Synthesis of Chiral Sulfur‐Containing Polymers: Asymmetric Copolymerization of <i>meso</i>‐Epoxides and Carbonyl Sulfide

Yue, Tian‐Jun; Ren, Wei‐Min; Chen, Li; Gu, Ge‐Ge; Liu, Ye; Lu, Xiao‐Bing

doi:10.1002/anie.201805200

Cited by 65 publications

(49 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These catalysts in some instances display superiority for catalyzing processes not accessible utilizing mononuclear catalysts. For example, dinuclear Co III complexes have exhibited excellent activity and high stereoselectivity in the copolymerization of meso ‐epoxides with COS or CO 2 , which is unachievable in a monometallic catalyzed manner [8b, 12d] . Hence, these observations led us to consider bimetallic catalyst systems for the terpolymerization processes.…”

Section: Resultsmentioning

confidence: 99%

“…These polythiocarbonates have good thermal stability, and their glass transition temperatures can be greater than 110 °C. Several of these copolymers are crystalline in nature and possess refractive indices up to 1.56 as measured by elliptical spectrometry [12d, 13] . Unfortunately, this increase in refractive index values led to a decrease in the Abbe number, an important parameter for evaluating the dispersion ability of refractive indices.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Randomly Distributed Sulfur Atoms in the Main Chains of CO₂‐Based Polycarbonates: Enhanced Optical Properties

et al. 2020

View full text Add to dashboard Cite

Polymeric materials possessing both high refractive indices and high Abbe numbers are much in demand for the development of advanced optical devices. However, the synthesis of such functional materials is a challenge because of the trade‐off between these two properties. Herein, a synthetic strategy is presented for enhancing the optical properties of CO2‐based polycarbonates by modifying the polymer's topological structure. Terpolymers with thiocarbonate and carbonate units randomly distributed in the polymers’ main chain were synthesized via the terpolymerization of cyclohexene oxide with a mixture of CO2 and COS in the presence of metal catalysts, most notably a dinuclear aluminum complex. DFT calculations were employed to explain why different structural sequence were obtained with distinct bimetallic catalysts. Varying the CO2 pressure made it possible to obtain terpolymers with tunable carbonate linkages in the polymer chain. More importantly, optical property studies revealed that terpolymers with comparable thiocarbonate and carbonate units exhibited a refractive index of 1.501 with an enhanced Abbe number as high as 48.6, much higher than the corresponding polycarbonates or polythiocarbonates. Additionally, all terpolymers containing varying thiocarbonate content displayed good thermal properties with Tg>109 °C and Td>260 °C, suggesting little loss in the thermal stability compared to the polycarbonate. Hence, modification of the topological structure of the polycarbonate is an efficient method of obtaining polymeric materials with enhanced optical properties without compromising thermal performance.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Randomly Distributed Sulfur Atoms in the Main Chains of CO₂‐Based Polycarbonates: Enhanced Optical Properties

et al. 2020

View full text Add to dashboard Cite

show abstract

“…Under these conditions,t he series of poly(monothiocarbonate)s P2 a-c with as electivity in thiocarbonate linkages of 70-82 %w ere prepared after 24 h( entries 3, 5, and 7, Table 2). [14] Thet ype and content of polymer linkages has ad rastic influence on the glass transition temperature (T g )o ft he polymer.A sageneral trend, T g significantly increased with the content of thioether-co-cyclic carbonate linkages.T he most impressive effect on T g was noted for the polymers prepared with DT2,for instance achange in T g from 61 8 8Cto 126 8 8Cw ith 19 and 99 %o ft hioether-co-cyclic carbonate linkages,respectively (entries 5and 4, Table 2). No polymerization was observed in the absence of DBU,e ven with 3mol % FA.…”

