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1.
氢氧化锂存在下(焦)脱镁叶绿酸-a甲酯的空气重排反应 总被引:1,自引:0,他引:1
在氢氧化锂存在下, 脱镁叶绿酸-a甲酯(1a)发生空气氧化和重排反应, 经盐酸酸化和重氮甲烷甲基化, 得到由紫红素-7三甲酯(2)、紫红素-18甲酯(3)、卟吩-p6三甲酯(4)、地质卟啉衍生物(5)和3-环氧乙基-3-去乙烯基紫红素-18甲酯(6)所组成的混合物. 用相同的方法处理焦脱镁叶绿酸-a甲酯(1b), 则分离出132-氧代焦脱镁叶绿酸-a甲酯(7)、15-甲酰基紫红素-5二甲酯(8)、紫红素-18甲酯(3)和3-环氧乙基-3-去乙烯基紫红素-18甲酯(6). 所得新叶绿素衍生物5, 6和8的化学结构均经UV, IR, 1H NMR及元素分析得以证实, 并对相应的反应提出可能的反应机理. 相似文献
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M. V. Simonova E. G. Zhizhina V. V. Russkikh K. I. Matveev 《Russian Chemical Bulletin》2005,54(6):1532-1534
Mo—V-phosphoric heteropolyacids (HPA) can be used for aniline oxidation to polyaniline or 1,4-benzoquinone. At room temperature
and the molar ratio HPA : aniline = 0.67, more than 95% substrate are oxidized to polyaniline. At 90–100 °C and HPA : aniline
= 3, the substrate is quantitatively oxidized to 1,4-benzoquinone. Solutions of HPA are regenerated by oxygen in a separate
step.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1488–1490, June, 2005. 相似文献
3.
在无任何外加溶剂及共还原剂的条件下, 将金属次卟啉二甲酯应用于催化空气氧化环己烷的氧化反应. 结果表明, 金属次卟啉二甲酯能够很好地催化环己烷的氧化反应, 与简单的金属四苯基卟啉相比, 金属次卟啉二甲酯催化剂具有更高的催化活性. 进而研究了络合金属对其催化性能的影响. 相似文献
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A practical copper-catalyzed aerobic oxidation for the amination of benzoxazole with secondary amine has been discovered. This reaction has proved to be effective to a variety of amines with lower catalyst loading amount, and only oxygen in air is required to facilitate this transformation. A copper-catalyzed/amine-induced ring opening of the benzoxazole and recyclization mechanism was also proposed. 相似文献
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L. N. Novikova I. V. Shchirina-Eingorn N. A. Ustynyuk P. V. Petrovskii L. I. Denisovich 《Russian Chemical Bulletin》1997,46(5):1007-1009
Oxidation of the cyclohexadienyl complex Fe(η5-C5H5)(1-5-75-6-exo-C5H5-C6H6) (2) by (Ph3C)PF6 (CH2Cl2, from −30 to +20 °C) occurs as two concurrent processes: elimination of an H atom from the cyclohexadienyl ligand and replacement
of an H atom in the cyclopentadienyl ring by a CPh3 fragment. A mixture of cationic complexes [Fe(η5-C5H5) (η6-Ph-C5H5]+ (1+) and [Fe(η5-C5H4CPh3) (η6-Ph-C5H5]+ (4+) (4
+) with PF6
− anions is obtained. Deprotonation of the mixture of 1+ and 4+ complexes under the action of Bu
t
OK inm-xylene followed by boiling of the reaction mixture gives phenylferrocene (7) as the product of η6:η6 haptotropic rearrangement.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, NO. 5, pp. 1045–1047, May, 1997. 相似文献
8.
A series of iron(Ⅲ) chlorophyllins was prepared from silkworm excrement crude chlorophyll extract as a raw material. Aerobic oxidation of cyclohexene by using the prepared iron(Ⅲ) chlorophyllins as biomimetic catalysts was studied under atmospheric pressure in the absence of reducing agent and solvent. The results indicate that chlorophyll iron porphyrins have better catalytic performance than the industrial-applied iron tetraphenylporphyrin and cobalt tetraphenylporphyrin, and possess a higher selectivity for 2-cyclohexen-1-one. The smaller the polarity of iron(Ⅲ) chlorophyllin's ligand is, the easier the catalytic oxidation of cyclohexene will be. Esterification products of iron(Ⅲ) chlorophyllins can catalyze the oxidation of cyclohexene better than non-esterified iron(Ⅲ) chlorophyllins, and therefore show a higher conversion of cyclohexene and a higher selectivity for 2-cyclohexen-1-one than the non-esterified ones. Among the six synthesized iron(Ⅲ) chlorophyllin catalysts, iron(Ⅲ) methyl-pyropheophorbide-a is the best biomimetic catalyst for the highest conversion of cyclohexene. The influences of catalyst's substituent, polarity and ring structure on the catalytic performance were discussed. The catalytic performance of iron(Ⅲ) chlorophyllins improves with decreasing polarity, increasing conjugated degree of porphyrin's ring or enhancing chlorophyllins' stability. Possible mechanism of cyclohexene aerobic oxidation catalyzed by iron(Ⅲ) chlorophyllins was also discussed. 相似文献
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通过多组实验,探究硫化钠晶体在空气中的氧化产物,结论是单质硫、多硫化钠、亚硫酸钠、硫酸钠的混合物。 相似文献
10.
