靛蓝衍生物的电子转移研究

合成了两个N,N′-取代的靛蓝染料,反式-N,N′-双对硝基苯甲酰基靛蓝(1)和反式N,N′-双间硝基苯甲酰基靛蓝(Ⅱ)。研究了这两个染料与电子给体(胺类化合物)或与电子受体(紫精化合物)之间的电子转移。结果表明,这两个染料在激发单重态经荧光猝灭,被紫精猝灭的速度常数(k_q)比被胺猝灭的速度常数大。     

γ-Mo_2N和分子筛负载的钼氮化物的结构表征

采用程序升温氮化的方法制备了分子筛负载的钼氮化物催化剂,并用EXAFS方法研究了氮化前后Mo原子的局域配位情况.氮化前负载MoO_3样品的径向结构函数中有三个峰,其中前两个峰对应着最近的Mo-O配位壳层,但是第一个峰与第二个峰的比例比晶体MoO_3中的比例大很多,表明分子筛负载的MoO_3具有更紧密的结构.氮化以后,Mo_2N样品的径向结构函数中有三个峰,对应于一个Mo－N和两个Mo－Mo配位壳层,与面心立方模型符合得很好.根据XRD和EXAFS谱的计算表明,Mo_2N中的N原子使Mo－Mo键拉长并削弱.分子筛负载的Mo2N样品具有与非负载Mo_2N样品近似相同的径向结构函数,只是对应于Mo－N壳层的峰较弱,表明负载的Mo_2N具有更大的结构无序性.     

N，N－二甲基甘氨酸乙酯分解反应机理的理论研究

利用量子化学计算方法MP2／6－31＋G^*研究了N，N－二甲基甘氨酸乙酯在气 相中热分解反应机理，并计算了反应的协同性，得出此反应是一个多步反应过程。 主要有两个阶段：第一个阶级是N，N－二甲基甘氨酸乙酯热分解产生N，－N二甲基 甘氨酸中间体和乙烯，第二个阶段是N，N－二甲基甘氨酸进一步分解生成三甲氨和 二氧化碳。第一个反应阶段为速率控制步骤。研究表明，该反应机理是一个非协同 的质子转移过程。计算结果与实验值吻合。     

N,N-二甲基乙醇胺三个季铵盐衍生物的合成与表征

以N，N－二甲基甲酰胺为溶剂，乙酸乙酯为催化剂，N，N－二甲基乙醇胺分别与苄基氯、十二烷基溴和十八烷基溴作用，得到了3个N，N－二甲基乙醇胺的季铵盐衍生物。标题化合物结构经IR，^1H NMR,^13C NMRt FAB-MS表征。     

新疆药桑叶多糖的分离纯化及结构研究

研究了新疆药桑叶多糖的分离纯化及初步的结构分析。采用DEAE-Cellulose-52及Sephadex G-200分离纯化药桑叶多糖,采用聚酰胺薄层层析及GC法测定药桑叶多糖的组成,凝胶过滤法测定其相对分子质量,红外光谱测定其苷键类型。粗多糖经DEAE-52分离得到6个多糖级分W1、W2、N1、N2、N3和N4,其中的4个级分W1、N1、N2和N4经Sephadex G-200纯化后,各个级分的洗脱峰均为单一对称峰。聚酰胺薄层法及GC法确定药桑叶多糖由葡萄糖、半乳糖、甘露糖、鼠李糖、阿拉伯糖及木糖等单糖组成。测得W1、N1、N2和N4的分子量分别为71 331Da,60 049Da,35 825Da和21 374Da。红外光谱中有典型的多糖吸收峰及α-型糖苷键。     

为什么N_2分子和C_2H_2分子里的三键活动性截然两样?

N_2分子的电子结构可简单地写为:N≡N:即两个 N 原子之间有一个σ键,二个π键。同时,每个 N原子还有一对“孤对电子”。乙炔分子的电子结构可简单地写为:H—C≡C—H即两个 C 原子之间有一个σ键,二个π键。另外,每个 C 原子与一个 H 原子间有一个σ键。对比 N_2分子与 C_2H_2的电子结构,可以看出在 N_2     

一个新的芳香性判据

Huckel的(4N+2)规则是关于环状共轭分子芳香性的规则。为什么具有(4N+2)个π电子的环是芳香性的,而具有4N个π电子的环是反芳香性的?对于这个问题,曾提出过     

N,N′-二芳基己二酰二肼类化合物的合成及其结构表征

报道了N,N′-二芳基己二酰二肼类化合物的合成方法。以自制的己二酰二氯、取代苯肼为原料,以二氯甲烷为溶剂,用冰浴法合成了9种新型的N,N′-二芳基己二酰二肼类化合物。产品的结构经元素分析、IR、1HNMR等测试技术得到确证,产物的IR谱中,在3 200～3 400 cm-1出现2个N—H吸收峰,1H NMR谱中,在δ7.3～10.5之间有2个N—H吸收峰,产品的元素分析结果与理论值基本相符。收率81%～93%。     

自由基C59N及双体(C59N)2的理论研究

用INDO系列方法对自由基C59N及双体(C59N)2进行了理论研究,结果表明: N的掺入使C60笼发生畸变, N向笼外突出, 碳氮6-6键上的C自旋密度较大, 两C59N自由基在这个碳上以C-C单键连接形成双体为C2h, C2v对称性。其中C2v构型更稳定, 且N与附近的三个碳均以单键连接。理论计算的电子光谱与实验吻合较好。(C59N)2易分解为单体C59N。     

N-酰基-N′-茄呢基哌嗪衍生物的合成及生物活性

以茄呢醇为起始原料和茄呢基哌嗪为关键中间体合成了 4个N 酰基 N′ 茄呢基哌嗪 ( 4a～ 4d) ,以及 2个含葡萄糖单元的N ( 2 全乙酰葡萄糖基苯甲酰基 ) N′ 茄呢基哌嗪 ( 5 )和N ( 2 葡萄糖基苯甲酰基 ) N′ 茄呢基哌嗪 ( 6) ,共 6个新茄呢基哌嗪衍生物 .其结构经元素分析 ,IR ,1HNMR和MS确证 .测试了化合物 4c ,5 ,6对三种人癌细胞 (Bel 740 2 ,KB ,HCT 8)的体外生理活性 ,初步结果表明化合物 6比 4c和 5对三种所测细胞有更好的抑制效果     

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.