排序方式: 共有39条查询结果,搜索用时 0 毫秒
31.
The title compounds contain groups (amine, amide, imine, carboxylic acid) that are capable of forming intramolecular hydrogen bonds involving a six-membered ring. In compounds where the two interacting functional groups are imine and carboxylic acid, the imine is protonated to give a zwitterion; where the two groups are imine and amide, the amide remains intact and forms a hydrogen bond to the imine nitrogen. The former is confirmed by the iminium 15N signal, which shows the coupling of 1J(15N,1H) -85 to -86.8 Hz and 3J(1H,1H) 3.7-4.2 Hz between the iminium proton and the methine proton of a cyclopropyl substituent on the iminium nitrogen. Hydrogen bonding of the amide is confirmed by its high 1H chemical shift and by coupling of the amide hydrogen to (amide) nitrogen [(1J(15N,1H) -84.7 to -90.7 Hz)] and to ortho carbons of a phenyl substituent. Data obtained from N,N-dimethylanthranilic acid show 15N-1H coupling of (-)8.2 Hz at 223 K (increasing to (-)5.3 Hz at 243 K) consistent with the presence of a N... H-O hydrogen bond. 相似文献
32.
33.
Horst K. Neudeck 《Monatshefte für Chemie / Chemical Monthly》1988,119(5):625-644
The title compound6 a was prepared by cyclisation of the diacid4 b. The diester4 a of4 b was synthesized by alkylation of2 with3 and following Retro-Claisen-reaction. After catalytic reduction of6 a to8 a two identical substituents were introduced byFriedel-Crafts-reaction (28). By transformation of the acetylgroups several other derivates (29–36) could be obtained. The unsymmetrical compounds (e.g.21) were prepared from20, whose precurser was the spiroketon10 a. 相似文献
34.
关于苯及其衍生物在盐水溶液中的活度系数的研究 总被引:5,自引:0,他引:5
摘录了25℃时苯,甲苯,邻位、间位、对位二甲苯,间位、对位二氯苯及萘在NaF,LiCL,NaBr,NEt~4Br等25种盐的水溶液中的活度系数f,它们的lgf-c~s的关系符合Setchenow盐效应公式。计算了苯及其衍生物在上述25种盐水溶液中的各种盐效应理论的k~s,主要有:1)Debye-macAulay静电理论;2)Conway-Desnoyers-Smith静电理论;3)Masterton-Lee定标粒子理论;4)McDevit-Long内压力理论;5)改进的内压力理论;6)改进的Bockris色散力理论。对各种理论值比较后可以看到改进后的内压力理论k~s值与实验k~s值较为吻合。Bockris色散力理论经改进后计算比较简单,可以判断盐效应符号,盐效应顺序也基本正确。 相似文献
35.
YANG Lin ZHAO Xiang-Hua ZHOU Hong-Ping WU Jie-Ying YANG Jia-Xiang SHAO Guo-Quan CHENG Le-Hua TIAN Yu-Peng 《结构化学》2008,27(2)
A novel bis(β-diketonate) derivate, 3,6-bis(4,4,4-trifluorobutane-1,3-dione)-9-n- butylcarbazole 1, was synthesized and structurally characterized by single-crystal X-ray diffrac- tion. The crystal belongs to the monoclinic system, space group P21/c with a = 10.961(6), b = 22.942(13), c = 9.408(6) , α = 90, β = 109.663(9), γ = 90o, V = 2228(2) 3, Z = 4, Dc = 1.489 g/cm3, C24H19F6NO4, Mr = 499.40, F(000) = 1024 and μ = 0.134 mm–1. The structure was refined to the final R = 0.0699 and wR = 0.1627 for 3744 independent reflections (Rint = 0.1288) and 1349 observed reflections (I > 2σ(I)). Compound 1 consists of carbazole unit and two terminal diketonate groups, in which carbazole and its two adjacent diketonate rings are almost coplanar. Moreover, compound 1 was characterized with IR, elemental analysis, 1H NMR, MS, electronic absorption, and single-photon fluorescence. 相似文献
36.
