Journal of Molecular Catalysis A: Kemi
bind 424,
1. December 2016
s. 77-84
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https://doi.org/10.1016/j.molcata.2016.08.017access to rights and content
Abstract
A series of solid bases were synthesized as catalysts for the direct transesterification of diphenyl carbonate (DPC) with aliphatic diols to synthesize high molecular weight aliphatic polycarbonate (APC). The physicochemical properties of these catalysts were characterized by various techniques to show the relationship between catalyst structure and catalytic performance. Among all the solid bases and magnesium compounds tested in this study, MgO prepared by a simple coprecipitation method was found to be the most active catalyst. High molecular weight poly(1,4-butylene carbonate) (PBC) can be readily obtained in this MgO, where MwUnder optimized conditions it can reach 182 200g/mol. In addition, scale-up experiments in a 5.0 L stainless steel reactor also confirmed the reliability of this transesterification process using MgO as a catalyst, yielding the largest MwPBC has values as high as 208,600 g/mol. Moderately and strongly basic sites were found to be responsible for this transesterification process. At the same time, the strongly basic sites are also beneficial for the degradation and depolymerization of the resulting PBC, resulting in MwAnd performance at higher temperatures. Furthermore, based on experimental results and related literature, this process suggests a plausible reaction mechanism to activate diols by extracting protons from MgO basic sites.
graphic summary
MgO was found to be an effective catalyst for the synthesis of high molecular weight aliphatic polycarbonates by direct melt-state transesterification of DPC and aliphatic diols. The catalytically active sites for this process are attributed to the presence of basic sites of moderate and strong strength on the solid base.
introduce
Aliphatic polycarbonates (APC) have been widely used in biomedical fields due to their excellent biocompatibility and bioreactivity [1]. Due to their good resistance to hydrolysis and oxidation, they can also be used as a raw material in the water-based polyurethane industry [2]. More importantly, with the number average molecular weight (Mw) above 70,000 g/mol are also considered promising substitutes for petrochemical monomers as biodegradable plastics [3], [4]. Traditionally, these APCs can be synthesized by copolymerization of CO2Ring-opening polymerization with epoxides and cyclic carbonates. Unfortunately, these routes still have several drawbacks, such as the poor structure of the resulting polymers, the low efficiency of existing catalysts, and the high cost of raw materials, which limit the large-scale production and application of these APCs [5]. , [6] .
Fusion transesterification of dimethyl carbonate (DMC) with aliphatic diols via a two-step polycondensation route is considered a clean and sustainable synthetic route for the preparation of APCs with various structures, as this route is an efficient process without solvents [7], [8], [9], [10]. Recently, in our previous work, we have also developed a simpler one-pot method by replacing DMC with high-boiling diphenyl carbonate (DPC), where the phenol by-product can be easily separated and recycled [11]. Whichever process we choose, an efficient catalyst is a key factor in preparing APC with satisfactory Mwworth. Therefore, a large number of compounds, including metal salts [8], [11], [12], [13], BMIM-2-CO2[10], titanium dioxide2/ silica2(PVP) (TSP-44) [4], [7], organic bases [14] and even enzymes [15], have shown great promise for this reaction. So far, the most effective catalysts proposed for this process are limited to homogeneous basic catalysts [8], [12]. However, thorny problems associated with such strong bases are the presence of unwanted side reactions, and residue from these catalysts can also reduce the thermal stability of the polymer. Furthermore, the structure-activity correlations of these basic catalysts in this process have not been well clarified. Under such circumstances, it is highly desirable to develop a new catalyst that can provide excellent activity and a good understanding of its mechanism of action in the transesterification reaction.
Recently, magnesium compounds have been widely used as catalysts for the synthesis of sustainable polymers from renewable resources [16]. In particular, MgO, as a typical solid base catalyst, has been widely used in many transesterification processes. Using triblock copolymers as soft templates, Lee et al. A series of MgO was prepared via a surfactant-assisted route, which showed excellent catalytic performance in the transesterification of DMC with glycerol for the synthesis of glycerol carbonate (GLC) [17]. Among them, the catalytically active sites are attributed to the highest concentration of basic sites on their surface. K-doped MgO catalysts were also reported by Lago et al. For the synthesis of biodiesel by transesterification of soybean oil with methanol [18]. In addition, magnesium-based mixed oxides such as Mg-Al mixed oxides have been shown to be capable of catalyzing this reaction, where the basic site concentration, specific surface area, and size of the MgO crystallites are responsible for its excellent activity. [19] Di Serio and his colleagues found that MgO was also the best single catalyst for the transesterification of dimethyl terephthalate with ethylene glycol to produce polyethylene terephthalate (PET) [20]. And the obtained PET polymer has chemical and physical properties very close to commercial samples. Furthermore, MgO-catalyzed transesterification is often used as a valuable tool for polymer modification due to its non-toxicity and low cost [21]. Furthermore, MgO itself is an excellent inorganic filler for many polymers. The addition of MgO can not only improve their mechanical properties, but also give them new application properties [22], [23].
