共查询到20条相似文献,搜索用时 367 毫秒
1.
α,α一联吡咯是某些天然存在的活性吡咯化合物中关键组成, 关于手性联吡咯的研究已有详细的综述报道, 近年发现, 某些含N-取代氨基的空间阻碍吡咯有明显的生理活性和可贵的药理性质, N,N'-联吡咯中N-N键很容易发生均裂反应而生成游离基, 后者很可能与天然吡咯小分子的生理活性有密切关系, 这些都引起了人们的广泛兴趣。 相似文献
2.
N-乙酰乙酰基吡咯为有机合成上有用的起始原料和中间体。例如,可能作为合成Carbapenam类β-内酰胺化合物的原料。1977年,Wang Nam-Chiang和And- 相似文献
3.
4.
5.
6.
以二茂铁炔烃为原料通过“一锅法”环加成反应合成了一系列2,5-双二茂铁基-1-苯基-吡咯衍生物, 包括: 2,5-双二茂铁基-1-(3-三氟甲基苯基)-吡咯(1), 2,5-双二茂铁基-1-(4-氟苯基)-吡咯(2), 2,5-双二茂铁基-1-苯基-吡咯(3), 2,5-双二茂铁基-1-(4-乙基苯基)-吡咯(4)和2,5-双二茂铁基-1-(4-乙氧基苯基)-吡咯(5), 使用元素分析, 傅里叶变换红外(FTIR)光谱, 质谱(MS)和核磁共振(NMR)等手段对化合物进行了结构表征. 采用循环伏安法(CV), 密度泛函理论(DFT)模拟计算研究了苯基上取代基对双二茂铁间电荷交互的影响. 研究发现第一氧化电位(Ea1), 峰电位差(ΔE)与取代基的哈米特常数(σ), 吡咯1H NMR的化学位移(δ), 吡咯N原子自然轨道(NBO)电荷之间存在显著线性关联; 同时发现, N原子电荷密度升高, 双二茂铁间电荷交互能力减弱, N原子电荷密度降低, 双二茂铁间电荷交互能力提高. 因此这类双二茂铁基吡咯衍生物中N原子电荷密度对双二茂铁间电荷交互起着关键的影响作用. 相似文献
7.
8.
9.
10.
11.
12.
T. S. Chung Wei‐Yu Chen Yuhui Lin Kumari P. Pramoda 《Journal of Polymer Science.Polymer Physics》2000,38(11):1449-1460
We studied three kinds of ladderlike polyepoxysiloxanes, which have different side groups grafted on the ladderlike backbones. 1,3‐Bis(aminopropyl)tetramethyl disiloxane (diamine) was used as the curing agent. The reaction between ladderlike polyepoxysiloxanes and diamine was investigated by contact angle measurements and surface free energy study. Several factors such as diamine amount, reaction time, and temperature can affect the systems' surface tension (or surface free energy), which were determined by two‐liquid geometric and three‐liquid acid‐base methods. The experimental results showed that an increase in the diamine amount in the reaction systems results in an increase in the polar part of surface free energy because of electron donate characteristics of the diamine. However, because epoxy (electron acceptor) and diamine (electron donor) react fast at elevated temperatures, increasing reaction temperature decreases the polar part of the surface free energy, while increases the nonpolar part of the surface free energy. The evolution of surface free energy with time for various epoxy–diamine reaction systems at various temperatures has also been studied. It was found that it took a relatively long time (50–60 h) to reach the equilibrium state. The experimental results can be well interpreted by the epoxy–diamine reaction mechanism and van Oss–Good's Lewis acid‐base theory. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1449–1460, 2000 相似文献
13.
Adsorption mechanism of mixed cationic/anionic collectors in feldspar-quartz flotation system 总被引:5,自引:0,他引:5
The adsorption mechanism of mixed cationic alkyl diamine and anionic sulfonate/oleate collectors at acidic pH values was investigated on microcline and quartz minerals through Hallimond flotation, electrokinetic and diffuse reflectance FTIR studies. In the presence of anionic collectors, neither of the minerals responded to flotation but the diamine flotation of the minerals was observed to be pH and concentration dependent. The presence of sulfonate enhanced the diamine flotation of the minerals by its co-adsorption. The difference in surface charge between the minerals at pH 2 was found to be the basis for preferential feldspar flotation from quartz in mixed diamine/sulfonate collectors. The infrared spectra revealed no adsorption of sulfonate collector when used alone but displayed its co-adsorption as diamine-sulfonate complex when used with diamine. The presence of sulfonate increased the diamine adsorption due to a decrease in the electrostatic head-head repulsion between the adjacent surface ammonium ions and thereby increasing the lateral tail-tail hydrophobic bonds. The mole ratio of diamine/sulfonate was found to be an important factor in the orientation of alkyl chains and thus the flotation response of minerals. The increase in sulfonate concentration beyond diamine concentration leads to the formation of soluble 1:2 diamine-sulfonate complex or precipitate and the adsorption of these species decreased the flotation since the alkyl chains are in chaotical orientation with a conceivable number of head groups directing towards the solution phase. 相似文献
14.
