Diels-Alder反应合成四氢化邻苯二甲酸酐新工艺

用质量分数30％－60％丁二烯的C4混合烃与顺丁烯二酸酐进行双烯合成反应生成四氢化邻苯二甲酸酐（简称四氢苯酐）。实验确定了最佳工艺条件：反应温度130℃，反应时间30min，丁二烯与顺酐摩尔比1.2。在该条件下运转，产品总收率大于99％，其固相收率大于97％，粗产品精制后纯度大于99％，反应溶剂可回收循环使用。     

2,3,4,5-四苯基环戊-2,4-二烯酮的合成工艺研究

以1?3-二苯基丙酮和二苯基乙二酮为原料,无水乙醇为溶剂,在氢氧化钾(KOH)作用下经过2次Aldol缩合-消除反应,得到2?3?4?5-四苯基环戊-2?4-二烯酮。产物结构通过~1HNMR和ESI-MS鉴定。确定的最佳反应工艺条件为:n(二苯基乙二酮)∶n(1?3-二苯基丙酮)=1.1∶1,n(KOH)∶n(1?3-二苯基丙酮)=1∶4,反应温度为78℃,反应时间为50min。在此最佳条件下,产物的收率为88.5%。     

甲基苯基硅烷单体及其环硅氧烷的合成研究进展

综述了甲基苯基二氯硅烷和甲基苯基二烷氧基硅烷的合成方法及以其为原料制备甲基苯基环硅氧烷的工艺,总结了各种方法和工艺的优缺点,并对存在的问题和未来研究方法进行了探讨。     

含稠环基团的有机硅化合物及聚合物的研究 IV.含取代苊基有机硅烷的合成

利用乙烯基三乙氧基硅烷和烯丙基三乙氧基硅烷与苊式环戊二烯酮通过Ｄｉｅｌｓ－Ａｌｄｅｒ反应合成两种新的含取代苊基的有机硅化合物，并对新化合物进行了相应的组成和结构分析。     

八苯基环四硅氧烷用量对乙烯基硅油热稳定性的影响

采用八苯基环四硅氧烷(P4)与甲基乙烯基硅油共聚制备苯基乙烯基硅油,考察了P4的用量对乙烯基硅油热稳定性的影响。结果表明,随着P4用量的增加,苯基乙烯基硅油在傅里叶变换红外光谱谱图中的苯基特征吸收峰更加显著,动力黏度不断增大。在氮气中,甲基乙烯基硅油的质量损失分2个阶段,苯基乙烯基硅油的质量损失分3个阶段;而在空气中,二者的质量损失均为2个阶段。相比于甲基乙烯基硅油,苯基乙烯基硅油的热稳定性更佳,且随P4用量的增加,其热稳定性更好。当苯基乙烯基硅油中P4的质量分数大于50%后,继续增加P4用量,苯基乙烯基硅油的热稳定性提高有限。     

低粘度羟基封端聚甲基苯基硅氧烷的合成研究

以甲基苯基环硅氧烷(MPCS)和乙酸酐为原料,在大孔径强酸性阳离子交换树脂催化下开环聚合制备了乙酰氧基封端的聚甲基苯基硅氧烷(AcO-PMPS),AcO-PMPS在Na2CO3水溶液中水解制备了低粘度羟基封端的聚甲基苯基硅氧烷(HO-PMPS).研究结果显示,优化的聚合反应条件为:催化剂质量分数为18％～20％,反应温...     