In this work, we also found that MgO exhibited significantly higher activity than other solid bases and magnesium compounds for the direct transesterification of DPC with aliphatic diols to synthesize APC. In combination with various characterization results, the relationship between catalyst structure and catalytic performance was investigated by comparing MgO with other solid bases. Furthermore, a reaction mechanism was proposed that could involve basic site facilitation.
partial fragment
Catalyst material and preparation.
Commercial DPC was purified by recrystallization from absolute ethanol before use. All aliphatic diols were dehydrated by distillation over calcium hydride under dry nitrogen. Other reagents were purchased from Chengdu Kelong Chemical Reagent Co., Ltd. (China) and used directly without further processing.
Two types of MgO were synthesized in this study: direct thermal decomposition of Mg(NO)3)26 timer2O (MgO-T) Suma Mg(NO3)26 timer2of y na2carbon monoxide3(MgO-P). Directly
catalyst detection
The typical performance of various solid base catalysts in the transesterification of DPC with BD under the given conditions is summarized in Table 1. It can be seen that ZrO2, both MgO-T and CaO are active for this reaction under the same conditions, giving PBC an Mw21,300, 36,600 and 47,800 g/mol. However, the polymerization rate of ZnO is so low that MwTheir PBC aggregates could not be detected under the given conditions. In addition, the catalytic performance and preparation
Finally
The synthesis of high molecular weight APCs by transesterification of DPCs with aliphatic diols can be carried out over solid base catalysts. MgO prepared by a simple coprecipitation route showed the best performance among the solid bases and magnesium compounds studied. The solid-base active sites for this reaction were assigned to be moderately strong rather than acidic, increasing with decreasing calcination temperature. at the same time,
gracias
This work was financially supported byNational Program to Support Key Science and Technology(2013BAC11B05),Jiangsu Province R&D Innovation Key Plan(Concession no.BE2015055) ySichuan Science and Technology Support Program(2016GZ0228).
- ZMliusale.
J. Indiana Meadows. Chemical.
(2015)
- X.G.opensale.
Request Catalan. environment b.
(2014)
- F.S.H.Junde sailorsale.
Request Catalan. A-Gen.
(2011)
- WYopensale.
J. Moore. Catalan. A chemistry.
(2005)
- general motorsZhaosale.
J. Moore. Catalan. A chemistry.
(2010)
- JI.Cosimosale.
J. Catalan.
(1998)
- D.Wusale.
Catalan. commune.
(2008)
- METRO.seriouslysale.
J. Moore. Catalan. A chemistry.
(2004)
- METRO.Hayeksale.
Chemical. project. j.
(2015)
- A.P.C.Teixeirasale.
Chemical. project. j.
(2013)
Request Catalan. A-Gen.
(2014)
polymer. Chemical.
(2016)
J. Indiana Meadows. Chemical
(2016)
programming. polymer. science.
(2014)
programming. polymer. science.
(2012)
green chemistry.
(2016)
Evening. Common.
(2015)
polymer. in t.
(2011)
programming. Chemical.
(2011)
clean. Apply for Chemistry.
(2011)
makromolekyle
(2013)
grind CO
2 Functional polymers as raw materials.2023, The circularity of plastics: Sustainability, new materials and added value from plastic waste
Artificial carbon dioxide (CO2) is currently the largest contributor to global warming. With its abundant non-toxic and renewable properties, CO2As a feedstock for the synthesis of polymers, it offers a promising path towards a circular carbon economy. This chapter highlights recent advances in CO2based on polymers, with particular emphasis on the commercially important polycarbonate (PC) and polyurethane (PU). Industrially viable approaches will be presented, complemented by discussions on bridging the gap between academia and industry.
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Citatuddrag:
In addition, the catalytic performance of four representative organic and metallic catalysts, including LiAcac, Cs2CO3, TBD and DBU, which were highly effective for polymerization processes as reported in the literature [24,26,35,36], were investigated. However, compared to [Bmim][CH3CHOHCOO], the Mw value of PTTIC is relatively low (see Table 1, entries 6–9), which may be because strong basic sites of metals and organic bases can promote decomposition and depolymerization by PTTIC. formed at high temperature [37]. Therefore, [Bmim][CH3CHOHCOO] was chosen as the most suitable catalyst for further research due to its efficient activation of carbonyl groups in DPC and hydroxyl groups in ISB and TTEG.