A glucose‐functionalized diamine was prepared and used as a new monomer for polyurea synthesis. The diamine was prepared by N‐glycosylation of 1,6‐hexamethylenediamine with D ‐glucose. Upon adding diisocyanates to the diamine, isocyanate reacted selectively with the amino groups, not with the hydroxyl groups of the glucose‐derived structure, to give the corresponding polyureas. The polyureas exhibited highly hydrophilic nature due to the presence of the glucose‐derived side chain. A ternary system consisting of the glucose‐functionalized diamine, piperazine, and diisocyanate gave the corresponding polyureas, where content of the glucose‐derived moiety was tunable by feed ratio between the diamine and piperazine. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
15.
A bicyclic diamine with defined and stable conformation in solution was prepared from Kemp's triacid. The efficient four-step synthesis of the Boc-protected diamine requires only a single purification by column chromatography. X-ray analysis and NMR spectroscopy confirm the structure of the diamine in the solid state and in solution. 相似文献
16.
Optically active cofacial π-π phthalocyanine (Pc) stacked supramolecules were spontaneously and successfully generated from a mixture of four possible geometric isomers (C(4h), D(2h), C(2v), C(s)) of achiral 4(5),4'(5'),4'(5'),4'(5')-tetracarboxymetallophthalocyanine (tcPcM; M=Ni, Cu) induced by an equimolar amount of inexpensive chiral diamine molecular sources in DMSO/CHCl(3) mixed solvent under optimized conditions of the volume ratio of poor/good cosolvents, the molar ratio of chiral molecular diamine to tcPcM, the cavity metal of phthalocyanine, and the addition order of the amines. The sign and amplitude of circular dichroism spectra due to the supramolecular chirality and structure of the diamine molecules are impossible to remove by additions of the antipode diamine and trifluoroacetic acid. The chiral diamine was partly contained in nanofibers, and that retained in the solution can be recycled and reused to induce optically active tcPcM supramolecules. 相似文献
17.
A highly rigid diamine monomer derived from naturally occurring myo‐inositol and its use for polyamide synthesis 下载免费PDF全文
Atsushi Sudo Shou Sugita 《Journal of polymer science. Part A, Polymer chemistry》2016,54(21):3436-3443
A rigid diamine was synthesized from myo‐inositol, a naturally occurring cyclic hexaol, and used as a monomer to synthesize polyamides. myo‐Inositol was treated with 1,1‐dimethoxycyclohexane to yield a bisketal bearing two hydroxyl groups, and from this bisketal, the target diamine was synthesized in three steps: (1) derivation of the diol into the corresponding bistriflate, (2) nucleophilic substitution of the bistriflate with sodium azide yielding a diazide, and (3) reduction of the diazide to the target diamine. The target diamine readily underwent polycondensation with dicarboxylic acid chloride in solution. The resulting polyamides, whose main chain inherited the rigid 5‐6‐5 system from the diamine monomers, have high glass transition temperatures. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3436–3443 相似文献
18.
A series of linear polyurethaneureas was prepared by a two-step solution polymerization method. The prepolymer formed by the reaction of 4,4′-diphenyl methane diisocyanate with polyethylene glycol/polypropylene glycol was further chain extended with ethylene diamine/propane diamine/hexane diamine. The chemical shift values of various carbon species of the block copolymer were analyzed and assigned. The products formed due to the presence of water at different stages of polymerization were also characterized. 相似文献
19.
Although bioinspired sacrificial bonds have been demonstrated to be efficient in improving the mechanical properties of polymer materials, the effect of binding energy of a specific dynamic bond on the ultimate mechanical performance of a polymer network with dual-crosslink remains unclear. In this contribution, diamine and sulfur curing package are introduced simultaneously into a sulfonated cis-1,4-polyisoprene to create dually-crosslinked cis-1,4-polyisoprene network with sulfonate-aminium ionic bonds as the sacrificial bonds. Three diamines(primary, secondary and tertiary) with the same spacer between the two nitrogen atoms are used to create the ionic bonds with different binding energies. Although the binding energy of ionic bond does not affect the glass transition temperature of cis-1,4-polyisoprene(IR), it exerts definite influences on strain-induced crystallization and mechanical performance. The capabilities of diamine in dissipating energy, promoting strain-induced crystallization and enhancing the mechanical performance are in the same order of secondary diamine primary diamine tertiary diamine. The variations in mechanical performances are correlated to the binding energy of the ionic bond, which is determined by p Ka values. 相似文献
20.
Chromatographia - 1,6-Diaminohexane (DAH, 1,6-hexamethylene diamine) and isophorone diamine (IPDA) have been derivatized with trifluoroethyl chloroformate (TFECF) using a two-phase procedure.... 相似文献