Section: Angewandte Chemiementioning

confidence: 99%

A Switchable Domino Process for the Construction of Novel CO₂‐Sourced Sulfur‐Containing Building Blocks and Polymers

et al. 2019

View full text Add to dashboard Cite

a-Alkylidene cyclic carbonates (aCCs) recently emerged as attractive CO 2 -sourced synthons for the construction of complex organic molecules.H erein, we report the transformation of aCCs into novel families of sulfur-containing compounds by organocatalyzed chemoselective addition of thiols,f ollowing ad omino process that is switched on/off depending on the desired product. The process is extremely fast and versatile in substrate scope,p rovides selectively linear thiocarbonates or elusive tetrasubstituted ethylene carbonates with high yields following a1 00 %a tom economy reaction, and valorizes CO 2 as arenewable feedstock. It is also exploited to produce al arge diversity of unprecedented functional polymers.I tc onstitutes ar obust platform for the design of new sulfur-containing organic synthons and important families of polymers.Carbon dioxide (CO 2 )i sa na ttractive abundant, safe,a nd renewable carbon source for the synthesis of organic cyclic carbonates.T oday,t hese molecules find many and diverse applications as intermediates for fine chemical synthesis, electrolytes in Li-ion batteries,p olar aprotic solvents,a nd monomers for the preparation of world-relevant polymers such as polycarbonates and polyurethanes. [1] The[ 3 + +2] cycloaddition of CO 2 to epoxides is the most popular and straightforward approach to five-membered cyclic carbonates [2] and, with the recent breakthroughs in their catalyzed transformations, [3] new CO 2 -based organic molecules with ahigh degree of complexity are now accessible. [4] a-Alkylidene cyclic carbonates (aCCs) are also rapidly emerging as another important class of industrially relevant CO 2 -sourced cyclic carbonates. [5] They are produced by catalytic carboxylative coupling of propargylic alcohols with CO 2 . [6] In contrast to the conventional five-membered cyclic carbonates,t he presence of an exocyclic vinylic group facilitates the regioselective ring-opening of the cyclic carbonate by various nucleophiles,l eading to new potentials in modern organic chemistry for the selective construction of novel molecules.The potential of aCCs for the preparation of new building blocks is enormous,b ut examples are still limited to b-oxocarbamates, b-oxocarbonates, b-hydroxy-1,3oxazolidin-2-ones, a-hydroxyketones,a nd 3-dialkylaminooxazolidin-2-ones. [7,8] Recently,s ome of us demonstrated their utility for the synthesis of functional polyurethanes and polycarbonates,o pening new perspectives for the design of advanced materials. [8] Ther ing-opening of aCCs by thiols is potentially attractive to drastically enlarge the scope of these CO 2 -based synthons but is surprisingly unexplored. It is expected to provide new relevant sulfur-containing products for both synthetic organic (e.g. thiocarbonates) and polymer chemistries (e.g.p oly(monothiocarbonates)). Thiocarbonates are notably important synthetic intermediates in organic chemistry [9] and are used as protecting groups for thiols. [10] Poly(monothiocarbonate)s are attractive polymers for optic applications due to the...

show abstract

“…38,46 1 H NMR spectra of both classes of material are resolved into the aromatic, methine and the methylene regions, each of which integrate as expected. 13 C{ 1 H} NMR spectra of the PUs show a single signal between 152 and 157 ppm, corresponding to the carbonyl environment within the carbamate moiety. 13 C{ 1 H} NMR spectra of PAs display two signals between 150 and 155 ppm, corresponding to the two distinct carbonyl environments within the allophanate moiety.…”

mentioning

confidence: 99%

Polyurethanes and Polyallophanates via Sequence-Selective Copolymerization of Epoxides and Isocyanates

