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直接酯化法合成聚2,5-呋喃二甲酸乙二酯 总被引:4,自引:3,他引:1
以2,5-呋喃二甲酸(FDCA)和乙二醇(EG)为原料,草酸亚锡为催化剂,采用直接酯化法制备了聚2,5-呋喃二甲酸乙二酯(PEF)。考察了酯化反应、酯化产物、缩聚反应及缩聚产物的影响因素,结果表明,草酸亚锡在该体系中既可催化酯化反应又可催化缩聚反应,当n(FDCA)∶n(EG)=1∶1.6、草酸亚锡摩尔分数为0.1%、酯化温度为210℃、缩聚温度为240℃、缩聚反应时间为480 min、磷酸三甲酯摩尔分数为0.03%时,酯化程度最高(酯化产物的酸值在94%以上),缩聚产物相对分子量最高(比浓粘度达到1.29 dL/g),端羧基含量最低(34.3 mol/t);采用FTIR和1H NMR对目标产物的结构进行了表征。 相似文献
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《化学研究与应用》2016,(7)
用甲苯作带水剂,季戊四醇和油酸在对甲苯磺酸催化下反应合成了季戊四醇四油酸酯,采用层析柱对其进行提纯,采用红外光谱和质谱对其进行了定性分析。通过单因素考察,优化了目标产物的合成工艺条件。采用高频往复摩擦试验机评价其抗磨效果。结果表明:合成季戊四醇四油酸酯的工艺条件为:反应时间为1.5 h,反应温度为170℃,油酸、季戊四醇摩尔比为4.3∶1,催化剂用量为酸醇总质量的1.5%,在该工艺条件下季戊四醇四油酸酯的酯化率达到97.8%;合成的季戊四醇四油酸酯具有较高的运动粘度,粘度指数为219,酸值为0.37 mg KOH/g;季戊四醇四油酸酯大幅提高了柴油的抗磨性。 相似文献
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分别以硼酸、二乙醇胺、三氯氧磷和季戊四醇为原料,经酯化反应制得中间体二乙醇胺硼酸酯(DEAB, 1)和双季戊四醇二氯磷酸酯(SPDPC, 2); 1与2经缩聚反应合成新型集磷、氮、硼于一体的阻燃剂聚季戊四醇双磷酸酯二磷酰氯螺环二乙醇胺硼酸酯(PPSPSDB, 3),其结构经1H NMR, 13C NMR和FT-IR表征。考察了溶剂、物料比γ[n(2):n(1)]、反应温度和反应时间对3产率的影响,结果表明:在最佳反应条件(DMF为溶剂,γ=1 :1.2, 于120 ℃反应2 h后,于190 ℃反应2 h)下,产率93.26%。热重分析表明:3的初始分解温度为240.5 ℃, 800 ℃时残炭率为44.45%。 相似文献
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《有机化学》2016,(5)
以价格低廉的苯并噻唑为原料,合成了4种新型功能化布朗斯特酸性离子液体:苯并噻唑硫酸氢盐([HBth]-HSO_4)、苯并噻唑磷酸二氢盐([HBth]H_2PO_4)、苯并噻唑高氯酸盐([HBth]ClO_4)、苯并噻唑硝酸盐([HBth]NO_3),其结构经FT-IR、HRMS、NMR表征得到确认.考察了4种酸性离子液体在蓖麻油酸和乙二醇丁醚(EGBE)酯化反应中的催化活性,并与以浓硫酸为催化剂的催化体系相对照.结果表明:当n(蓖麻油酸)∶n(乙二醇丁醚)=1∶1.15,离子液体催化剂用量为蓖麻油酸重量的2%,反应温度90℃,反应时间5 h,酯化率可达98.8%,离子液体催化剂经真空干燥重复使用10次后,仍具有较高的催化活性.还考察了以苯并噻唑硫酸氢盐为催化剂催化合成系列蓖麻油酸二元醇醚酯和短链脂肪酸酯,也获得了较高的酯化率,且离子液体均能与酯产物自动分相.与传统硫酸催化酯化相比,此类离子液体催化酯化具有生产成本低、过程清洁、使用周期长等优点,完全可以替代传统浓硫酸催化蓖麻油酸酯化反应. 相似文献
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通过维生素E(VE)和辛烯基琥珀酸酐(OSA)的酯化反应,合成了维生素E辛烯基琥珀酸酯(VE-OS酯)。采用红外光谱(IR)和核磁共振波谱(NMR)对VE-OS酯的结构进行鉴定。研究发现,酯化反应后VE-OS酯的IR谱图中新增了1 860、1 776、1 755 cm-1的吸收峰,表明存在羧酸酯的结构;1H NMR谱中羟基信号消失,表明VE的羟基被取代;由于VE-OS酯存在a和b两个异构体,导致H-9的信号分布在3.05ppm和3.20 ppm,C-11和C-12在170~180 ppm处有4个峰,经比较积分面积认定a异构体更易生成。利用密度泛函理论(DFT)B3LYP/6-311++g**方法对VE-OS酯进行构型优化并确定a为较优构型,与实验分析完全一致。文中还采用HPLC方法对酯化反应进行了定量分析。 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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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
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A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL. 相似文献
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A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions. 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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Uroš Grošelj Mojca Žorž Amalija Golobič Branko Stanovnik Jurij Svete 《Tetrahedron》2013,69(52):11092-11108
A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives. 相似文献
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The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp3)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp2)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp2)?H and aliphatic 1,5- and 1,6-C(sp3)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp3)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp2)?H insertion. 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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Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular SN2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively. 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