共查询到19条相似文献,搜索用时 100 毫秒
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压力和温度对4-甲基二苯并噻吩和二苯并噻吩加氢脱硫反应的影响 总被引:1,自引:3,他引:1
研究了4-甲基二苯并噻吩(4-MDBT)和二苯并噻吩(DBT)在CoMo/γ-Al2O3上的加氢脱硫反应产物分布及其可能的反应网络,通过反应压力和温度对产物分布影响的研究,揭示了加氢脱硫反应的可能机理。研究发现4-MDBT在CoMo/γ-Al2O3上的加氢脱硫反应主要通过直接氢解路径和加氢路径进行,且两者反应速率相当;DBT在 CoMo/γ-Al2O3上的加氢脱硫反应主要通过直接氢解路径进行。4-MDBT分子位于4位的甲基阻碍其在催化剂表面通过硫原子的端连吸附,从而降低了其直接氢解脱硫路径的反应速率,因而也降低了其总的加氢脱硫转化率。反应压力降低,DBT和4-MDBT加氢脱硫反应中加氢路径反应速率明显下降,而其对氢解路径影响较小,但效果却与加氢路径相反,反应压力对4-MDBT转化率的影响大于DBT。反应温度对DBT和4-MDBT加氢脱硫反应中加氢路径和氢解路径都有明显影响,但是对DBT加氢脱硫反应中氢解路径的影响小于加氢路径,而对4-MDBT加氢脱硫反应中氢解路径的影响稍高于加氢路径,4-MDBT分子中甲基的供电子作用有利于相连苯环的加氢反应。 相似文献
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1991年发展起来的层层自组装(SA)是一种继Langmuir-Blodgett(LB)制膜技术之后的又一种以分子级控制的制备超薄膜的方法。虽然SA方法比LB膜技术晚了半个多世纪,但由于方法简单,不需专用设备;通常在水溶液中进行,对环境友好;对承受膜的物件形状和基材无严格限制等优点,十多年来一直受到关注,SA膜虽比LB膜稳定,但其层层间的离子键或氢键,仍不足以经受极性溶剂等的浸蚀,使其应用受到很大限制。 相似文献
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将缺电子单元-S,S-二氧-二苯并噻吩(SO)以2,8位引入到聚螺芴(PSFs)的主链,通过Suzuki聚合得到一系列具有不同SO含量的共聚物PSF-28SO-3、PSF-28SO-5、PSF-28SO-7和PSF-28SO-10。 不同于3,7位连接,该系列2,8-位连接的共聚物既有来自于高分子主链的本征态(LE:local excited)发光,又有来自于从四烷氧基芴侧链到主链中SO单元的电荷转移(CT:charge transfer)发光,最终表现为近白光发射。 其中,PSF-28SO-10具有最优器件性能,发光效率为0.58 cd/A,色坐标为(0.25,0.36)。 相似文献
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2-苯基苯并噻吩是一类重要的化合物,广泛应用于医药、农药和半导体等功能性材料的合成。 因此,其合成受到人们广泛关注,合成新方法不断出现。 本文从不同反应底物类别出发,对2-苯基苯并噻吩的合成方法进行了简要的综述和评价。 相似文献
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综述了螺烯的制备方法方面的进展,述及的螺烯制备方法包括光化学反应、Diels-Alder反应、成烯关环反应以及过渡金属催化三炔的[2+2+2]环化异构化反应等.此外,文中还对螺烯的手性拆分方法进行了论述,并对双螺烯的制备设计予以展望. 相似文献
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As the strongest triple bond in nature, the N≡N triple bond activation has always been a challenging project in chemistry. On the other hand, since the award of the Nobel Prize in Chemistry in 1950, the Diels-Alder reaction has served as a powerful and widely applied tool in the synthesis of natural products and new materials. However, the application of the Diels-Alder reaction to dinitrogen activation remains less developed. Here we first demonstrate that a transition-metal-involved [4+2] Diels-Alder cycloaddition reaction could be used to activate dinitrogen without an additional reductant by density functional theory calculations. Further study reveals that such a dinitrogen activation by 1-metalla-1,3-dienes screened out from a series of transition metal complexes (38 species) according to the effects of metal center, ligand, and substituents can become favorable both thermodynamically (with an exergonicity of 28.2 kcal mol−1) and kinetically (with an activation energy as low as 13.8 kcal mol−1). Our findings highlight an important application of the Diels-Alder reaction in dinitrogen activation, inviting experimental chemists’ verification. 相似文献
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The title hydrocarbon 3, a C14H14 tetracyclic tetraene of C2v-symmetry, was synthesized by new routes starting from 1,8,9,10-tetrachloro-11,11-dimethoxytricyclo[6.2.1.02,7]undeca-3,5,9-triene (1). The Diels-Alder cycloaddition of 1 with 2-chloroacrylyl chloride, a ketene equivalent, followed by subsequent reduction, dechlorination and deacctalization afforded the ketol 12 as a key intermediate. Elaboration of target compound 3 was carried out by either the method of ring enlargement of 12 or (better) the route of Diels-Alder reaction of decarbonylated 12 with trans-1,2-bis(phenylsulfonyl)ethcnc, an acetylene equivalent, to give trienol 17, followed by dehydration. Upon irradiation, 3 underwent intercyclic [2 + 2]-addition to caged hexacyclic diene 4. At 120°C, 3 decomposed into barrelene and benzene quantitatively. 相似文献