Tatiana M. Pessanha Waldemir J. Paschoalino Patricia B. Deroco Sergio Kogikoski Jr Ana C. M. De Moraes Cecilia de Carvalho Castro Silva Lauro T. Kubota 《Electroanalysis》2022,34(4):692-700
The understanding of bidimensional materials dynamics and its electrolyte interface equilibrium, such as graphene oxide (GO), is critical for the development of a capacitive biosensing platform. The interfacial capacitance (Ci) of graphene-based materials may be tuned by experimental conditions such as pH optimization and cation size playing key roles at the enhancement of their capacitive properties allowing their application as novel capacitive biosensors. Here we reported a systematic study of Ci of multilayer GO films in different aqueous electrolytes employing electrochemical impedance spectroscopy for the application in a capacitive detection system. We demonstrated that the presence of ionizable oxygen-containing functional groups within multilayer GO film favors the interactions and the accumulation of cations in the structure of the electrodes enhancing the GO Ci in aqueous solutions, where at pH 7.0 (the best condition) the Ci was 340 μF mg−1 at −0.01 V vs Ag/AgCl. We also established that the hydrated cation radius affects the mobility and interaction with GO functional groups and it plays a critical role in the Ci, as demonstrated in the presence of different cations Na+=640 μF mg−1, Li+=575 μF mg−1 and TMA+=477 μF mg−1. As a proof-of-concept, the capacitive behaviour of GO was explored as biosensing platform for standard streptavidin-biotin systems. For this system, the Ci varied linearly with the log of the concentration of the targeting analyte in the range from 10 pg mL−1 to 100 ng mL−1, showing the promising applicability of capacitive GO based sensors for label-free biosensing. 相似文献
37.
38.
Michael Veith Hinka Hreleva-Carparrotti Volker Huch 《Journal of organometallic chemistry》2007,692(13):2784-2788
When the polycyclic alumosiloxane [Ph2SiO]8[AlO(OH)]4 is allowed to react with either cyclopentadienyl sodium in tetrahydrofuran or with dimethyl zinc in diethyl ether the organic ligands on the metal elements are eliminated as cyclopentadiene or methane and the metals are bonded to oxygen atoms in the alumosiloxane forming [Ph2SiO]8[AlO2(Na)]4 · 5(THF) or [Ph2SiO]8[AlO(OH)]2[AlO2]2[Zn(OH)]2 · 2(OEt2), respectively. X-ray structure determinations reveal that in the sodium derivative the original polycycle rests almost unchanged while in the zinc derivative the inner skeleton is rearranged. 相似文献
39.
Luisa Quijano Manuel Nogueras Miguel Melgarejo Adolfo Sánchez 《Monatshefte für Chemie / Chemical Monthly》1991,122(4):255-261
Summary Reactions of 6-glycopyranosylaminopyrimidin-4-ones1 a–d with malonic, methyl malonic and ethyl malonic acids are discussed in this paper. These reactions have been carried out in acetic anhydride at 100°C affording the 8-glycopyranosylpyrido[2,3-d]pyrimidin-4-ones2 a–d,3 c–d and the 5-acyl-6-glycopyranosylaminopyrimidin-6-ones4 a–d,5 a–d.
Reaktion von 6-Glycopyranosylaminopyrimidin-4-onen mit Malonsäuren. Synthese von 8-Glycopyranosylpyrido[2,3-d]pyrimidin-4-on-Dervaten
Zusammenfassung Es werden Reaktionen der 6-Glycopyranosylaminopyrimidin-4-one1 a–d mit Malonsäure, Methylmalonsäure und Ethylmalonsäure diskutiert. Die Reaktionen wurden in Essigsäureanhydrid bei 100°C ausgeführt und ergaben 8-Glycopyranosylpyrido[2,3-d]pyrimidin-4-one2 a–d,3 c–d und die 5-Acyl-6-glycopyranosylaminopyrimidin-6-one4 a–d und5 a–d.相似文献