常见酸根阴离子对镁与水反应的影响

一、问题的提出镁不能跟氢氧化钠等碱溶液反应,但能与碱性银氨溶液反应生成氢气等产物。究其原因,有人认为是“反应途径不同”的缘故[1]：镁与氢氧化钠等碱溶液反应时,其表面形成了难溶的氢氧化镁,阻止了反应的进行;镁与银氨溶液反应时,镁先将银氨络离子中的银置换出来,使镁表面形成了Ag—Mg原电池,发生的是原电池反应：正极：2H2O＋2e→2OH－＋H2负极：Mg＋2OH-－2e→Mg（OH）2为了考察这一解释的可信度,笔者进行了下列2则实验。实验1（1）按文[1]方法用硝酸银和稀氨水制取少量银氨溶液;（2）把光亮的镁条置于银氨溶液中,…     

利用紫外光离子源高场不对称波形离子迁移谱快速、现场检测水中氨的含量

氨是水体主要的污染物之一,其含量是水质评估的重要参数。本研究采用真空紫外光离子源-高场不对称波形离子迁移谱(Ultraviolet photoionization high field asymmetric waveform ion mobility spectrometry, UVFAIMS)技术,发展一种的水中氨含量的现场快速检测方法。通过对比标准氨样品和水中微量氨UV-FAIMS 谱图峰的特征补偿电压(Compensation voltage, CV)值,确定了水中HN+4的特征离子峰位置;研究了不同分离电压(Dispersion voltages, DV)下HN+4谱图峰位置的关系,获得了HN+4的特征识别系数α2和α4分别为2.21×10-5 Td-2和-1.45323×10-9 Td-4;通过不同浓度样品的信号响应,研究了UV-FAIMS 对水中氨的检出限,在信噪比为3的情况下达到了9.2 μg/ L。本研究为水中氨现场检测提供了一种快速、无需前处理的技术手段。     

板状镍催化剂上氨分解和氨部分氧化制氮氢气的研究

研制了一种 Ni/Al₂O₃多孔板状催化剂.该催化剂在反应温度高于750℃,氨分解率高于99.5%时,允许反应空速达10000—40000h^-1.用该催化板组装的反应器可采用内加热形式,和一般的外加热反应器相比可节约能耗约30%.在催化板上氨分解的经验动力学方程是γ=kp²NH₃,表观活化能为153.0kJ/mol.将该催化剂用于氨部分氧化时,在空气和氨比为1.0—1.7,680—750℃,氨空速10000—40000h^-1条件下,在氨点火后无外加能源情况下,能制得含氢30～43%,残氧小于0.1%的氮氢混合气,氨的转化率>99.5%,连续250小时反应表明,催化剂活性稳定.宏观动力学研究得出,反应对氨呈零级,表观活化能为37.2kJ/mol.     

Ti(O-iPr)4-NaNp-N2固氮体系和锆、铁氢化物的反应

在前报中,我们用锆、铁氢化物和[Mo(N_2)_2(dppe)](Ⅰ)(dppe=(C_6H_5)_2P-CH_2-CH_2-P(C_6H_5)_2)及其类似物[C_6H_5N_2]BF_4(Ⅱ)进行反应,经红外光谱测定发现产物中有—NH基因,此反应产物水解后生成氨.这一结果表明锆,铁氢化物上的氢已转移到配位N_2分子上.这有两种情况,一是反应产物需要经过水解后生成氨,(Ⅰ)和锆、铁氢化物的反应属于这一类;另一是反应直接生成游离氨,产物不需要经过水解,铁的氢化物和     

靶向鞘氨醇激酶1的Jaspine B类似物的合成及抗肿瘤活性研究

Jaspine B,又称为pachastrissamine,是从冲绳海绵Pachastrissa sp和Jaspis sp中分离得到的一种天然存在的脱水植物鞘氨醇衍生物,其异构体2?epi?jaspine B对鞘氨醇激酶和肿瘤细胞系具有强效抑制活性.在此基础上,我们通过对2?epi?jaspine B进行结构修饰制备其...     

合成氨反应动力学平衡常数与热力学平衡常数的关系

根据当前普遍被接受的氨合成和氨分解机理,明确了氨合成及分解反应的速度控制步骤,确定了氨合成和氨分解反应的动力学方程,进而导出合成氨反应的动力学平衡常数表达式,与热力学平衡常数进行了比较,明确了2者之间的关系。有助于理解合成氨热力学平衡常数与反应速率的关系。     

氨回收液中二氧化碳的测定

煤制气的副产品氨在回收时 ,工艺上对氨溶液中二氧化碳含量要求十分严格 ,因为二氧化碳与氨水形成碳酸铵结晶堵塞管道和腐蚀管道。原设计手册中的分析方法是先将氨溶液中的二氧化碳蒸出 ,用氢氧化钡溶液吸收 ,再用硫酸标准溶液滴定。该方法不但所需时间长 ,氢氧化钡溶液易吸收二氧化碳而形成碳酸钡沉淀 ,而且误差大。本法用过量氢氧化钠溶液吸收氨溶液中二氧化碳 ,再用硫酸滴定混合碱的滴定方法。在消除氨、硫化氢及氰化氢的干扰后 ,能快速准确地测定氨溶液中的二氧化碳含量。吸收和滴定反应如下 :ＣＯ2 +2ＮａＯＨ =Ｎａ2 ＣＯ3 +Ｈ2 Ｏ2Ｎ…     

复相光催化由水和氮气合成氨的研究

近年来随着太阳能光化学研究的进展,Schrauzer和Outh首先发现,在湿的TiO_2半导体粉末上,用光催化还原氮的方法。Fujishima等人用TiO_2、ZnO和SiC粉末在氮气的饱和水溶液里照射的方法合成了氨,但所得氨的产率很低。Miyama等人用掺入铂黑的TiO_2,ZnO_2,SrTiO_3,CdS,GaP半导体粉末和SiC的方法提高了氨的产率。用GaP-Pt时氨的     

N,N-二甲基-γ-氨丙基-γ-氨丙基聚二甲基硅氧烷ASO-121的合成、表征与膜形态

用八甲基环四硅氧烷（D4）与N，N-二甲基-γ-氨丙基-γ-氨丙基二甲氧基硅烷等进行聚合反应，合成了一种N，N-二甲基-γ-氨丙基-γ-氨丙基聚二甲基硅氧烷（ASO-121）柔软剂，用红外光谱、核磁共振氢谱、原子力显微镜等仪器对其结构和成膜形态进行了研究。结果表明，ASO-121能在棉纤维织物和单晶硅表面形成疏水膜，该膜表面略显粗糙，在2μm^2扫描范围内其均方根粗糙度达到了0．226nm。     

氨丙基官能化HMS介孔分子筛的合成及表征

沿S0I0路径,以十六胺为模板剂,以3-氨丙基三乙氧基硅烷为有机硅源,通过与TEOS共水解沉淀合成了氨丙基官能化HMS介孔分子筛.采用粉末X-射线衍射分析、N2吸/脱附、扫描电镜分析、高分辨透射电镜分析、傅立叶变换红外分析以及元素分析等表征手段,对所合成的材料进行表征.氨丙基官能化HMS介孔分子筛具有worm-like孔道结构,且较为均一的孔径分布.研究了前体硅源中3-氨丙基三乙氧基硅烷含量的变化对氨丙基官能化HMS介孔分子筛的相结构及织构性能的影响.傅立叶变换红外分析表明,NH2-CH2-CH2-CH2有机基团分布在杂化HMS介孔孔道中.     

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.     

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.     

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.     

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.     

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.