硫脲基咪唑啉季铵盐的合成及其缓蚀作用

用戊酸、羊蜡酸、油酸、二乙烯三胺、氯化苄和硫脲为原料,合成了6种咪唑啉季铵盐化合物。 采用静态失重法和极化曲线法,比较了硫脲基烷基咪唑啉型季铵盐和烷基咪唑啉型季铵盐在80 ℃、1 mol/L的HCl溶液中对碳钢的缓蚀性能,研究了这两类缓蚀剂与无机阴离子和阴离子表面活性剂的协同作用。 结果表明,硫脲基烷基咪唑啉季铵盐类的缓蚀效果明显优于烷基咪唑啉季铵盐类,硫脲基羊脂酸咪唑啉缓蚀剂的缓蚀率可达98.3%。 当以羊脂酸、二乙烯三胺、氯化苄和硫脲为原料合成的硫脲基烷基咪唑啉型季铵盐化合物与I-质量比为1∶1复配时,缓蚀效果最佳,比单独使用硫脲基烷基咪唑啉季铵盐化合物的缓蚀率提高了1.5%。     

分子结构对咪唑啉缓蚀剂膜在Q235钢表面生长和衰减规律的影响

采用弱极化法、电化学阻抗谱等手段研究了烷基咪唑啉和硫脲基烷基咪唑啉缓蚀剂对Q235钢在饱和CO2盐溶液中的缓蚀行为变化, 探讨了吸附膜的形成与衰减规律. 结果表明, 烷基咪唑啉和硫脲基烷基咪唑啉缓蚀剂都是以控制阳极过程为主的混合界面型缓蚀剂. 在85 ℃下, 烷基咪唑啉成膜相对较慢, 吸附能力较弱, 容易发生脱附; 而硫脲基的引入, 使得硫脲基烷基咪唑啉缓蚀剂溶液存在自动修复能力, 增强了咪唑啉环的吸附性能, 提高了缓蚀剂的缓蚀性能; 硫脲基烷基咪唑啉水解开环后, 成膜性能下降, 膜寿命和缓蚀效率也大大降低. 最后采用量子化学计算对上述结论进行了验证和解释.     

新型咪唑啉缓蚀剂的合成与应用

采用苯甲酸、月桂酸、二乙烯三胺和三乙烯四胺为原料,合成了4种咪唑啉季铵盐缓蚀剂,研究了在50℃、体积分数为5%的HCl介质中,咪唑啉季铵盐与阴离子表面活性剂和无机阴离子的协同作用.结果表明,以月桂酸和三乙烯四胺为原料合成的咪唑啉季铵盐与I-质量比为1:1时,缓蚀效果最佳.在不同时间和不同温度下对复合型缓蚀剂的缓蚀率的研究结果表明,缓蚀剂在静态条件下对A3钢的缓蚀率可达99.4%.较之单独使用咪唑啉季铵盐提高了1.1%左右.     

2种癸二酸咪唑啉季铵盐的合成及缓蚀性能评价

合成了2种癸二酸咪唑啉季铵盐癸二酸-水杨酸咪唑啉季铵盐(SSAI)和癸二酸咪唑啉季铵盐(SAI),并采用失重法和电化学方法研究了这2种咪唑啉季铵盐对N80钢在1 mol/L HCl溶液中的缓蚀性能和吸附行为。 结果表明,在1 mol/L HCl溶液中这2种化合物对N80钢均有较好的缓蚀作用,缓蚀效率大小顺序为SSAI＞SAI。 SSAI和SAI均为混合偏阳极型缓蚀剂。 2种化合物在N80钢表面的吸附服从Langmuir吸附等温式,属于化学吸附。     

改性咪唑啉类缓蚀剂缓蚀机理的分子模拟

基于密度泛函理论和分子动力学分别研究了油酸咪唑啉(C17)、季铵化改性咪唑啉(QI)和环氧乙烷改性咪唑啉(EOI)的反应活性、吸附方式、吸附强度和最优吸附构型,揭示了 3种缓蚀剂的缓蚀机理.结果表明:3种缓蚀剂分子的反应活性区域主要分布在咪唑环、头基的N原子以及苯环上;3种缓蚀剂分子的缓蚀能力大小为QI＞EOI＞C17...     

