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1.
锌盐是微量元素的常用制剂,治疗范围广,疗效确切,生物学功能作用独特,但锌盐口服时,常引起食欲减退、恶心、呕吐、腹痛和白细胞减少症等副作用,尤以儿童反应为甚。  相似文献   

2.
The cross-coupling reaction of highly functionalized organozinc reagents with chloroacetyl chloride mediated by copper allows for the easy preparation of functonalized α-chloromethyl ketones in excellent yields.  相似文献   

3.
Unsymmetrical allyl-allyl couplings occur between allylstannanes and allyl acetates catalyzed by palladium(O) and a novel direct coupling of an allyl acetate in the presence of a distannane and a palladium(O) catalyst is also possible.  相似文献   

4.
"A new method of TiN/Si3N4 nanocomposite synthesis was described and tested. TiCl4 and SiCl4 used as the starting materials and sodium as the reduction agent were conducted in liquid ammonia respectively. TiCl4 and SiCl4 were reduced simultaneously and titanium nitride/silicon nitride nanocomposite powderswere obtained by in situ co-deposition at temperatures around ~ 45 oC. X-ray diffraction patterns indicate that the product was amorphous and the by-product was sodium chloride. The product powders were heated up to 1600 oC and crystallization to TiN and fi-Si3N4 happened. Due to presence of TiN, the crystallization of silicon nitride in the mixture was later than that of pure silicon nitride. Transmission electron microscopy images show the average size of powders range from 10 nm to 40 nm and scanning electron microscopy images conformed that Ti and Si elements were dispersed uniformly. A green bulk nitride composite containing 20%TiN with the mean grain size of 100-300 nm and fracture toughness of 10.1§1.1 m1=2MPa , was obtained by spark plasma sintering at 1500-1600 oC. The effect of TiN additiven microstructure and mechanical properties of composite bulk was discussed."  相似文献   

5.
《Analytical letters》2012,45(2):171-175
Abstract

Spectrophotometric observations, electrochemical data, esr spectrum and cryoscopic measurements in solutions of sulfur in liquid ammonia are reported. They indicate that the sulfur species present at low temperatures is S2NH3. At room temperature the predominant species is SNH3.  相似文献   

6.
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8.
3-Bromothiophene can be prepared on a scale of several moles by treatment of 2-bromothiophene with an excess of sodamide in liquid ammonia and subsequent quenching of the reaction mixture with solid ammonium chloride.  相似文献   

9.
An apparatus for titrations in liquid ammonia is described. The titrations can be carried out in the absence of air, and the utility of the apparatus is demonstrated for a number of conductometric and potentiometric titrations.  相似文献   

10.
《Analytical letters》2012,45(7):549-560
Abstract

At -40°C, the behavior of lO compounds, differing widely in their standard potentials, has been investigated in liquid ammonia, using cyclic voltammetry at a smooth platinum electrode. The purpose of this study was the realization of a redox scale with reversible systems. With azobenzene, pyridazine, cin-noline, benzocinnoline and 4,4′-azobis-(pyridine-N-oxide), the first electron transfer is reversible and leads to the formation of the corresponding radical anions which are stable; the second electron transferleads to the ciianions which can be protonated yielding the corresponding hydrazo. Other compounds, such as azoxybenzene, 3-amino-1,2,4-triazine, pyridine-N-oxide, 8-azaadenine and 1H-tetrazole, have an electrochemical behavior which i s more intricate.  相似文献   

11.
徐聪  周大鹏  刘丹  吴建一 《化学通报》2016,79(9):860-863
分别以4种离子液为新型助溶剂,以对甲苯磺酸(TsOH)和氯磺酸(ClSO3H)为反应原料,以二氯乙烷为溶剂,制备了对甲苯磺酰氯(TsCl)。着重研究了离子液对TsOH在二氯乙烷和硫酸中的溶解度比s及TsCl产率的影响。研究结果表明,离子液的加入可显著提高TsOH的s值,进而提高TsCl的产率。在4种离子液中,[BuPy]BF4的效果最佳。当[BuPy]BF4的用量为2(wt)%时,s值和TsCl的产率分别达12.5和87.36%。同时,考察了反应物配比、反应温度及反应时间对TsCl产率的影响。通过正交实验得到较优的反应条件为:n(ClSO3H):n(TsOH)为1.5:1,反应温度为25℃,反应时间为2h。  相似文献   

12.
膜乳化-液中干燥法制备单分散高分子微球   总被引:6,自引:0,他引:6  
粒径可控的单分散高分子微球,在分析化学中可用作高效液相色谱填料[1,2];在化学工业中可用作催化剂载体;在生物领域中用于药物释放、癌症与肝炎等临床诊断、细胞标记与识别等[3].高分子微球的制备方法大致可分为两类,一是利用由单体出发的聚合反应或缩聚反应形成微球,二是高分子溶液经物理或物理化学手段处理后形成微球[4]  相似文献   

