水溶液中Ni-La-P合金的电沉积行为

为了开发含稀土的功能材料,我们研究了从水溶液中电沉积Ni-La-P合金工艺[1].刘淑兰等[2]报道了电沉积的Ni-La合金上的阴极析氢行为,但未见Ni-La合金电沉积行为的报道.本文采用动电位扫描法,研究了电沉积Ni-La-P合金过程中,镀液中的配体、H3PO3和Ni2 离子的作用.采用动电位扫描法测量合金电沉积时的阴极极化曲线.所用仪器有DHW型恒电位仪（延边电化学仪器厂）,YEW-TYPE-3086型X-Y函数记录仪（四川仪表四厂）.电极：阴极为1cm2铜片,阳极为5cm2Pt片,参比电极：饱和甘汞电极（SCE）.实验溶液广：NiCl2·6H2O25g/L,NH4Cl9g/L,L1-…     

稀土在电沉积镍-钴合金中的作用

由于稀土元素具有独特的电子层结构和化学性能,使稀土及其化合物在材料科学领域中的应用越来越广泛,尤其是稀土在电沉积过程中的研究及应用正日趋深入。这是因为在电镀溶液中加入少量的稀土化合物后,可以改善镀液的分散能力和深镀能力,提高电镀的电流效率,增加镀层的硬度和耐蚀性等[1 4],但有关稀土在电沉积镍 钴合金中的作用的研究还未见报道。本文研究了在硫酸盐体系镍 钴合金电镀液中加入少量的稀土化合物后对电沉积过程、合金电极的催化性能、合金镀层的形貌和成分的影响。1　实验方法基础镀液成分(g/L)为NiSO4·7H2O200,CoSO4…     

退火前后镍钨硼合金电沉积层的结构与性能

采用电化学技术、XPS、DSC、XRD等方法研究Ni W B合金电沉积及热处理前后合金镀层的结构和显微硬度.结果表明,在Ni W B合金电沉积过程中伴随着化学沉积镍等过程以及Na2B4O7在镀层中的夹杂;Ni W和Ni W B合金电沉积层分别表现为纳米晶结构和非晶态结构;热处理过程中合金电沉积层发生晶粒粗化过程以及Ni W B合金镀层发生新相形成过程,产生Ni4W和镍硼化物如Ni2B、Ni3B等沉淀物;400 ℃热处理2 h后Ni W合金镀层有最大的显微硬度达919.8 kg•mm－2,而在500 ℃下Ni W B合金有最大的硬度达1132.2 kg•mm－2.     

铅锡合金薄层电沉积形态研究

研究铅锡合金薄层电沉积物的形态及其形态随电解液含不同铅锡离子浓度的转变.实验表明,沉积物呈现出不同的形态,包括枝晶型、分枝型、密枝型、分叉型和线状型.这些形态变化从根本上是由于晶体生长各向异性的变化和沉积物的生长速率不同造成的.     

泡沫镍的电沉积制备技术

采用化学预镀，电沉积，热处理工艺制备了厚度均匀，孔隙率高，具有较好抗拉强度和韧性和泡沫镍材料，报道了电化学方法制备泡沫镍的工艺技术和操作条件。     

单一稀土镧在不同基底上的电沉积及其性能的研究

研究在低温熔融盐体系中于不同基底上电沉积单一稀土金属镧（La）。经X-射线能谱仪测定,在镍片基底上沉积的La的质量分数为100％,铜片基底上沉积的La质量分数为72．84％;在镍铁合金灯丝上沉积得到La-Ni合金薄膜,其中La的质量分数为50．02％,Ni的质量分数为2．48％。经扫描电子显微镜观察,所得的沉积膜为均匀、光滑、致密的黑色沉积薄膜。经X-射线衍射仪分析,镧在不同基底上沉积所得的沉积膜为不同晶型,以镍片为基底得到的单质镧为α-六方晶型;以铜片为基底得到的单质镧为面心立方晶;均与基底晶型相匹配。在镍铁合金灯丝上电沉积所得的La-Ni合金薄膜致密均匀,在无水乙醇中久浸而不脱落,并呈现强磁性。     

离子液体在电沉积铝及铝合金中的应用

离子液体具有不挥发、不燃烧、热稳定性高、电化学窗口宽等特点,被认为是一种满足可持续发展和绿色化学需求的溶剂介质,因其在室温下可以电沉积出多种活泼金属及合金而备受关注。本文系统地介绍了近年来离子液体在电沉积铝及铝合金中的应用进展,分类概括了用于电沉积铝及铝合金的离子液体类型;综述了电沉积机理;对不同形貌的金属铝以及二元、三元铝合金的电沉积技术进行了详细的阐述;最后探讨了当前离子液体在电沉积铝及铝合金理论与技术研究中存在的问题,并对其发展方向进行了展望。     

负离子对紫精光还原和电氧化还原性能的影响

负离子对紫精光还原和电氧化还原性能的影响冯敏辉，刘伟区，梁兆熙（中山大学高分子研究所，广州，５１０２７５）关键词紫精化合物，负离子，电氧化还原，光还原，化学还原合成了不同负离子（Ｆ－、Ｃｌ－、Ｂｒ－、Ｉ－、ＳＣＮ－、ＣｌＯ４－）的芳基紫精聚合物，并研...     

铜电极上Zn—Co—P合金电沉积行为

铜电极上Ｚｎ┐Ｃｏ┐Ｐ合金电沉积行为黄清安＊陈永言邓伯华（武汉大学化学系武汉４３００７２）关键词铜电极，Ｚｎ－Ｃｏ－Ｐ合金，电沉积１９９６－０４－２３收稿，１９９６－０９－１３修回国家自然科学基金资助课题为了提高Ｚｎ层的耐蚀性，出现了含磷的锌基合金，...     

镍钨硼合金电沉积机理及镀层微晶尺寸

应用循环伏安、恒电位阶跃和X射线衍射 (XRD)等方法研究了Ni_W_B合金电沉积特点和镀层微晶尺寸 .结果表明 ,在以柠檬酸铵为络合剂的溶液中 ,Ni_W_B合金沉积层较Ni_W合金有较低的电化学活性 .电位阶跃i～t曲线分析表明 ,在玻碳电极上Ni_W_B合金电结晶过程遵循扩散控制瞬时成核三维成长模式 ,且随过电位的增加 ,电极表面晶核数增多 .XRD测试结果表明 ,随沉积电流密度提高 ,合金镀层微晶尺寸逐渐增大 ,说明电流密度提高将更加有利于Ni_W_B合金电结晶过程中的晶核生长 .     

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.