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1.
N. A. Zvereva 《Journal of Structural Chemistry》2001,42(5):730-738
This paper reports on an ab initio (6-31G**) study of 1:1, 1:2, and 2:1 (H2O)
n
(HCl)
m
complexes. Stable configurations of the 1:2 and 2:1 (H2O)
n
(HCl)
m
complexes and their geometrical and energy characteristics were determined. The vibrational analysis of the complexes was carried out. The effect of hydrogen bonding due to S1S0 and T0T1 electronic excitations is considered. 相似文献
2.
DanMeiDAI YouChengLIU JingLI PeiWANG XuDongCHEN ThomasC.W.MAK 《中国化学快报》2004,15(3):353-356
1,1-Di-p-methoxyphenyl-2, 2-dinitroethylene reacts with 1-benzyl-1, 4-dihydronicotinamide (BNAH) in deaerated acetonitrile to give 1,1-di-p-methoxyphenyl-2, 2-dinitroethane,while 1,1-di-O-methoxyphenyl-2, 2-dinitroethylene fails to react with BNAH under the same conditions, which provides evidence for a concerted electron-hydrogen atom transfer mechanism. 相似文献
3.
本文讨论了A_(a_1),A_(a_2)-B_(b_1)B_(b_2)型缩聚反应的固化理论。给出了溶胶-凝胶分配公式、凝胶化条件、分布函数及适合固化全过程的高分子矩的循环公式和k次矩的解析表示式。 相似文献
4.
1 INTRODUCTIONDithioacetals[1 3]havedemonstratedtheirpotentialforthesynthesisofheterocy cles,therefore ,theirsynthesisandreactionshaveattractedmuchattention ,butverylittlehasbeenreportedabouttheoxidationofdithioacetals[4].Accordingtotheprevi ousreport,theoxid… 相似文献
5.
Yi Bo ZHOU Jun An MA Li Xin WANG Qi Lin ZHOU* State Key Laboratoratory Institute of Elemento-Organic Chemistry Nankai University Tianjin 《中国化学快报》2002,13(10)
During the last decade, 1-aminocyclopropanecarboxylic acid and its derivatives (ACCS) have attracted increasing attention of organic and bioorganic chemists due to their outstanding biological properties, ranging from antimicrobial, insecticidal, plant growth and fruit ripening controls, etc.1. Moreover, the three-membered carbocycle provides building blocks of unprecedented synthetic potential because it undergoes selective ring opening, ring enlargement or cycloaddition reactions2. The mo… 相似文献
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7.
Solubility of Oxygen in Some 1-1, 2-1, 1-2, and 2-2 Electrolytes as a Function of Concentration at 25°C 总被引:1,自引:0,他引:1
The solubility of oxygen has been measured in a number of electrolytes [(LiCl, KCl, RbCl, CsCl, NaF, NaBr, NaI, NaNO3, KBr, KI, KNO3, CaCl2, SrCl2, BaCl2, Li2SO4, K2SO4, Mn(NO3)3)] as a function of concentration at 25°C. The solubilities, mol (kg-H2O)–1, have been fitted to a function of the molality m (standard deviation < 3mol-kg–1)
where A and B are adjustable parameters and the activity coefficient of oxygen )O2) = [O2]0/[O2]. The limiting salting coefficient, k
S = (ln / m)m=0 = A, was determined for all salts. The salting coefficients for the chlorides and sodium salts showed a near linear correlation with the crystal molar volume V
cryst = 2.52 r
3. The salting coefficients determined from the Scaled Particle Theory were in reasonable agreement with the measured values. The activity coefficients of oxygen in the solutions have been interpreted using the Pitzer equation
where
is a parameter that accounts for the interaction of O2 with cations (c) and anions (a) with molalities m
a and m
c, and
accounts for interactions for O2 with the cation and anion pair (c-a). The
and
coefficients determined for the most of the ions are in reasonable agreement with the tabulations of Clegg and Brimblecombe. The values of
for most of the ions are a linear function of the electrostriction molar volume (Velect = V0 – V
cryst). 相似文献
8.
