共查询到20条相似文献,搜索用时 78 毫秒
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在B3LYP/6-31G*水平上以二甲醚(Me2O)模拟四氢呋喃(THF)对烯烃在THF溶液中硼氢化反应的机理进行了研究.计算结果发现,烯烃通过类似SN2的交换过程从醚与BH3构成的配合物获得BH3结合成π配合物中间体,这一交换是整个硼氢化反应的决速步骤. 相似文献
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烯烃的Friedel-Crafts烷基化反应(以下简称F-C烷基化反应)一般采用金属卤化物和浓硫酸作催化剂,但两种情况下的后处理都比较复杂,要消耗大量溶剂,催化剂只能一次性使用。近年来,由于苯乙烯与二甲苯反应产物为具有多种工业用途的材料"PXE",国内外相继报道使用不同的催化剂来改进该反应,这些反应各有优点,但均未提及机理和与之竞 相似文献
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巴豆醛在过量乙硼氢的硼氢化反应中得到的主要产物是正丁醇。本文论证这一反应的历程,其中包括有“二硼酸”型的β-消除反应。还讨论有电负性元素取代的烯烃的硼氢化反应。巴豆醛在低温(-25°)硼氢化,可使这类消除反应大为减少,主要得到硼氢化的正常产物——丁二醇。 相似文献
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In the presence of a catalytic amount of BH3·Me2S, TiCl4 or Me3SiCl, LiBH4 or NaBH4 are capable of hydroborating alkenes by following the unusual order of decreasing reactivity: tetramethylethylene > 1-methylcyclohexene > cyclohexene; the key step of the catalytic cycle is the exchange reaction between LiBH4 and the mono- or dialkylboranes resulting from hydroboration of the more substituted alkenes with BH3. 相似文献
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《Green Chemistry Letters and Reviews》2013,6(4):213-216
Abstract Aromatic aldehydes having hydroxyl substituent(s) react with urea (or thiourea), and ethyl acetoacetate (or acetylacetone) in the presence of p-toluenesulfonic acid as catalyst and water as solvent to give substituted dihydropyrimidinones (Biginelli compounds) in good to excellent yields. 相似文献
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A new functionalization of indoles via palladium-catalyzed reaction of indoles and 2-acetoxymethyl substituted electron-deficient alkenes is reported. The reaction was carried out under neutral condition and no isomerization of the carbon-carbon double bond was observed. 相似文献
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I. A. Nuretdinov I. P. Karaseva V. P. Gubskaya A. V. Il'yasov 《Russian Chemical Bulletin》1995,44(8):1486-1488
Cycloaddition of substituted 6,6-dimethyl-2-vinylnorpinenes with maleic anhydride occursvia the attack of a dienophile on diene from the less hindered side of the bicyclic fragment. IR, UV, CD, and1H NMR spectra of adducts have been studied.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1546–1548, August, 1995.The authors are grateful to I. E. Ismaev for recording several1H NMR spectra. 相似文献
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Y. Paul Handa Jacques Roovers Pierre Moulini 《Journal of Polymer Science.Polymer Physics》1997,35(14):2355-2362
Tert-butyl and di-tert-butyl were added as pendant groups to the ether-ether phenyl ring of poly(ether ether ketone), PEEK. tert-butyl PEEK, TBPEEK, was amorphous and di-tert-butyl PEEK, DBPEEK, was semicrystalline. However, a 2 : 1 random copolymer of TBPEEK and DBPEEK, TBDBPEEK, was amorphous. Gas transport of N2, O2, CH4, and CO2 through amorphous films of PEEK, TBPEEK, TBDBPEEK, and tetramethylbiphenyl PEEK were determined at 35°C and at pressures to about 15 atm. The results support previous observations that tert-butyl and tetramethylbiphenyl groups are very effective in disrupting chain packing in the polymer. For the present polymers, these substitutions led to a 5–18-fold increase in permeability, and, in some cases, at no loss in permselectivity. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 2355–2362, 1997 相似文献
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Air‐stable symmetric Schiff base have been synthesized and proved to be efficient ligands for Suzuki–Miyaura reaction between aryl bromides and arylboronic acids using PdCl2(CH3CN)2 as palladium source under aerobic conditions. The coupling reaction proceeded smoothly using N,N‐bis(anthracen‐9‐ylmethylene)benzene‐1,2‐diamine (L7) as ligand to provide 4‐substituted styrene compounds in good yields. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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《应用有机金属化学》2017,31(6)
A new method has been developed for the preparation of substituted pyrrolidines by the palladium‐catalyzed intramolecular bromoamination of substituted aminoalkenes. The catalytic system and reaction conditions used for this transformation have been fully optimized. Notably, this reaction exhibits excellent selectivity, affording the pyrrolidine products as single 5‐exo‐bromoalkylpyrrolidines in excellent yields. Furthermore, this reaction occurs at room temperature under mild conditions, reaching completion within 1 h. 相似文献