et al. 2020

View full text Add to dashboard Cite

Aryl isocyanates are introduced as comonomers for ring opening copolymerization (ROCOP) with epoxides. Informed by studies of reaction kinetics, we show that divergent sequence selectivity for AB-and ABB-type copolymers can be achieved with a single dimagnesium catalyst. The resulting materials respectively constitute a new class of polyurethane (PU) and a new class of material featuring an unprecedented backbone structure, the polyallophanate (PA). The successful use of isocyanate comonomers in this way marks a new direction for the field of ROCOP, while providing distinct opportunities for expansion of PU structural diversity. Specifically, the methodology reported herein delivers PUs featuring fully substituted (tertiary) carbamyl nitrogen atoms, a structural motif that is almost inaccessible via extant polymerization strategies. Thus, in one step from commercially available comonomers, our methodology expands the scope of ROCOP and gives access to diverse materials featuring both privileged (PU) and unexplored (PA) microstructures.Controlled ring opening copolymerization (ROCOP) involving epoxide comonomers represents a significant accomplishment in the fields of catalysis and materials chemistry. By overcoming the synthetic challenges associated with selective alternate copolymerization, readily-available comonomers such as carbon dioxide, 1-3 its sulfur-analogs 4-15 or cyclic anhydrides 16 can be converted directly to valuable, biodegradable plastics such as poly(thio)carbonates (Scheme 1A) and polyesters. 17 Perhaps most notably, ROCOP strategies offer atom-economic access to materials with properties that can be readily tuned by varying both comonomers. While this advantage is regularly exploited in epoxide/cyclic anhydride ROCOP, 18 the same cannot be said for epoxide/heteroallene ROCOP where the scope with respect to heteroallene comonomers has remained limited to carbon dichalcogenides (CO2, COS or CS2). All materials synthesized via epoxide/heteroallene copolymerization must therefore be based on the (thio)carbonate linkage. Methods employing isocyanates as the heteroallene component would overcome this limitation 19,20 and provide concise access to polyurethanes (PUs), an iconic class of material with a market value predicted to exceed $79bn in 2023. 21,22 Current routes to PUs -including industrially ubiquitous copolymerization of diisocyanates with polyols -give secondary (NH) carbamyl linkages (Scheme 1B). There exists no general method for the direct synthesis of PUs featuring tertiary carbamyl linkages. 17a-c,22-25 Challenging post-polymerization N-H functionalization is thus necessary if all vectors of the PU chain are to be exploited. Scheme 1. Context and Strategic Blueprint for Copolymerization of Epoxides and Heteroallenes ASSOCIATED CONTENT Supporting InformationAdditional discussion, experimental procedures, kinetic data and simulations, and characterization data (hydrolysis studies, NMR spectra, GPC traces and DSC traces). This material is available free of charge via the Internet at...

show abstract

Synthesis of Chiral Sulfur‐Containing Polymers: Asymmetric Copolymerization of meso‐Epoxides and Carbonyl Sulfide

Cited by 65 publications

References 45 publications

Randomly Distributed Sulfur Atoms in the Main Chains of CO₂‐Based Polycarbonates: Enhanced Optical Properties

Randomly Distributed Sulfur Atoms in the Main Chains of CO₂‐Based Polycarbonates: Enhanced Optical Properties

A Switchable Domino Process for the Construction of Novel CO₂‐Sourced Sulfur‐Containing Building Blocks and Polymers

Polyurethanes and Polyallophanates via Sequence-Selective Copolymerization of Epoxides and Isocyanates

Contact Info

Product

Resources

About

Synthesis of Chiral Sulfur‐Containing Polymers: Asymmetric Copolymerization of meso‐Epoxides and Carbonyl Sulfide

Cited by 65 publications

References 45 publications

Randomly Distributed Sulfur Atoms in the Main Chains of CO2‐Based Polycarbonates: Enhanced Optical Properties

Randomly Distributed Sulfur Atoms in the Main Chains of CO2‐Based Polycarbonates: Enhanced Optical Properties

A Switchable Domino Process for the Construction of Novel CO2‐Sourced Sulfur‐Containing Building Blocks and Polymers

Polyurethanes and Polyallophanates via Sequence-Selective Copolymerization of Epoxides and Isocyanates

Contact Info

Product

Resources

About

Randomly Distributed Sulfur Atoms in the Main Chains of CO₂‐Based Polycarbonates: Enhanced Optical Properties

Randomly Distributed Sulfur Atoms in the Main Chains of CO₂‐Based Polycarbonates: Enhanced Optical Properties

A Switchable Domino Process for the Construction of Novel CO₂‐Sourced Sulfur‐Containing Building Blocks and Polymers