苯基锗吡啶基羧酸酯的合成及表征

利用二或三苯基氯化锗与吡啶基羧酸钠反应，合成了9种苯基锗吡啶基羧酸酯。通过元素分析，红外光谱和核磁共振氢谱对其结构进行表征。     

羟基聚甲基苯基硅氧烷的合成

四川大学的李强等人在酸性条件下水解甲基苯基二乙氧基硅烷，水解产物在碱催化下与D4开环聚合，制得了系列高苯基含量羟基封端的聚甲基苯基硅氧烷低聚物。     

对称溴代间-三苯基苯的合成

以溴代苯乙酮为原料在四氯化硅乙醇(TCSEtOH)催化下合成了对称溴代间三苯基苯功能模块。     

侧基为苯环的改性环硅氧烷的合成及其对硅橡胶性能的影响

通过甲基二苯基硅烷(Me Ph_2Si H)改性四甲基四乙烯基环四硅氧烷(D_4~(Vi))制得了2种含有不同苯环侧基浓度的改性环硅氧烷,采用核磁共振表征了改性环硅氧烷,并研究了改性环硅氧烷对硅橡胶阻尼性能及物理机械性能的影响。结果表明,2种改性环硅氧烷分别为D_4~(Vi)分子中3个乙烯基基团与Me Ph_2Si H发生硅氢化反应的产物和D4Vi与Me Ph_2Si H完全硅氢加成反应的产物; 添加改性环硅氧烷能够提高硅橡胶的阻尼性能,且侧基浓度越大,硅橡胶的阻尼性能越佳; 添加含有活性乙烯基的改性环硅氧烷能够提高硅橡胶的物理机械性能,而无乙烯基、含有大空间位阻基团的改性环硅氧烷则会降低物理机械性能。     

马来酸酐和呋喃的Diels-Alder反应研究

本文详细考察了马来酸酐和呋喃的Diels-Alder反应.得出了最佳反应条件为：反应时间为16h、马来酸酐和呋喃最佳摩尔比5∶1、最合适的溶剂丙酮.产品的转化率达82.5％.用1HNMR进行了表征.     

月桂烯合成柑菁醛的研究

研究了利用月桂烯和丙烯醛经 Diels- Alder反应制取柑菁醛 ,探讨了反应物之比 (体积比 )、反应温度、反应时间等对产品得率的影响。结果表明工艺及设备简单、易行 ,稳定性好 ,产品得率≥ 80 %     

Synthesis of tung oil–diacrylate copolymers via the Diels‐Alder reaction and properties of films from the copolymers

Copolymers were synthesized from tung oil and 1,6 hexanediol diacrylate or 1,4‐butanediol diacrylate via the Diels‐Alder reaction. The copolymers were completely soluble in common laboratory solvents, and had very broad molecular weight distributions. The residual double bonds in the copolymers were used to cure films by oxidative means. The films had good solvent resistance, good gloss, and a reasonable hardness–flexibility balance. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2369–2375, 2001     

Self-healing polymers: evaluation of self-healing process via non-destructive techniques

The scope of this study is the real-time monitoring and evaluation of the healing process using novel testing procedures and non-destructive evaluation techniques. In this work, the healing approach that has been followed is that of the intrinsic Diels–Alder (DA) and retro-DA mechanism. Two polymers were used as adhesives in single lap-joint specimens that were subjected to static tensile loading. The healed specimens were subjected to the same testing procedure as the one before the first failure and the healing efficiency was assessed by the correlation of the experimental results prior and after healing. Acoustic emission and infrared thermography were employed with the destructive tests so as to monitor changes in the acoustic and the thermal profile between the virgin and the ‘healed’ specimen.     

Synthesis of Diels–Alder bond and hydrogen bond synergistic shape memory self-healing polyurethane elastomers

Self-healing materials exhibit the ability to repair damage and restore their function. Shape memory assisted self-healing (SMASH) materials are smart materials that automatically close localized microscopic cracks and repair these cracks by bonding damaged surfaces. A novel temperature-responsive SMASH polymer composite was established by introducing Diels–Alder bonds (D–A) in polyurethane. In this article, dynamic D–A produced by the polymerization of furfurylamine and 4,4’-bismaleimidodiphenylmethane was introduced into the molecular chain to enable the polyurethane elastomers containing D–A bonds to acquire self-repairing capability. The self-healing properties of the synthesized material were examined using polarized light microscopy, which revealed excellent fracture healing. The mechanical properties before and after healing were tested, in which the initial maximum tensile strength of the material could reach 7.9 MPa, and the maximum tensile strength after self-healing was 7.3 MPa, with a repair rate of 91.8%; the maximum elongation was 585.9%, and the maximum elongation after self-healing was 469.5%, with a repair rate of 80.1%. In addition, this material has excellent repair performance for microcracks of different scales, and the micromolten part of the surface after heating can fill the micrometer cracks, play the role of antiaging, and extend the service life of the material.     