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Diethyl carbonate was reacted with phenol or 1,6-hexanediol over 5 mol% tetra-tert-butyldilithium zincate (TBZL) as catalyst at 25 or 70°C. Under these conditions, no exchange reaction occurs with phenol, but it does with 1,6-hexanediol. Therefore, the polycondensation of diphenyl carbonate with 1,6-hexanediol was investigated. As expected, poly(hexamethylene carbonate) was obtained without removing the phenol by-product. As the polymerization temperature increased, the conversion rate reached more than 99%. Furthermore, 1,5-pentanediol and 1,9-nonanediol are also suitable diols for polycondensation. Aliphatic polycarbonates with a number average molecular weight of 10,000 or higher are obtained under optimal polymerization conditions. The polycondensation catalyzed by TBZL was faster than that catalyzed by titanium tetraisopropoxide, which was used as a general catalyst for the polycondensation of diesters, dialkyl carbonates, and diphenyl carbonates with diols. Polycondensation with TBZL was performed at atmospheric pressure in the presence of the by-product phenol. This polymerization system is expected to be applicable to various diols.
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Citatuddrag:
Due to the harsh reaction conditions, the production of high molecular weight PIC requires suitable catalysts for the melt polycondensation process. To date, basic catalysts have been shown to be more effective for PIC synthesis [5,30,31]. Lee et al. [29] synthesized PIC by melt polycondensation of isosorbide with DMC using lithium acetylacetonate as a catalyst.
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Synthesis and characterization of biodegradable multiblock poly(carbonate coesters) containing biobased monomers
2017, Polymers
Citatuddrag:
Compared to aliphatic polyesters, aliphatic polycarbonates (APC) are more suitable for biomedical applications due to the absence of acidic compounds during in vivo degradation [1,2]. Among the resulting APCs, poly(butylene carbonate) (PBC), which benefits from its good reach and competitiveness, actually plays a role as one of the most promising biodegradable plastic candidates to solve the white pollution problem. It plays an important role, especially in research on packaging bags and agricultural films in this field [3-5]. However, the thermal stability and crystallization rate of PBC remain somewhat intrinsic for industrial applications [6,7].
Multiblock polycarbonate coesters (PBC-PBSe) (PBSe-OH) use 1,6-hexamethylene diisocyanate (HDI) as a chain extender. The chemical structure, molecular weight, crystallization behavior, thermal, degradation, and mechanical properties of the copolyesters were characterized by proton NMR spectroscopy (1H NMR), Fourier transform infrared (FT-IR) spectroscopy, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), hydrolytic degradation, and mechanical testing. The results showed that the introduction of the PBSe segment not only significantly increased the PBC crystallization rate, but also showed the same crystallization mechanism in the investigated crystallization temperature range, despite the variation in the content of the PBSe segment. Furthermore, the thermal stability and the hydrolytic degradation rate of the PBC-PBSe multiblock copolymers increased with increasing PBSe content. The mechanical properties of the copolymers can be adjusted by changing the composition of the feed.
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Power Magazine, volume 318, 2016, p. 228-2
The effectiveness of cresyl carbonate and diphenyl carbonate alone or in combination with methylene methane disulfonate and tris(-trimethylsilyl) phosphite as electrolytic additives has been systematically investigated on LiNi.0,8mangan0,1limited liability company0,1Europa2/ Graphite bag battery. Experiments performed include ultra-high-precision coulometric methods, electrochemical impedance spectroscopy, automated storage, gas evolution measurements, and long-term cycling. The results show that the addition of methylphenyl or diphenyl carbonate increases Coulombic efficiency, reduces capacity slip at the end of charge, reduces self-discharge rate during storage, and improves capacity retention over long-term cycles compared to with cells containing a control electrolyte. rate [ lithium phosphate 1M6Ethylene carbonate: methyl ethyl carbonate 3:7] or control electrolyte containing 2% vinylene carbonate. 1% diphenyl carbonate appeared to be the best of the systems tested. Based on these experiments, diphenyl carbonate appears to be a very beneficial additive for improving the performance of high-voltage Li-Ni batteries.0,8mangan0,1limited liability company0,1Europa2/Graphite bacteria.
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Letters of inorganic chemistry, binding 90, 2018, face 57-60
Ancho3CH2DEC (diethyl carbonate) catalyzed by ONa and α,ω-alkanediols (1,4-butanediol (BD), 1,5-pentanediol (PD) or 1,6-hexanediol (HD)) in a two-stage transesterification process steps using M for the production of semicrystalline poly(alkylene carbonate)norte(number average molecular weight) max. 104g/mol In the first stage transesterification reaction, the equal [
OC(O) y2CH3]/[OH] The molar ratio between the obtained oligomers should be confirmed, while the chain growth betweenThe chopper effect imparted by the combined OH and ethylene carbonate oligomers and incomplete diols and hydroxycarbonates acts synergistically during the second transesterification process.Investigation article
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European Polymer Journal, binding 84, 2016, face 799-811
Bis(cyclic carbonates) based on sugar alcohols such asd- mannitol,d- Sorbitol and bis(trimethylolpropane) were used as monomers to prepare various crosslinked poly(carbonate-urethane) (PCU) that do not require phosgene or toxic isocyanate monomers. In our proposed method, the cross-linked structure of poly(urethane carbonate) is obtained by reacting amine-terminated oligo(hydroxycarbamate) with six-membered bis(cycliccarbonate), followed by a residual six-membered cyclic carbonate end group. Depending on the molar ratio of aliphatic diamines and five to six membered bis(cyclic carbonates) used, the resulting non-isocyanate polyurethanes (NIPU) have elastic or rigid properties.
