阴极冷却反应器电合成乙醛酸

以过饱和草酸水深液为阴极液 ,盐酸溶液为阳极液 ,在阴极冷却电化学反应器内草酸电解合成乙醛酸 .考察了电极温度、电解液温度、电流密度和电极材料对合成乙醛酸的时空产率和电流效率的影响 .结果表明 ,阴极冷却反应器既节省能耗 ,又可使电解过程在较高草酸浓度下进行 ,提高电流效率和时空产率 .用石墨板做阳极 ,铅做阴极 ,电流密度为 4 0 9.4 6A·m-2 ,阴极液流速 μ=1 .0 8m·s-1,电解温度为 2 0℃左右时 ,电解 3 .70h ,可得到质量分数为 3 .52 %的乙醛酸溶液 ,平均时空产率为 0 .0 3 2kg·dm-3·h     

离子交换膜法合成2,2′-二氯氢化偶氮苯

应用离子交换膜法电解邻氯硝基苯合成2,2′-二氯氢化偶氮苯.讨论了电极活化条件、电流密度、电解液温度等因素对电解还原反应的影响.结果表明:在反应温度t=80℃,阴极、阳极电解液分别为10%和30%(by m ass)的NaOH溶液,电流密度4.2A/dm2条件下电解,电流效率最高,可达73%,收率为83%.     

固定床反应器电合成乙醛酸的研究

以过饱和草酸水溶液为阴极液 ,盐酸为阳极液 ,在固定床电解槽中草酸电还原得到乙醛酸 .考察改变固定床的结构、电解温度及电流密度对生成乙醛酸电流效率和产率的影响 .结果表明 ,以铅粒作阴极 ,石墨板作阳极 ,电流密度 96 .3A·m- 2 ,阴极液空速 0 .5 0 5m·s- 1,电解温度 32℃时 ,在固定床双阳极室内反应 4 5min ,乙醛酸的电流效率仍达到 6 6 .2 % ,浓度 2 .0 2 %     

电化学羧化苯乙烯合成2-苯基丁二酸

在常压CO₂气氛下，含0.1 mol·L^-1 TEABr的MeCN溶液中，以Ti为阴极，Mg棒为阳极电羧化苯乙烯能有效地合成2-苯基丁二酸。研究了电极材料、电流密度、通电量和反应温度对电解的影响，在最优条件下的分离产率最高可达86.07%。并通过循环伏安行为研究电羧化过程的机理。     

以糠醛为原料的成对电合成

研究了Ti/Ru-Ti-Sn,Ni,Ti/PbO_2,Pt和Ti/BDD(钛基掺硼金刚石电极)5种电极的析氧情况及对糠醛电化学氧化成糠酸的催化作用,得出氧化的最佳电极为Ni.以糠醛为原料,Ni电极为阳极,Cu电极为阴极,成对电合成糠醇和糠酸,研究了溶液p H值、电流密度、糠醛浓度、温度及电解时间对反应的影响.结果表明,溶液pH=11,阴极电流密度为2 mA/cm~2,阳极电流密度为1 mA/cm~2,糠醛浓度为0.1 mol/L,温度为25℃时,经过优化,总的电流效率最佳为130%.     

熔盐电解LiCl-KCl-AlCl3-La2O3共析出制备Al-Li-La合金

研究了LiCl-KCl-AlCl3-La2O3熔盐体系中共析出制备Al-Li-La合金的可行性。研究表明,在LiCl-KCl熔盐中,AlCl3将La2O3氯化为LaCl3,使电解制备Al-Li-La合金顺利进行。借助循环伏安法对熔盐体系的电化学行为进行分析发现,对质量比为45∶45∶5∶2的LiCl-KCl-AlCl3-La2O3熔盐,当阴极电流密度大于0.25 A/cm2,可以实现Al、Li和La的共析出。通过研究电解温度、阴极电流密度和电解时间对合金组成的影响,得到了较佳的电解参数:电解温度650℃,在LiCl-KCl混合熔盐中加入质量分数为5%的AlCl3和2%的La2O3,阴极电流密度12.5 A/cm2,电解时间1 h。X射线衍射对合金分析测试表明,合金主要由Al2La和βLi组成。     