咪唑啉衍生物缓蚀剂对碳钢在CO2盐水中的缓蚀机理

采用极化曲线和交流阻抗研究新合成咪唑啉衍生物缓蚀剂对碳钢在饱和CO2盐水中的缓蚀性能和机理. 计算了缓蚀效率和热力学参数. 缓蚀效率随着缓蚀剂浓度增大而增加, 但随着温度增加先增加后降低. 咪唑啉衍生物在碳钢表面的吸附符合Langmuir等温式. 电化学结论由量子化学计算补充说明.     

流动条件下两种不同亲水基团咪唑啉型缓蚀剂的缓蚀性能

选择了两种含有不同亲水基团的咪唑啉型缓蚀剂, 即1-胺乙基-2-十一烷基咪唑啉(AEI-11)和1-羟乙基-2-十一烷基咪唑啉(HEI-11), 分别在静态及动态条件下,采用失重法、极化曲线法、电化学阻抗谱法研究了上述缓蚀剂对N80钢在CO2饱和的3%(w)NaCl溶液中的缓蚀性能. 研究结果表明, 无论在静态和动态条件下, HEI-11均表现出更佳的缓蚀性能, 即咪唑啉型缓蚀剂的缓蚀性能与亲水基团的极性成正比; 在流动条件为5 m·s-1时, 缓蚀剂的缓蚀效率显著降低. 为了进一步研究缓蚀剂的缓蚀性能与其结构的关系, 运用量子化学法计算了缓蚀剂的EHOMO(最高占有分子轨道)、ELUMO(最低空分子轨道), 结果表明缓蚀剂的缓蚀效率与EHOMO成正比, 与ELUMO及ELUMO与EHOMO的差值驻E成反比.     

羟基取代菲并咪唑衍生物对低碳钢的缓蚀性能

通过分子设计,增大邻菲罗啉平面结构,在不同位次引入-OH,合成2-(2-羟基苯基)-1H-咪唑[4,5-f][1,10]邻菲啰啉(2HIP)、2-(3-羟基苯基)-1H-咪唑[4,5-f][1,10]邻菲啰啉(3HIP)和2-(4-羟基苯基)-1H-咪唑[4,5-f][1,10]邻菲啰啉(4HIP)等三种羟基取代菲并咪唑衍生物。采用失重法、电化学法以及扫描电镜等研究其在1mol·L^-1HCl溶液中对低碳钢的缓蚀性能。三种缓蚀剂在低碳钢表面服从Langmuir吸附,缓蚀效率在实验浓度范围内均超过了90%,且4HIP具有最好的缓蚀效果,最高缓蚀效率为96.36%。DFT理论计算探讨了三种缓蚀剂分子结构与缓蚀剂效率关系,理论计算与实验结果具有一致性。     

1－硫脲乙基－2－芳基－2－咪唑啉化合物的合成

１－硫脲乙基－２－芳基－２－咪唑啉化合物的合成刘运廷，章荣玲（山东工业大学数理系济南，２５００１４）关键词咪唑啉，硫脲基，芳基，合成咪唑啉衍生物由于具有缓蚀、杀菌、抗癌等活性而迅速发展￣［１，５］。作者曾研究过各种咪唑啉衍生物的合成￣［６］，系采用通...     

取代基咪唑啉与铁原子化学吸附作用能的量子化学计算

用量子化学方法计算了６个咪唑啉型化合物及其与铁原子的化学吸附作用能,探讨了这种作用能与缓蚀性能的关系。得到咪唑啉环上氮与铁的配位键长、双原子作用能以及重叠集居数。研究发现具有ｐ－π共轭体系的咪唑啉以及在环上引入供电子基团或取代芳烃,能增强氮与铁原子的化学吸附作用力。计算结果可为设计性能较好的新型咪唑啉缓蚀剂提供有用的信息。     

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.