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合成文拉法星的2-氮杂-1,3-丁二烯杂Diels-Alder反应与其 单分子环合竞争反应的研究 总被引:1,自引:0,他引:1
研究了不同的Lewis酸催化剂、温度、微波等条件下, 4-(4-甲氧苯基)-1-苯基-3-三甲基硅氧基-2-氮杂-1,3-丁二烯(2-ABDE)和亲二烯体环己酮发生杂Diels-Alder反应生成[4+2]的六元环合产物噁嗪酮衍生物, 伴随的2-ABDE的 [2+2]单分子环合, 生成单环β-内酰胺衍生物. 结果表明: 在低温条件下如(-78 ℃)[4+2]反应占主导; 而在高温条件下(如135 ℃)仅进行[2+2]反应. 微波加热方式可显著提高[2+2]反应的速率和产率. 不同的Lewis酸催化剂对[2+2]反应和[4+2]反应的催化效率不同. Lewis酸的酸性强弱、软硬对2-ABDE的[2+2]反应的催化能力起决定性作用. 相似文献
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《中国化学》2018,36(4):273-279
o‐Carboryne (1,2‐dehydro‐o‐carborane) is a very useful synthon for the synthesis of a variety of carborane‐functionalized molecules. Diels‐Alder reaction of o‐carboryne with furans gave a series of carborane‐fused oxanorbornenes in moderate to high yields using 1‐OTf‐1,2‐C2B10H11 as carboryne precursor. The resultant cycloadducts can undergo hydrogenation, cyclic oxidation, bromination, [4 + 2]/[2 + 2] cycloaddition and nucleophilic ring opening reaction to afford a variety of highly functionalized carboranes that may find applications as useful basic units in medicine and materials science. 相似文献
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Yuriy I. Horak Roman Z. Lytvyn Yevhen-Oleh V. Laba Yuriy V. Homza Vladimir P. Zaytsev Maryana A. Nadirova Tatiana V. Nikanorova Fedor I. Zubkov Alexey V. Varlamov Mykola D. Obushak 《Tetrahedron letters》2017,58(43):4103-4106
The reaction of readily accessible 3-(thien-2-yl)allylamines with maleic anhydride, followed by a domino sequence involving successive acylation/[4+2] cycloaddition steps, leads to the formation of the thieno[2,3-f]isoindole core. The key step, the intramolecular Diels-Alder vinylaren (IMDAV) reaction, proceeds with high level of diastereoselectivity and with formation of a single diastereoisomer of the target product 4,4a,5,6,7,7a-hexahydro-3aH-thieno[2,3-f]isoindole-4-carboxylic acids in excellent yields. If the reaction is carried out at room temperature, it occurs in 2–3 days and the proton migration (H-shift) does not take place at the last stage. In boiling benzene, the reaction is complete after three hours, but in this case a slight impurity of byproducts bearing aromatic thiophene ring – 4a,5,6,7,7a,8-hexahydro-4H-thieno[2,3-f]isoindole-4-carboxylic acids is formed. 相似文献
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Meng‐Yang Chang Bo‐Rm Chang Chung‐Ho Chang Shui‐Tein Chen Nein‐Chen Chang 《中国化学会会志》2002,49(2):233-237
A formal synthesis of (±)‐isodihydronepetalactone ( 1 ) from cyclobutenone 5 was de scribed. Baeyer‐Villiger lactonization of cyclobutanone 8 followed by decholorination led to lactone 4 , which under went a series of functional group trans formations, furnished cyclopentanone derivative 15 . Shapiro reaction on hydrazone derivative in the presence of excess dry ice gave lactone 2 . Lactone 2 had previously been converted to isodihydronepetalactone ( 1 ). 相似文献
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D. D. Nekrasov 《Chemistry of Heterocyclic Compounds》2001,37(8):925-938
Methods for the production of 6-aryl-2,2-dimethyl-1,3-dioxin-4-ones and their thermolysis in the presence of nucleophiles and dienophiles are discussed 相似文献