtures. Herein, we reported a facile temperature-programmed switchable strategy based on deprotection chemistry of CO2, enabling precise construction of BCPs. The proposed pattern was achieved via temperature-triggered switchable terpolymerization of epoxides/five-membered cyclic carbonates/cyclic anhydrides based on the protection and deprotection chemistry of CO2. The chemoprotection of epoxides into cyclic carbonates and subsequent deprotection of cyclic carbonates into epoxides played a crucial role in the whole process. On the one hand, the low ring tension of five-membered cyclic carbonates resulted in vast temperature gaps between the copolymerization of epoxides/cyclic anhydrides and cyclic carbonates/cyclic anhydrides. Consequently, a facile control over the temperature-programmed parameter could direct the copolymerization cycles from epoxides/cyclic anhydrides (giving the first block at 110 °C) to cyclic carbonates/cyclic anhydrides (yielding the second block at 180 °C), thus ensuring precise fabrication of BCPs. Moreover, this protocol was significantly effective in extending the diversity of structures and properties of blocky polyesters by selecting distinct epoxide/cyclic carbonate combinations on demand.

Recent Advances in the Synthesis of Five-Membered Cyclic Carbonates and Carbamates from Allylic or Propargylic Substrates and CO2

The organic carbamates and carbonates are highly desirable compounds that have found a wide range of applications in drug design, medicinal chemistry, material science, and the polymer industry. The development of new catalytic carbonate and carbamate forming reactions, which employ carbon dioxide as a cheap, green, abundant, and easily available reagent, would thus represent an ideal substitution for existing methods. In this review, the advancements in the catalytic conversion of allylic and propargylic alcohols and amines to corresponding five-membered cyclic carbonates and carbamates are summarized. Both the metal- and the organocatalyzed methods are reviewed, as well as the proposed mechanisms and key intermediates of the illustrated carbonate and carbamate forming reactions.

Overview: Polycarbonates via Ring-Opening Polymerization, Differences between Six- and Five-Membered Cyclic Carbonates: Inspiration for Green Alternatives.

This review aims to cover the topic of polycarbonate synthesis via ring-opening polymerization (ROP) of cyclic carbonates. We report a wide variety of ROP-initiating systems along with their detailed mechanisms. We focus on the challenges of preparing the polymers; the precise control of the properties of the materials, including molecular weight; the compositions of the copolymers and their structural characteristics. There is no one approach that works for all scales in cyclic carbonates ROP. A green process to produce polycarbonates is a luring challenge in terms of CO2 utilization and the targeted domains for application. The main resolution seems to be the use of controlled incorporation of functional/reactive groups into polymer chains that can tailor the physicochemical and biological properties of the polymer matrices, producing what appears to be an unlimited field of applications. Glycerol carbonate (GC) is prepared from renewable glycerol and considered as a CO2 fixation agent resulting in GC compound. This family of five-membered cyclic carbonates has attracted the attention of researchers as potential monomers for the synthesis of polycarbonates (PCs). This cyclic carbonate group presents a strong alternative to Bisphenol A (BPA), which is used mainly as a monomer for the production of polycarbonate and a precursor of epoxy resins. As of December 2016, BPA is listed as a substance of very high concern (SVHC) under the REACH regulation. In 2006, Mouloungui et al. reported the synthesis and oligomerization of GCs. The importance of GCs goes beyond their carbonate ring and their physical properties (high boiling point, high flash point, low volatility, high electrical conductivity) because they also contain a hydroxyl group. The latter offers the possibility of producing oligo and/or polycarbonate compounds that have hydroxyl groups that can potentially lead to different reaction mechanisms and the production of new classes of polycarbonates with a wide range of applications.

Polymeric Materials Based on Carbon Dioxide: A Brief Review of Studies Carried Out at the Faculty of Chemistry, Warsaw University of Technology.