13.
Abstract

Although numerous investigations on the chemistry of organic sulfenamides, for example, studies on the S–N torsional barrier,1 the electronic nature of the S–N bond2 and some nucleophilic substitutions on sulfur or nitrogen atom3 have been known, no example of nucleophilic substitution on arylcarbon of aromatic sulfenamides has been reported.  相似文献   

14.
ZnPt(CN)4 was shown to be an effective material for ammonia sensing, and can be synthesized using either solution or mechanochemical methods. A combination of luminescence and Raman spectroscopy revealed that multiple species are involved in the reaction between ammonia and ZnPt(CN)4. The crystal structure of one of these species, Zn(NH3)2Zn(NH3)3(Pt(CN)4)2, was elucidated. Detection of ammonia vapor down to 50 ppm in air was accomplished by monitoring the luminescence spectrum. The reaction between ZnPt(CN)4 and ammonia vapor is reversible, and can be cycled multiple times by either flowing air over the material or heating. ZnPt(CN)4 also has a relatively high thermal stability, decomposing only when heated above 420 °C.  相似文献   

15.
建立了测定电子烟烟液中的氨含量离子色谱法。样品经10 mol·L-1盐酸溶液萃取10 min后,采用Dionex Ion Pac CS16A阳离子交换柱分离,以MSA为淋洗液进梯度洗脱,用电化学检测器检测。氨的质量浓度在0.05~1.0 mg·L-1范围内与峰面积呈线性关系,检出限(3S/N)为0.035μg·g-1,测定下限(10S/N)为0.12μg·g-1。方法用于12种市售品牌电子烟烟液中氨的测定,加标回收率在93.2%~106%之间,测定值的相对标准偏差(n=5)小于4%。  相似文献   

16.
传统的呐偶合反应必须在无水有机溶剂条件下, 由金属或金属化合物促进羰基化合物进行呐偶合反应. 曾经报道过金属锌在强碱介质或弱酸介质中, 促进羰基化合物进行水相呐偶合反应. 本文报道一种简便、有效的水相呐偶合反应, 它是在含有少量冠醚的稀氨水溶液中, 使用锌粉促进醛基化合物进行水相呐偶合反应, 其中加入少量的冠醚有助于提高反应的产率, 呐醇产率由63%提高到84%. 然而, 呐偶合反应的产率受到羰基周围环境的立体位阻影响较大, 在此条件下, 锌粉能有效地促进芳香族醛类化合物进行水相呐偶合反应, 得到的呐醇产率高, 但非对映异构体选择性差, 而脂肪族醛类化合物得到的呐醇产率较低, 在同样的条件下, 酮类化合物不能顺利进行呐偶合反应.  相似文献   

17.
传统的(口片)呐偶合反应必须在无水有机溶剂条件下,由金属或金属化合物促进羰基化合物进行(口片)呐偶合反应.曾经报道过金属锌在强碱介质或弱酸介质中,促进羰基化合物进行水相(口片)呐偶合反应.本文报道一种简便、有效的水相(口片)呐偶合反应,它是在含有少量冠醚的稀氨水溶液中,使用锌粉促进醛基化合物进行水相(口片)呐偶合反应,其中加入少量的冠醚有助于提高反应的产率,(口片)呐醇产率由63%提高到84%.然而,(口片)呐偶合反应的产率受到羰基周围环境的立体位阻影响较大,在此条件下,锌粉能有效地促进芳香族醛类化合物进行水相(口片)呐偶合反应,得到的(口片)呐醇产率高,但非对映异构体选择性差,而脂肪族醛类化合物得到的(口片)呐醇产率较低,在同样的条件下,酮类化合物不能顺利进行(口片)呐偶合反应.  相似文献   

18.
19.
The sodium/liquid ammonia cleavage of the dimethoxybenzenes and related substances, reported in large part by Birch in 1947, has been re-examined with use of improved techniques. Remarkable patterns of reactivity (e.g., ortho > meta > para) that he described are confirmed and extended. They are agreeably rationalized by means of a simple, approximate adaptation from MO theory.  相似文献   

20.
X-ray absorption fine structure (XAFS) measurements have been performed at -50 degrees C on a 0.4 mol dm(-)(3) copper(II) nitrate solution in liquid ammonia. Extended X-ray absorption fine structure (EXAFS) spectroscopy was used to determine the coordination number and bond distances for the solvated copper(II) ion in solution. The equatorial ammonia nitrogens are located 2.00 ? from the copper and the axial nitrogen 2.19 ? from the copper. However, it was not possible from the EXAFS analysis alone to conclude whether there was one or two axial nitrogens. Therefore, X-ray absorption near-edge structure (XANES) spectroscopy was combined with discrete variational Xalpha (DV-Xalpha) molecular orbital calculations for a series of five- and six-coordinated models to determine the coordination number and the geometry. The experimental XANES spectrum was best reproduced by a model where the copper(II) ion is pentacoordinated in liquid ammonia in a square pyramidal geometry with the copper(II) ion lifted above the average nitrogen plane.  相似文献   

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