乙炔的制备与性质检验的一体化实验

正利用液封的集气瓶,对高中教材中"乙炔的制备与性质检验实验"进行一体化设计,改进后的实验具有反应容器装置简单、试剂用量少、环境友好等优点。1实验探究乙炔的制备和性质检验实验,选自高中《有机化学基础》~([1]),该实验装置搭建复杂;反应剧烈,易堵塞导管;试剂用量较大;Br_2的CCl_4溶液敞口放置,挥发有毒气体。针对以上问题,参照刘媛媛~([2])的实验方案,采用新型反应容器液封的集气瓶     

使用滴液式气体发生器制备乙炔

采用恒压分液漏斗和蒸馏烧瓶组成的装置,饱和食盐水与电石反应是实验室制备乙炔的常用方法。该实验产生糊状Ca(OH)₂沉淀,存在反应速率过快、无法控制反应进程、产生气流不平稳、泡沫随气体冲出堵塞导管等问题。利用滴液式气体发生器,在反应容器中加入7 mm玻璃珠与电石混合,以10%氯化铵溶液为反应液,解决了实验室制备乙炔存在的问题,同时也提高了制备乙炔的产率。     

一种用于离子色谱系统的免脱气碳酸盐淋洗液发生器系统

报道了一种免脱气碳酸盐淋洗液发生器系统(含碳酸盐发生器和pH调节器)。碳酸盐淋洗液发生器可在线将纯水转变成设定浓度的碳酸盐淋洗液,该淋洗液再通过电致p H调节器调节pH进而改变淋洗液中碳酸盐/碳酸氢盐的比例,最终实现分离选择性的灵活调控。通过该碳酸盐淋洗液发生器系统可以得到0.5～8 mmol/L之间任意浓度、碳酸盐/碳酸氢盐任意比例的碳酸盐淋洗液;所得淋洗液纯度高,结合离子色谱系统,可用于分析7种常见阴离子,其保留时间的日间相对标准偏差均小于0.76%。     

使用启普气体发生器的一点体会

启普发生器(Kipp)有这样的缺点:碎小的固体药品,常落入贮藏器B中,并且装备液体药品时(如酸液)用量相当大。为了解决这些问题,我采取了这样的一个方法,就是用一些小块的玻璃碎片,从排液口C填入贮藏器B中,最好能充满到A球的底处,然后再把需要的固体药品,放在这些玻璃碎片的上面(如图所示)。经过实验后,如制取氢气等,效果良好,这样一方面使在A球底处的碎锌块不会落入贮藏器B中,以免药品的浪费,另一方面由于在贮藏器B中已有玻璃碎片充满着,如果用需要装入1,000毫升酸液的启普发生器,常填充了玻璃碎片后,只要500毫升的酸液就够使用,因此每次可少装酸液二分之一左右。如果像这样改变装置,既可节约药品,使物尽其     

离子液体载催化剂和载试剂在有机合成中的应用

综述了离子液体载催化剂和载试剂在有机合成中的应用进展. 离子液体载催化剂是针对离子液体中催化剂难以回收利用的问题提出来的, 它不仅可以实现均相催化, 而且反应产物容易分离, 催化剂可以循环使用. 离子液体载有机试剂合成, 又称为离子液体相有机合成, 具有固相反应产物纯度高和液相反应反应快的优点. 在离子液体载无机试剂的反应中, 反应物毒性降低, 反应条件温和, 产物选择性好.     

流动注射—冷蒸气原子吸收法测定垃圾样品中泵

研究了反应介质浓度及其流速，反应管道长度，共存元素等对使用ＬＺ－１２００型流动注射氢化物发生器和ＷＦＸ－１０型原子有收分光光度计测定垃圾样品中汞的影响。方法准确度，精密均匀好，且操作简单，试剂用量少，分析速度快。经实验应用，结果满意。     

甲酸氧化反应动力学反应装置的改进

进行甲酸氧化反应动力学实验时,需要在反应前用去离子水清洗反应装置内壁。由于原反应装置（图1）存在缺陷,反应装置口使用橡皮塞,反应装置底部无活塞,每次换液时,需取出橡皮塞,倒出废液,洗净后再放回,操作不方便,而且容易损坏反应装置。在实验时,要将配制好的液体（水、溴、溴试剂、盐酸）加入到反应装置内,恒温并等待Br^-生成;但由于橡皮塞孔径较大,在加入甲酸之前,易有液体从橡皮塞孔径挥发,使液体浓度发生改变,影响实验结果。     

流动注射-冷蒸气原子吸收法测定垃圾样品中汞

研究了反应介质浓度及其流速、反应管道长度、共存元素等对使用LZ-1200型流动注射氢化物发生器和WFX-10型原于吸收分光光度计测定垃圾样品中汞的影响。方法准确度、精密度均好,且操作简单,试剂用量少,分析速度快。经实际应用,结果满意。     

便携式湿度发生器的研制

介绍一种便携分流式湿度发生器的工作原理及研制过程。该便携式湿度发生器利用分流法湿度发生原理,采用微控制器和质量流量控制技术实现了自动发生不同流量、不同露点气体的功能,可为露点测试仪检定和校准提供动态标准湿度气体。通过验证试验证明,该装置测量准确可靠。     

氢化物-原子吸收分光光度法的简便装置

氢化物-原子吸收分光光度法是近年来发展起来的一种新的分析方法。本文提出一个新结构的氢化物系统,包括氢化物发生器和自动加液装置(见图1)。氢化物发生器有一个多支管的磨口连接器。惰性气体、硼氢化钠溶液、去离子水分别由支管进入反应瓶。特点在于硼氢化钠溶液随惰性气体直冲反应瓶。这样既加入迅速,又得到充分搅拌试样溶液,省去了搅拌装置。磨口连接器底端有开细孔夹套,上通去离子水支管。按揿微动开关,即有去离子水冲洗反应瓶。连接器上端装有玻璃浮珠阀门,当反应瓶中压力超过浮珠自身重量时,反应气体便有力地冲入石英管炉。反应瓶底部装有活塞,可以排出废液。自动加液装置的     

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%.     

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.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

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.     

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.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

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.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

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.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

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.     

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.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

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.