共查询到20条相似文献,搜索用时 93 毫秒
1.
氢氧化2,9,16,23-四羧基酞菁合铁(Ⅲ)与硫醇轴配反应 总被引:1,自引:0,他引:1
用分光光度法研究了酞菁合铁[Fe(Ⅲ)Pc(COOH)4OH-]与β-羟基乙硫醇(HOCH2CH2SH)的轴向配位反应热力学,求得了配位数(n),稳定常数(βn)及热力学参数ΔrH0m、ΔrS0m。用停流法研究了[Fe(Ⅲ)Pc(COOH)4OH-]与β-羟基乙硫醇及苯硫酚的轴配反应动力学,讨论了反应机理,求得了预平衡步的平衡常数(K)和速控步的速率常数(k);研究了温度等诸因素对反应动力学的影响,得到了预平衡的ΔrH0m、ΔrS0m和速控步的活化参数Δ≠Hm、Δ≠Sm 相似文献
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价电子能级连接性指数及其应用 总被引:46,自引:2,他引:44
价电子能级连接性指数( fE)被定义为: fE=Σ(mi·mj…)-0.5,m为价电子能级值。其中0、1阶指数公式分别为: 0E=Σ(mi)-0.5、 1E=Σ(mi·mj)-0.5。 0E、 1E与化合物的总键能(ΔE)、晶格能(U)、标准生成焓(ΔfH?m)以及非金属氢化物的pKa呈现高度相关性。它们的线性回归方程为:ΔE=-48.0095+1402.94631E,r=0.9474, U=-328.0770+1541.9351 1E, r=0.9801,-ΔfH?m=-266.9299+1324.6461 1E, r=0.9509, pKa=-20.9723+28.1756 1E, r=0.98884, pKa=-14.6102-7.835 0E+40.6461 1E, R=0.9933。m、fE具有物理意义明确、计算方法简单等优点,而且预测结果令人满意。 相似文献
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通过紫外-可见光谱探讨了水溶液中α-环糊精(CD 1),β-CD 2,七(2, 6-二-o-甲基)-β-CD 3和γ-CD 4与D-、L-、D,L-苯丙氨酸(Phe)形成超分子包合物的稳定常数(K)。手性或外消旋苯丙氨酸与同一主体结合能力的强弱顺序为:L- >D,L- >D-Phe,各体系的KL/KD值在1.65~3.01之间,给出了较好的异构体分离。但三种形式的苯丙氨酸与这些主体的缔合常数均较小(K< 3×102mol·L-1)。就不同主体而言,K值的次序为:3 >1 >4 >2,并不完全等同于KL/KD的顺序:2 >1 >3 >4。 相似文献
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Ten solid complexes of zinc nitrate with L-α-leucine(Leu), L-α-valine(Val), L-α-tryptophan(Try) and L-α-threonine(Thr) were prepared in water. The compositions of these complexes are determined by chemical analysis and elemental analysis, which are identified as Zn(Leu)(NO3)2·2H2O(A), Zn(Leu)2(NO3)2·H2O(B), Zn(Val)(NO3)2·2H2O(C), Zn(Val)2(NO3)2·H2O(D), Zn(Val)3(NO3)2·H2O(E), Zn(Try)(NO3)2·2H2O(F), Zn(Try)2(NO3)2·H2O(G), Zn(Thr)(NO3)2·2H2O(H), Zn(Thr)2(NO3)2·H2O(I) and Zn(Thr)3(NO3)·H2O(J). The constant-volume combustion energies of the complexes, ΔcU(complex), were determined by a precise rotating bomb calorimeter at 298.15K. Standard enthalpies of combustion,ΔcHm?(complex, s, 298.15K), and standard enthalpies of formation, ΔfHm?(complex,s,298.15K) for these complexes were calculated as (4523.22±2.08), (7208.86±4.28), (3442.21±1.85), (5971.21±3.32), (9007.26±4.24), (5802.35±2.14), (10891.58±3.01), (2147.40±1.28), (4120.83±0.99), (6444.68±3.85)kJ·mol-1 and (615.67±2.27), (1863.16±4.60), (1017.34±2.00), (1742.93±3.61), (2245.70±4.73), (1161.18±2.61), (1829.71±4.20), (1632.82±1.43), (1885.55±1.50), (2770.25±4.21)kJ·mol-1, respectively. 相似文献
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不对称双二茂铁脲衍生物的合成、表征及电子传递性质 总被引:2,自引:0,他引:2