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Palladium(II)/bis(carbide)iron ion complexes for catalytic oxidative carbonylation to form diphenyl carbonate
Journal of Organometallic Chemistry, enlace 849-850, 2017, lado 195-200
Carborane-based sandwich iron complexes, [n-Bu4N]{Fe(3,3')-[1,2-(PPh2)2-1,2-C2Other9H9]2}, synthesized with a yield of 53.1%. PdAc catalyst complex2/[Zheng Bu4N]{Fe(3,3')-[1,2-(PPh2)2-1,2-C2Other9H9]2} turned out to be very active for the oxidative carbonylation of phenol with formation of diphenyl carbonate (DPC). A DPC yield of 46% and a turnover number (TON) of 511 was obtained in 4 h using the compound at 110 °C. For comparison, the reaction was also studied using the PdAc composite catalyst.2/Mn(CA)3, Propionic acid2/Fe(acac)3, Propionic acid2/Cobalt (AC)3y PdAc2/That3(acac = acetylacetone) under the same conditions of temperature and pressure. DPC yield was determined by gas chromatography with flame ionization detector (GC-FID). All new products are characterized by elemental analysis and by1H,13C,11banda31Espectroscopia P NMR y FT-IR.
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Preparation of MoO3/SiO2 and its catalytic performance for the disproportionation of cresyl carbonate to diphenyl carbonate
Journal of Molecular Catalysis A: Chemistry, link 398, 2015, side 248-254
molybdenooxido3/ silica2Prepared by various methods and used as a heterogeneous catalyst for the liquid phase disproportionation of cresyl carbonate (MPC) to diphenyl carbonate (DPC). XRD, FT-IR and BET characterizations showed that the preparation method had a significant influence on the structural properties and catalytic activity of MoO.3/ silica2.Molybdenoxide3/ silica2The one prepared by the combined sol-gel method and hydrothermal treatment (M-SGH) exhibited the highest catalytic activity due to the high MoO dispersion.3, obtained a large specific surface area and large pores. Under optimal conditions (200°C, 2 hours, using 0.9 g of catalyst and MoO3When the loading amount was 15% by weight, the MPC conversion rate reached 72.8% and the DPC yield was 71.4%. In addition, M-SGH exhibits excellent reusability and reproducibility. After seven consecutive runs, MPC conversion dropped slightly from 72.8% to 56%. The formation of carbonate species on the catalyst surface is the main reason for the decrease in activity. The deactivated M-SGH can be easily regenerated by calcination at 500 °C in air, and the catalytic activity of the regenerated M-SGH is fully restored to the same as the new one.
Investigation article
Effect of coordinating groups on the properties of organotitanium compounds catalyzed by disproportionation of cresyl carbonate to diphenyl carbonate
Applied Catalysis A: A Review, Link 540, 2017, Side 1-6
The mismatch between cresyl carbonate (MPC) and diphenyl carbonate (DPC) catalyzed by organotitanium compounds with different coordination groups was systematically investigated. The results of molecular structure analysis, catalytic performance evaluation, and chemical computational studies indicated that the electronic effect and steric hindrance of the coordination group jointly affect the active Ti center, thereby affecting the catalytic performance of the catalyst. The influence of electronic effects is more important than steric hindrance. The order of catalytic activity is Ti(O-iC).3H7)4> you (OC6H5)4> you (OC4H9)4>Titanium dioxide (OOCCH3)2> Titanium Dioxide (CA)2>CP2titanium chloride2, sum Ti(O-iC3H7)4Due to the appropriate steric hindrance and the electronic effect of the coordination group, it exhibits the best catalytic performance. Under optimal conditions (n(Cat.)/n(MPC)=0.04, 180 °C for 3 h), MPC conversion reached 90.4 % and DPC selectivity reached 99.6 % in comparison with other reported catalysts. In addition, the catalyst is low cost, non-toxic and readily available on the market, and the catalyst system is simple to operate and easy to control, which is beneficial for future industrial applications. In addition, a reaction mechanism was also proposed in which this process can be catalyzed by organotitanium compounds with Lewis acids.
OC(O) y2CH3]/[© 2016 Elsevier B.V. All rights reserved.