甲基吡喃的合成

介绍了以多聚甲醛、间戊二烯为原料在四氢呋喃中BF3-乙醚溶液催化作用下进行Diels-Alder反应,合成2-甲基-5,6-二氢-2H吡喃的方法。考察了催化剂和溶剂、反应温度、时间等因素对收率的影响。结果表明,在多聚甲醛用量23g,间戊二烯91mL,BF3乙醚溶液1.5～2．0g．四氢呋喃40～50g,反应温度140～150℃,时间4h,常压条件下,收率可达52％。此合成工艺的成功,在一定程度上为顺-3-己烯-1-醇在国内的工业化生产奠定了基础。     

Improved “cure on demand” of aromatic bismaleimide with thiol triggered by retro-Diels-Alder reaction

This study focuses on the synthesis of new liquid aromatic bismaleimide monomers in order to improve self-curing on demand(SCOD)systems previously based on aliphatic bismaleimides.These SCOD systems are based on Diels-Alder(DA)/retro-DA reactions.The syntheses of new different aromatic bismaleimides with ester and amide bonds are presented.These maleimides have been protected using DA reaction and characterized by 1H NMR analysis to determine protection rate and diastereomer ratios.The retro-DA reactions of both aromatic and aliphatic DA adducts in presence of thiol molecules were studied.Kinetic analysis was monitored by 1H NMR and compared to model study.Finally,both aromatic and aliphatic bismaleimides-based polymers were synthesized with 2-mercaptoethyl ether and thermal properties of polymers were compared.The glass transition temperature values ranged from–20°C to 14°C and very good thermal stabilities were observed(up to 300°C).     

基于Diels-Alder动态共价键的含PEGDE片段自修复环氧树脂性能研究

用含双烯体结构的呋喃甲胺，将硬段为双酚A型E-51环氧树脂(EP)和软段为PEGDE连接成线性大分子，并与含亲双烯体结构的双马来酰亚胺反应，制备出含热可逆Diels-Alder(DA)反应的软-硬-软结构的本征型自修复环氧树脂(EP-DA)。通过FTIR、DSC、TGA和电子万能试验机，对EP-DA结构和性能进行了表征。结果表明：DA动态共价键成功引入EP-DA，且DA正、逆反应的温度分别是60℃、122℃。当EP-DA链段中的PEGDE和EP含量各占50%时，其耐热性和拉伸强度达到最佳。EP-DA还具有良好的再加工性能和多次自修复性能，受损试样在60℃下修复4 h后，裂纹基本愈合，且第一次修复率可达88. 41%，同一试样经过三次修复后，其修复率仍可达68%以上。     

改性活性白土催化油酸合成二聚酸

以油酸为原料,活性白土为催化剂合成二聚酸。利用HPLC方法和正交实验考察了适宜的工艺条件。实验结果表明,优化的工艺条件为:常压、反应温度240℃、反应时间6 h、活性白土用量为油酸的12%(w)、Li Cl用量为油酸的1.2%(w),在此条件下二聚酸的收率为34.6%。采用路易斯酸和有机化合物对活性白土进行无机和有机改性,并研究了路易斯酸的类型和有机插层对油酸常压聚合生成二聚酸的影响。实验结果表明,随路易斯酸性的增强,二聚酸的收率逐渐增加,适宜的路易斯酸为Al Cl3,用量为活性白土的3.3%(w),二聚酸收率可提高至55.9%。用十六烷基三甲基溴化铵改性活性白土时,适宜的用量为活性白土的0.6%(w),二聚酸收率为54.5%。     

Polyhydroxyesterimides from Renewable Resources: Synthesis,Characterization, Properties

Novel polyhydroxyesterimides were prepared by the reaction between diglycidyl monomers and diimidodiacids at the molar ratio 1/1 in the presence of triethylbenzylamonim chloride as catalyst. Diimidodiacids (DIMDA) were obtained from Diels-Alder adduct of resin acids with maleic anhydride and two aromatic diamines, at the molar ratio 1:2. The chemical reactions between the diglycidyl monomers (diglycidylether of bisphenol A -DGEBA and diglycidyl ether of hydroquinone–DGEHQ) and diimidodiacids were monitored by using differential scanning calorimetry (DSC). The chemical structures of the obtained monomers and polymers were established by means of elemental analysis, FT-IR, ¹H-NMR, and ¹³C-NMR methods. Thermal stability of the obtained polymers was also investigated and showed that they are reasonably thermostable.     