Studies on the Biosynthesis of the Stephacidin and Notoamide Natural Products: A Stereochemical and Genetic Conundrum

The stephacidin and notoamide natural products belong to a group of prenylated indole alkaloids containing a bicyclo[2.2.2]diazaoctane core. Biosynthetically, this bicyclic core is believed to be the product of an intermolecular Diels–Alder (IMDA) cycloaddition of an achiral azadiene. Since all of the natural products in this family have been isolated in enantiomerically pure form to date, it is believed that an elusive Diels–Alderase enzyme mediates the IMDA reaction. Adding further intrigue to this biosynthetic puzzle is the fact that several related Aspergillus fungi produce a number of metabolites with the opposite absolute configuration, implying that these fungi have evolved enantiomerically distinct Diels–Alderases. We have undertaken a program to identify every step in the biogenesis of the stephacidins and notoamides, and by combining the techniques of chemical synthesis and biochemical analysis we have been able to identify the two prenyltransferases involved in the early stages of the stephacidin and notoamide biosyntheses. This has allowed us to propose a modified biosynthesis for stephacidin A, and has brought us closer to our goal of finding evidence for, or against, the presence of a Diels–Alderase in this biosynthetic pathway.     

Chemoselectivity in the Pd‐Catalyzed Cyclization of 1,6‐Enynes and Proof of the Relative Configuration of the New Stereogenic Centers

The dimerization of dienyne 6 with a palladole catalyst readily provides the bicyclic enyne rac‐ 7 . A second cyclization of the 1,6‐enyne substructure in rac‐ 7 works best with a hydropalladation catalyst and delivers rac‐ 8 . Diels‐Alder reactions of the latter finally lead to a crystalline product rac‐ 12 . A crystal structure analysis of rac‐ 12 allowed the determination of the relative configuration of all stereogenic centers formed in the dimerization of 6 .     

Synthesis and characterization of poly(ester-urethane-imide)s by Diels–Alder polyaddition

Poly(ester-urethane-imide)s were prepared by Diels–Alder polyaddition of 1,6-hexamethylene-bis(2-furanylmethylcarbamate) with various bismaleimides containing ester groups in the backbone. The Diels–Alder reaction was carried out in m-cresol, at 110°C, followed by thermal and chemical aromatization of tetrahydrophthalimide intermediates. The monomers and polymers were characterized by IR, ¹H-NMR spectroscopy and elemental analysis. Thermal properties of the polymers were investigated by differential scanning calorimetry and dynamic thermogravimetric analysis.     

Synthesis and properties of self-healing cross-linked nonisocyanate polyurethanes from biobased diglycerol bis(cyclic carbonate)

A simple and green method was established to prepare self-healing cross-linked nonisocyanate polyurethanes (SH-cNIPUs) from biobased diglycerol bis(cyclic carbonate) (DGDC). Two nonisocyanate polyurethane prepolymers with furan terminal groups (tFU-NIPUs) were synthesized through a ring-opening reaction of DGDC with furan methylamine and trimethylolpropane tris(poly[propylene glycol], amine terminated) ether, or tris(2-aminoethyl) amine under mild conditions. The SH-cNIPUs were prepared via a Diels–Alder reaction between tFU-NIPUs and a bismaleimide. SH-cNIPUs were characterized by ATI-FTIR, ¹H NMR, differential scanning calorimetry, polarized optical microscope, and tensile strength after being damaged and healed. SH-cNIPUs with glass transition temperature from 8 to 49°C, tensile strength up to 21 MPa, and self-healing efficiency from 67 to 80% were successfully synthesized.