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1.
全氟磺酸树脂Nafion NR50溶解的制备 总被引:8,自引:0,他引:8
研究了全氟磺酸树脂NafionNR50溶液的制备过程,通过考察不同的溶剂 体系,得到了5种对NafionNR50具有良好溶解作用的溶剂体系,即40%-70%水+60%-30%乙醇、40%-70%水+60%-30%正丙醇、10%-70%水+90%-30%异丙醇、30%-70%水+60%-20%正丙醇+10%甲醇和10%-70%水+80%-20%异丙醇+10%甲醇。适宜的溶解温度为230-250℃,溶解时间为4h。在溶解的过程中,NR50催化醇发生异构化、醚化和脱水等反应,甲醇起到促进NR50溶胀进而加速其溶解的作用。 相似文献
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建立了离子色谱法测定大豆木质部汁液中Cl~-、SO_4~(2-)、NO_3~-、PO_4~(3-)、柠檬酸和苹果酸的方法。Cl~-、SO_4~(2-)、NO_3~-、PO_4~(3-)、柠檬酸和苹果酸的检出限分别为0.01、0.04、0.05、0.05、0.30和0.10 mg/L,相对标准偏差分别为8.34%、4.68%、9.54%、6.86%、5.52%和7.50%,线性范围分别为0.5~50.0、1.0~100.0、0.5~50.0、1.0~100.0、5.0~100.0和1.0~100.0 mg/L,回收率分别为103%~106.7%、92%~98.7%、93%~95.5%、91.7%~92%、93.2%~106%和94%~108.3%。方法简便、快速,测定结果准确,无干扰。 相似文献
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韩晓 《中国无机分析化学》2016,6(3):27-31
采用盐酸+硝酸+氢氟酸+高氯酸溶解试样,通过样品酸浓度条件、分解条件、共存元素干扰等实验,建立了电感耦合等离子体原子发射光谱法测定铜原矿和尾矿中的铜、铅、锌、镍、钴、镉、镁和锰含量的方法.测定范围:ω(Cu):0.010%~2.50%,ω(Pb):0.005%~1.00%,ω(Zn):0.005%~1.50%,ω(Ni):0.005%~0.05%,ω(Co):0.005%~0.05%,ω(Cd):0.005%~0.015%,ω,(Mg):0.010%~8.00%,ω(Mn):0.005%~0.50%.经加标回收实验,各元素的加标回收率为86%~103%(n=3),方法准确、可靠,适用于铜原矿和尾矿的铜、铅、锌、镍、钴、镉、镁和锰量的同时测定. 相似文献
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建立了离子体发射光谱仪测定钢中铈元素的方法。为消除共存元素对铈分析游线的光谱干扰,选择Ce413.380nm作为分析线,铈含量在0.005%-0.50%之间工作曲线线性良好。对于含量范围在0.005%-0.10%的铈元素,回收率为85.6%-12.5%,测定结果的相对标准偏差小于9.74%(n=8);对于含量范围在0.10%-0.50%的铈元素,回收率为99.5%-103.0%,测定结果的相对标准偏差小于3.52%(n=8)。该方法适宜钢中含量范围在O.005%-0.50%的铈元素的测定。 相似文献
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酵素菌肥的金属元素营养分析 总被引:1,自引:0,他引:1
在磷酸根、硅酸根存在下以2%硝酸镧作机体改进剂,测定了酵素菌肥中多种金属元素的含量,各元素的平均回收率分别为:K98.69%,Ca100.37%,Mg97.81%,Na96.06%,Cu98.26%,Fe96.45%,Zn99.78%,Sr93.54%,Li94.22%。方法简便,快速可靠,肯定 酵素菌肥的金属元素营养价值。 相似文献
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根据1988年美国化学会化学文摘部所摘录的期刊和专利文献数的统计,在总数474545件中美国约占25%,日本将近20%,苏联约为12%。在期刊文献方面,美国发表的化学研究与开发方面的文章仍居首位,占27%,苏联为13%,日本为12%,西德为6.3%,英国为5.6%。但在专利文献中,大部分(54%左右)来 相似文献
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应用原子吸收光谱法测定了实验动物鼠饲料中Zn、Cu、Fe、Mn、Mg、K、Na7种微量元素的含量。结果表明,7种微量元素中,Zn、Cu、Na的含量达到国家标准,分别高于国家标准88.18%、14.91%和9.85%,Mn、Mg、K、Fe的含量低于国家标准42.71%、32.95%、14.56%和6.74%。7种微量元素测定的回收率为89.71%~101.45%。 相似文献
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以N,N-二甲基甲酰胺(DMF)为溶剂,丁酮为内标,采用PV-101毛细管色谱柱 (30 m×0.22 mm),氢火焰离子化检测器,建立兰索拉唑中五种有机溶剂甲醇、乙醇、丙酮、二氯甲烷、乙酸乙酯残留量的定量分析方法。五种有机溶剂检出限分别为0.002 4%,0.002 4%, 0.001 2%,0.000 6%,0.000 6%;在10-1000 mg·L-1浓度范围内,各组分线性关系良好;对应的平均回收率分别为100.8%±3.6%,102.1%±2.3%,99.97%±4.1%,99.63%±2.7%, 102.3%±3.5%。 相似文献
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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%. 相似文献
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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. 相似文献
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Uroš Grošelj Mojca Žorž Amalija Golobič Branko Stanovnik Jurij Svete 《Tetrahedron》2013,69(52):11092-11108
A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives. 相似文献
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The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp3)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp2)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp2)?H and aliphatic 1,5- and 1,6-C(sp3)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp3)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp2)?H insertion. 相似文献
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A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL. 相似文献
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Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction
Laurent Gavara Thomas Boisse Jean-Pierre Hénichart Adam Daïch Philippe Gautret 《Tetrahedron》2010,66(38):7544-5571
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. 相似文献
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A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions. 相似文献
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N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%). 相似文献
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Shashikant U. Dighe Surya K. Samanta Shivalinga Kolle Sanjay Batra 《Tetrahedron》2017,73(17):2455-2467
An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y1 and Y2. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones. 相似文献
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In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates. 相似文献