The first example of a domino Diels-Alder/retro-Diels-Alder reaction of 1,3-dienic δ-sultones with alkynes: a simple synthesis of m-terphenyl dicarboxy derivatives from 4,6-diphenyl-[1,2]oxathiine 2,2-dioxide

[1,1′;3′,1′′]Terphenyl-4′,5′-dicarboxylic acid derivatives were prepared from 1,3-dienic δ-sultone 4,6-diphenyl-[1,2]oxathiine 2,2-dioxide via Diels-Alder/retro-Diels-Alder reaction with dimethyl acetylenedicarboxylate under thermal, microwave or high-pressure activation.     

Evaluation of proton-conducting membranes for use in a sulfur dioxide depolarized electrolyzer

The chemical stability, sulfur dioxide transport, ionic conductivity, and electrolyzer performance have been measured for several commercially available and experimental proton exchange membranes (PEMs) for use in a sulfur dioxide depolarized electrolyzer (SDE). The SDEs function is to produce hydrogen by using the Hybrid Sulfur (HyS) Process, a sulfur-based electrochemical/thermochemical hybrid cycle. Membrane stability was evaluated using a screening process where each candidate PEM was heated at 80 °C in 60 wt% H₂SO₄ for 24 h. Following acid exposure, chemical stability for each membrane was evaluated by FTIR using the ATR sampling technique. Membrane SO₂ transport was evaluated using a two-chamber permeation cell. SO₂ was introduced into one chamber whereupon SO₂ transported across the membrane into the other chamber and oxidized to H₂SO₄ at an anode positioned immediately adjacent to the membrane. The resulting current was used to determine the SO₂ flux and SO₂ transport. Additionally, membrane electrode assemblies (MEAs) were prepared from candidate membranes to evaluate ionic conductivity and selectivity (ionic conductivity vs. SO₂ transport) which can serve as a tool for selecting membranes. MEAs were also performance tested in a HyS electrolyzer measuring current density vs. a constant cell voltage (1 V, 80 °C in SO₂ saturated 30 wt% H₂SO₄). Finally, candidate membranes were evaluated considering all measured parameters including SO₂ flux, SO₂ transport, ionic conductivity, HyS electrolyzer performance, and membrane stability. Candidate membranes included both PFSA and non-PFSA polymers and polymer blends of which the non-PFSA polymers, BPVE-6F and PBI, showed the best selectivity.     

Synthesis,Characterization and Glass Reinforcement of Poly(Ester Amido Imide)s

Poly(ester amido imide)s (PEAI)s (IIIa–e) were prepared by the intermolecular Diels-Alder (DA) reaction of bismaleimide (II) having epoxy resin segment with various bisfurans (Ia–e) having amide bridge. The DA reaction was carried out with tetrahydrofuran as a solvent, as well as in bulk, followed by aromatization of DA polyadduct intermediates in the presence of acetic anhydride. All the resultant polymers, designated as poly(ester amido imide)s (PEAI)s, were characterized by elemental analysis, number average molecular weight, IR spectral studies and thermogravimetry. The PEAIs exhibit good thermal stability. Bismaleimide (II) and bisfurans (Ia–e) were polymerized (at 150 ± 10°C) by in situ DA intermolecular reaction into moderately thermally stable PEAIs. The glass fiber-reinforced composites (i.e., laminates) of all PEAIs were prepared and characterized by their chemical resistance and mechanical properties.     

Reversible releasing of arms from star morphology polymers

Reversible thermally induced arm release from a star polymer morphology was prepared which consists of furanic functional core and maleimide functional arm which are attached or detached via Diels-Alder (DA) reversible reactions. This approach allows the reversible bonding and debonding at 35-40 °C (DA) and 90-100 °C (retro-DA). The covalent reversibility of this process consists of 7 cycles of the DA and retro-DA reactions.     

维生素K_2(20)的全合成

以甲萘醌为起始原料,经Diels-Alder反应,烷基化反应,逆Diels-Alder反应3步合成了具有药理活性的维生素K2(20)。与传统的直接烷基化法和格氏试剂法相比,该方法收率高、容易操作、反应条件温和。总收率59.1%。中间体及目标化合物Ⅺ经IR,1HNMR,13CNMR,MS确证。