Dr. David Pierrot Prof. Dr. Ilan Marek 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(46):20614-20618
The preparation of acyclic molecules featuring congested stereocenters in a 1,4-relationship in only three catalytic steps from commercially available building blocks is reported. This approach involves a diastereoselective diboration of alkenyl cyclopropyl methanol derivatives followed by a regioselective exergonic ring fragmentation. The starting materials can be prepared enantiomerically enriched and all substituents can be interconverted, therefore, this strategy allows a large variety of diversely functionalized allylboronic esters possessing distant tetrasubstituted stereocenters with high diastereoselectivity. 相似文献
11.
金催化剂催化环己烷液相选择氧化研究 总被引:6,自引:0,他引:6
采用溶胶-凝胶法制备了一系列担载纳米金催化剂,用于催化环己烷液相选择氧化反应.在反应体系中没有加入任何溶剂或助催化剂,考察了反应温度、时间、压力和不同焙烧温度对催化剂活性的影响.实验结果表明,催化剂在250℃焙烧和金含量为0.032%时,环己烷选择氧化可以达到10.8%的转化率和90.8%的目的产物(环己醇和环己酮)选择性,相应转化频率高达5.2×104. 相似文献
12.
采用氧化还原法制备了MnOx催化剂,X射线衍射结果表明其主要为无定形结构.在甲醛和臭氧浓度分别为137和642mg/m3,相对湿度为56%(25oC),GHSV为2×105h-1条件下,MnOx催化剂上O3可将甲醛全部氧化为CO2,反应150min内甲醛转化率和CO2选择性一直保持在~100%.另外,当臭氧与甲醛的摩尔比约为2:3,即显著低于化学计量比时,CO2选择性仍可达~100%.采用傅里叶变换红外光谱仪在线分析了甲醛氧化反应产物,未检测到任何副产物,从而确认了MnOx催化剂上O3对甲醛的完全氧化. 相似文献
13.
One‐Pot Synthesis of O‐Allylhydroxylamines through the Organocatalytic Oxidation of Tertiary Allylic Amines Followed by a [2,3]‐Meisenheimer Rearrangement 下载免费PDF全文
Alexis Theodorou Dr. Dimitris Limnios Prof. Dr. Christoforos G. Kokotos 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(13):5238-5241
A cheap, green, and highly efficient one‐pot method for the synthesis of O‐protected allylic alcohols is described. By utilizing 2,2,2‐trifluoroacetophenone as the organocatalyst and H2O2 as the oxidant, a variety of allylic amine N‐oxides were synthesized, which upon heating are converted to the final products through a [2,3]‐Meisenheimer rearrangement. 相似文献
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Satoru Hiroto 《化学:亚洲杂志》2019,14(15):2514-2523
In this review, we focus on the synthesis of π‐conjugated functional molecules by the oxidation of aromatic amines, which is one of the most effective methods for the construction of C?C, C?N, and N?N bonds between two π‐conjugated molecular units, and consider their characteristics and applications. Polyanilines are the most common products of the oxidation of aromatic amines; however, azobenzenes, phenazines, and 1,1′‐binaphthyl‐2,2′‐diamines may be produced in this manner also, depending on the reaction conditions. Recent advances in the methodology of aniline oxidation have led to the development of high‐regioselectivity industrial‐scale syntheses of optically or electroactive π‐functional dyes containing nitrogen atoms. In particular, the regioselective fusion of π‐extended aromatic amines can be used to prepare distorted π‐conjugated molecules under mild reaction conditions, allowing the construction of unprecedented curved nitrogen‐containing π‐conjugated molecules. 相似文献
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Milan Parchovianský Ivana Parchoviansk Peter van
rek David Medve Mateus Lenz-Leite Günter Motz Duan Galusek 《Molecules (Basel, Switzerland)》2021,26(8)
This work is aimed at the development and investigation of the oxidation behavior of ferritic stainless-steel grade AISI 441 and polymer-derived ceramic (PDC) protective coatings. Double-layer coatings of a PDC bond coat below a PDC top coat with glass and ceramic passive fillers’ oxidative resistance were studied at temperatures up to 1000 °C in a flow-through atmosphere of synthetic air and in air saturated with water vapor. Investigation of the oxide products formed at the surface of the samples in synthetic air and water vapor atmospheres, at different temperatures (900, 950, 1000 °C) and exposure times (24, 96 h) was carried out on both uncoated steel and steel coated with selected coatings by scanning electron microscopy (SEM) and X-Ray diffraction (XRD). The Fe, Cr2O3, TiO2, and spinel (Mn,Cr)3O4 phases were identified by XRD on oxidized steel substrates in both atmospheres. In the cases of the coated samples, m- ZrO2, c- ZrO2, YAG, and crystalline phases (Ba(AlSiO4)2–hexacelsian, celsian) were identified. Scratch tests performed on both coating compositions revealed strong adhesion after pyrolysis as well as after oxidation tests in both atmospheres. After testing in the water vapor atmosphere, Cr ions diffused through the bond coat, but no delamination of the coatings was observed. 相似文献
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咪唑修饰硅胶配位固载锰(Ⅲ)卟啉对环己烷空气氧化的催化作用 总被引:11,自引:0,他引:11
应用3-氯丙基三甲氧基硅烷和咪唑成功地对硅胶表面进行了修饰,并通过咪唑基纵轴配位方式固载了四苯基锰(Ⅲ)卟啉.在无任何外加溶剂及共还原剂的条件下,应用此高分子金属卟啉作为催化剂,选择性地催化空气氧化环己烷为环己酮和环己醇.研究结果表明,与未固载金属卟啉相比,固载金属卟啉具有更高的催化活性和催化选择性,反应具有更高的酮醇比,催化剂的稳定性有了较大的提高,便于回收和重复使用.另外还探讨了载体在此催化体系中对催化性能的影响. 相似文献