电解还原法合成间苯二胺

在酸性介质中以铜为阴极、石墨为阳极电解还原间二硝基苯制备间苯二胺。考查了温度、电流密度、间二硝基苯用量和盐酸质量百分数对间苯二胺产率的影响及电量对电流效率的影响 ,正交实验确定反应的最佳条件为 :温度 4 0℃ ,电流密度 4A·dm- 2 ,间二硝基苯 0 .2 5g ,HCl质量百分数 15 %。在最佳条件下 ,间苯二胺的产率达 74 .2 %。     

温和条件下电活化co2合成碳酸二甲酯

在含0.1mol/L四乙基铵四氟硼酸盐的乙腈和N,N-二甲基甲酰胺溶液中,研究了CO2在铜电极上的循环伏安行为。结果表明,CO2在电位E=-2.3V(vs.Ag/AgI)发生不可逆还原。在常压CO2气气氛下,含0.1mol/L四乙基铵四氟硼酸盐的乙腈溶液的一室型电解池中,以镁为牺牲阳极,铜为工作电极,Ag/AgI电极为参比电极,在一定电位下电解时,CO2可以被电活化并与甲醇反应,加入烷基化试剂碘甲烷后可得碳酸二甲酯(DMC)。该合成方法安全清洁、体系简单、实验条件温和。考察了电解电位、通电量、反应温度、支持电解质、溶剂、电极材料等对电解产率的影响。确定当E=-2.3V(vs.Ag/AgI),通电量为理论电量,以四乙基铵四氟硼酸盐为支持电解质,乙腈为溶剂,在25℃和常压下反应,DMC产率最高,为14.92%。表明以CO2和甲醇为原料在温和条件下(PCO2=1.0atm,T=25℃)电合成制备DMC具有一定的可行性。     

稀土贮氢合金电极在乙醛酸电解制备中的应用

研究了以AB5型稀土贮氢合金作催化还原电极恒电位电解草酸制备乙醛酸,合金表面处理和电极活化可提高电解产率和电流效率.确定了最佳电解工艺条件:电流密度120mA·dm-2,电解液温度30℃,草酸浓度1.0mol·L-1,此时电流效率为86%,电解产率为88%.随着电解次数的增加,由于贮氢合金膨胀粉化及表面被电解产物覆盖,电流效率和乙醛酸产率均呈下降趋势,在电解过程中即时分离电解产物有利于提高电流效率和乙醛酸产率.     

电沉积Ni/LaNiO3复合电极及其在碱性介质中的析氧性能

采用溶胶-凝胶法制备了钙钛矿型复合氧化物LaNiO3,然后将其加入瓦特镀镍液中进行复合电沉积,研究了镀液pH值和阴极电流密度对Ni/LaNiO3复合镀层组成的影响。运用扫描电镜(SEM)、能谱分析(EDS)和X射线衍射(XRD)等对复合镀层进行表征,结果表明:最佳电沉积工艺条件是镀液pH=5.8和阴极电流密度jk=90 mA.cm-2,所得的Ni/LaNiO3复合镀层中LaNiO3的质量含量约为60%。用循环伏安、稳态极化、恒电位阶跃、电化学阻抗谱等电化学技术评价了Ni/LaNiO3复合电极的析氧性能。结果表明:在5 mol.L-1的KOH溶液中,Ni/LaNiO3复合电极的起始析氧电位较镍电极负,表观活化自由能比镍电极降低约2/3,比表面积约为镍电极的55倍,析氧电催化性能得到大幅度提高。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

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%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

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.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

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.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

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.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

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.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

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.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

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.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

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.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

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.