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用乳化-溶剂蒸发法制备了聚己内酯-聚丙交酯-聚醚三元无规共聚物微粒,且与用相同方法制备的聚己内酯(PCL)和聚己内酯-聚醚嵌段共聚物微粒的形态进行了比较。他材料的亲水性,以及三元无规共聚物中亲水性聚醚链段的长度及含量对所形成微粒形态的影响。研究结果表明,随着聚合物由疏水性向亲水性转变,所生成微粒的形态则从光滑、多孔、到不规则变化。证明了三元无规共聚物多孔向亲水性一粒的形成是由于亲水的聚醚链段向水相 相似文献
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聚己内酯-聚丙交酯-聚醚三元共聚高分子微粒及其降解的研究 总被引:2,自引:0,他引:2
用乳化- 溶剂蒸发法制备了聚己内酯- 聚丙交酯- 聚醚三元无规共聚物微粒,且与用相同方法制备的聚己内酯(PCL) 和聚己内酯- 聚醚嵌段共聚物微粒的形态进行了比较,讨论了材料的亲水性,以及三元无规共聚物中亲水性聚醚链段的长度及含量对所形成微粒形态的影响。研究结果表明,随着聚合物由疏水性向亲水性转变,所生成微粒的形态则从光滑、多孔、到不规则变化。证明了三元无规共聚物多孔微粒的形成是由于亲水的聚醚链段向水相取向所致。在37 ℃、pH7 .4 的缓冲液中进行了三元无规共聚物微粒的降解,结果表明,随着降解时间的延长, 三元无规共聚物的分子量逐渐下降,且其中的聚醚链段含量有明显的降低。 相似文献
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离子液体支载稀土催化剂催化 2,2-二甲基-三亚甲基碳酸酯均聚及其与ε-己内酯的共聚 总被引:1,自引:0,他引:1
首次合成了离子液体支载稀土催化剂,并探讨了其催化2,2-二甲基-三亚甲基碳酸酯(DTC)均聚及其与ε-己内酯(ε-CL)的共聚,结果表明该新型催化剂能有效地催化DTC的均聚及其与ε-CL的共聚.研究了不同稀土以及加料顺序等反应条件对聚合的影响,发现轻稀土的催化活性比重稀土高,其中离子液体支载La催化剂的催化活性最高,而通过控制不同的加料顺序可以制备DTC和ε-CL的无规及嵌段共聚物.对共聚物结构进行了表征. 相似文献
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官能团化己内酯与丙交酯无规共聚物的合成与降解性能 总被引:1,自引:1,他引:0
研究了官能团化新型己内酯单体的合成及其与丙交酯无规共聚物的降解性能. 首先, 环己酮和N-异丙基丙烯酰胺通过Michael加成反应合成了2-(N-异丙基酰胺乙烯基)-环己酮; 然后, 以间氯过氧化苯甲酸为氧化剂, 通过Baeyer-Villiger氧化反应, 制备带有酰胺官能团的己内酯单体6-(N-异丙基酰胺乙烯基)-ε-己内酯; 最后, 在异辛酸亚锡[Sn(Oct)2]的催化下与丙交酯开环聚合, 得到新型己内酯与丙交酯的无规共聚物. 采用1H NMR, SEC和DSC表征了聚合物的结构和热力学性能. 同时通过黏度法、失重法和SEM对该聚合物的降解性能进行了表征. 结果表明, 该共聚物的降解速率明显增快, 材料降解2个月后, 材料的质量损失达到28.1%, 特性黏度降低近40%. 相似文献
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《功能高分子学报》2020,(1)
以一种新型膦胺类稀土金属钇配合物(2,4,6-Me_3C_6H_2NPPh_2)Y(CH_2C_6H_4NMe_(2-o))_2为催化剂,当十三烷二酸环乙撑酯(EB)与催化剂的物质的量之比为200时,采用一锅法在室温条件下实现了EB分别与δ-戊内酯和ε-己内酯的共聚合,制备了EB含量递变的聚酯共聚物。利用核磁共振(NMR)、差示扫描量热(DSC)、热重分析(TG)和广角X射线衍射(WAXD)等对共聚物进行了表征,研究了共聚物的序列结构、结晶性能及热性能。结果表明:反应24 h单体转化率即可达80%~90%。所得共聚物具有明显的嵌段结构,无规度(R)低(0.25~0.36),且嵌段结构可显著提升共聚物的热稳定性。 相似文献
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用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%. 相似文献
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Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction
Laurent Gavara Thomas Boisse Jean-Pierre Hénichart Adam Daïch Philippe Gautret 《Tetrahedron》2010,66(38):7544-5571
In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments. 相似文献
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The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula. 相似文献
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Rebecca J. Burton Mandy L. CrowtherNeal J. Fazakerley Shaun M. FilleryBarry M. Hayter Jason G. KettleCaroline A. McMillan Paula PerkinsPeter Robins Peter M. SmithEmma J. Williams Gail L. Wrigley 《Tetrahedron letters》2013
The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines. 相似文献
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KMnO4-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields. 相似文献
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N. A. Nedolya 《Chemistry of Heterocyclic Compounds》2008,44(10):1165-1219
The review contains a concise historical account and information on the most significant researches undertaken by the staff
at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry
of Heterocyclic Compounds.
Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008. 相似文献
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Regiospecific and direct imidation of the methyl C(sp3)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products. 相似文献
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《Tetrahedron》2014,70(21):3377-3384
The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative. 相似文献
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Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields. 相似文献