以二茂铁为原料,通过多步反应,首先合成了对称的桥联双二茂铁脲(5),再将其与胱胺反应,合成了一种新的不对称桥 联双二茂铁脲衍生物MeOOC-Fc-NH-CO-NH-Fc-CO-NH-(CH2)2-S-S-(CH2)2-NH2 (7)(Fc:二茂铁)。对目标产物进行了红外、紫外、1H NMR和MS表征;由于目标化合物7含有不对称的二茂铁脲这一特殊结构,采用循环伏安(CV)方法对化合物7的电子迁移特性进行了研究。结果表明2个二茂铁之间通过脲键传递电子,从而使2个二茂铁基团可以分别被氧化,它们的氧化电位差ΔEo?为181 mV,它们之间的稳定常数Kc为1 145。相对于对称的二茂铁脲(5)(ΔEo?=140 mV,Kc=207),这种不对称结构分子中2个二茂铁之间电子间的相互作用增强。 相似文献
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以5-(三氟甲基)吡啶-2-羧酸(Htpc)与DyCl3·6H2O、TmCl3·3H2O构筑了2种异质同晶的单核配合物[M(tpc)3(H2O)3]·H2O,其中 M=Dy (1)、Tm (2)。配合物 1 和 2 均为单斜晶系,P21/c 空间群,中心金属离子为八配位且形成了轻微扭曲的十二面体构型。温度梯度下的荧光和紫外测试表明,2 种配合物均能与牛血清白蛋白(BSA)发生静态猝灭作用,猝灭常数(Ksv)为 105~106 L·mol-1。配合物与BSA结合过程的ΔH和ΔS均为正值,说明疏水作用在其中扮演重要的角色。25℃时,2种配合物与BSA结合常数约为104 L·mol-1,表明二者与BSA的具有中等强度的结合力。 相似文献
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以5-(三氟甲基)吡啶-2-羧酸(Htpc)与DyCl3·6H2O、TmCl3·3H2O构筑了2种异质同晶的单核配合物[M(tpc)3(H2O)3]·H2O,其中M=Dy(1)、Tm(2)。配合物1和2均为单斜晶系,P21/c空间群,中心金属离子为八配位且形成了轻微扭曲的十二面体构型。温度梯度下的荧光和紫外测试表明,2种配合物均能与牛血清白蛋白(BSA)发生静态猝灭作用,猝灭常数(Ksv)为105~106 L·mol-1。配合物与BSA结合过程的ΔH和ΔS均为正值,说明疏水作用在其中扮演重要的角色。25℃时,2种配合物与BSA结合常数约为104 L·mol-1,表明二者与BSA的具有中等强度的结合力。 相似文献
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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%. 相似文献
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Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction
Laurent Gavara Thomas Boisse Jean-Pierre Hénichart Adam Daïch Philippe Gautret 《Tetrahedron》2010,66(38):7544-5571
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. 相似文献
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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. 相似文献
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Rebecca J. Burton Mandy L. CrowtherNeal J. Fazakerley Shaun M. FilleryBarry M. Hayter Jason G. KettleCaroline A. McMillan Paula PerkinsPeter Robins Peter M. SmithEmma J. Williams Gail L. Wrigley 《Tetrahedron letters》2013
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. 相似文献
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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. 相似文献
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N. A. Nedolya 《Chemistry of Heterocyclic Compounds》2008,44(10):1165-1219
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. 相似文献
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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. 相似文献
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《Tetrahedron》2014,70(21):3377-3384
The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative. 相似文献
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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. 相似文献