Carbon dioxide is an important raw material in many industrial technologies, but it is also one of the greenhouse gases that has to be effectively removed from the environment. This contribution provides a brief overview of carbon dioxide-based polymers developed in the laboratories of the Faculty of Chemistry at Warsaw University of Technology. We present some simple and versatile synthetic approaches that can be used to prepare a library of oligocarbonate diols, polycarbonates, poly(ester-carbonates), poly(ether-carbonates) and various types of polyurethanes, including the newly emerging family of environmentally friendly non-isocyanate polyurethanes. The main synthesis strategy involves the reaction of CO2 with oxiranes to form five-membered cyclic carbonates, which can be utilized as a source of carbonate bonds in polymeric materials obtained by the ester exchange reactions and/or step-growth polyaddition. We also show that cyclic carbonates are valuable starting materials in the synthesis of hyperbranched polymers and polymer networks. The properties of several CO2-based polymers are presented and their potential application as biomaterials, smart materials, and absorbers with a high CO2 capture capacity is discussed.

Structurally Diverse and Recyclable Isocyanate-Free Polyurethane Networks from CO2-Derived Cyclic Carbonates

Isocyanate-free chemistry and the introduction of dynamic bonds are a promising combination toward the development of more sustainable polyurethane (PU) networks. Here, we present the synthesis of reprocessable, isocyanate-free PU networks through atom-economical reactions for both monomers and polymers, valorizing CO2 as a building block. The monomers employed were five-membered cyclic carbonates prepared through an efficient (>99% conversion) reaction between CO2 and epoxides with high yield (up to 97% at a 100 gram scale), catalyzed by the moisture-tolerant and easily prepared DBU·I2 complex. The structural diversity of the monomers and the utilization of cystamine bearing the dynamic S–S motif realized PU networks with a finely tuned profile of thermal (Tg from −9 to 44 °C), mechanical (E from 0.2 to 1700 MPa), and viscoelastic properties (E′ from 0.03 to 5.5 MPa at 1 Hz). Facile recycling (100 °C, 20 min) of the networks was enabled thanks to the rapidly exchanging disulfide bonds and the modulated cross-link density. Moisture-induced plasticization of the networks was identified, and its effect on the properties of the networks was elucidated. The atom economy and energy-efficiency methodology, avoiding toxic reagents and preventing waste generation, make this approach an attractive and greener pathway to PU networks taking a step toward a circular plastic economy.

Complexities of Regioselective Ring-Opening vs Transcarbonylation-Driven Structural Metamorphosis during Organocatalytic Polymerizations of Five-Membered Cyclic Carbonate Glucose Monomers.

Rigorous investigations of the organobase-catalyzed ring-opening polymerizations (ROPs) of a series of five-membered cyclic carbonate monomers derived from glucose revealed that competing transcarbonylation reactions scrambled the regiochemistries of the polycarbonate backbones. Regioirregular poly(2,3-α-d-glucose carbonate) backbone connectivities were afforded by 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD)-catalyzed ROPs of three monomers having different cyclic acetal protecting groups through the 4- and 6-positions. Small molecule studies conducted upon isolated unimers and dimers indicated a preference for Cx–O2 vs Cx–O3 bond cleavage from tetrahedral intermediates along the pathways of addition–elimination mechanisms when the reactions were performed at room temperature. Furthermore, treatment of isolated 3-unimer or 2-unimer, having the carbonate linkage in the 3- or 2-position as obtained from either Cx–O2 or Cx–O3 bond cleavage, respectively, gave the same 74:26 (3-unimer:2-unimer) ratio, confirming the occurrence of transcarbonylation reactions with a preference for 3-unimer vs. 2-unimer formation in the presence of organobase catalyst at room temperature. In contrast, unimer preparation at −78 °C favored Cx–O3 bond cleavage to afford a majority of 2-unimer, presumably due to a lack of transcarbonylation side reactions. Computational studies supported the experimental findings, enhancing fundamental understanding of the regiochemistry resulting from the ring-opening and subsequent transcarbonylation reactions during ROP of glucose carbonates. These findings are expected to guide the development of advanced carbohydrate-derived polymer materials by an initial monomer design via side chain acetal protecting groups, with the ability to evolve the properties further through later-stage structural metamorphosis.