《合成化学》2004,(Z1)
During our synthesis of N-benzoyl-N'-aryl selenourea derivatives, we isolated the title compound. One of them was selected optically for the diffraction study. The crystal belongs to the Monoclinic space group P21/n, Mr = 353.27, a = 11.073(1)? , b = 5.745(1) ?, c = 24.356(5) ?, β = 92.10 (1) , V = 1548.3 (4) ?3, Z = 4, Dx=1.515 Mg/m3,λ(Mo Kα)=0.71073 ?,θ = 1.67-25,μ o = 2.428 mm-1 , T = 296 (2) K. View of the molecule showing the labeling of the non-H atoms are described as: The se… 相似文献
9.
申贵隽 《中国无机分析化学》2012,2(2)
氰化物是一种快速、剧毒的化合物,能够引起组织衰竭以至机体死亡。氰化物一旦污染环境及食用源,会严重危害人体健康,当吸入或口服较大剂量氰化物时,会引起“闪电式”骤死,中毒者在10~60S内突然发出尖叫随即昏倒,出现强直性与阵发性痉挛,2-3min后呼吸停止而死亡[1]。因此加强对氰化物检测是一项重要的安全检测指标,为此,建立准确、快速,特别是能用于现场操作的氰化物测定方法有重要意义。 相似文献
10.
Electrolytic conductivities of eight simple 11 electrolytes have been measured in dilute solutions of 2-cyanopyridine (2CNP) at 30°. Infinite dilution mobilities and association constants were calculated using the Fuoss-Hsia equation. With the exception of LiCF3SO3 all salts show very little association, consistent with the very high dielectric constant of 2CNP. The weak association which does occur is attributed to weak ion-solvent interactions. No evidence was found for triple ion formation. Conductivities of concentrated solutions of LiAsF6 in 2CNP increase slowly with concentration reaching a maximum at a concentration of around 0.65 mol-dm–3. These conductances are slightly lower than those in propylene carbonate which has a lower dielectric constant and a higher viscosity. Conductivities of concentrated LiAsF6 solutions in 2CNP mixtures with acetonitrile vary monotonically, consistent with solution viscosities, and show no sign of the maximum commonly observed in mixed organic solvents. 相似文献
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12.
Condensation of 2-methyl-1-pyrroline with chloroacetone or 3-chloro-2-butanone using LDA in THF afforded novel 2-(3-hydroxy-2-methyl-1-alkenyl)-1-pyrrolines via a peculiar reaction mechanism instead of the anticipated 2-(3-oxobutyl)-1-pyrrolines. The intermediacy of 2-(2,3-epoxy-2-methylalkyl)-1-pyrrolines in the latter transformation was demonstrated by immediate reductive epoxide ring opening utilizing lithium aluminium hydride in diethyl ether. Furthermore, 2-(3-oxobutyl)-1-pyrroline was prepared via an alternative approach through alkylation of 2-methyl-1-pyrroline with 3-chloro-2-(methoxymethyloxy)-1-propene using LDA in THF, followed by acid hydrolysis. Reduction of 2-(3-oxobutyl)-1-pyrroline by sodium borohydride in methanol afforded the corresponding 2-(3-hydroxybutyl)-1-pyrroline in good yield. 相似文献
13.
《中国化学》2002,(11)
CHAO ,Hui 12 35………………CHEN ,Ming De 1149…………CHEN ,Qing Hua 1340…………CHEN ,Wei 140 1………………CHEN ,Xiao Min 1139…………CHEN ,Xiao Ming 140 6………CHEN ,Zhen Chu 145 7………CHENG ,Jin Sheng 132 6………CHENG ,Peng 12 4 9……………DENG ,Guo Jun 1139…………DesMarteau ,D .D . 12 6 8………DING ,Kui Ling 130 0…………DING ,Yu 1415………………DU ,Chen X… 相似文献
14.
《Journal of solid state chemistry》1986,64(3):365-371
Members of the systems Co1−xRhxS2 (0 ≤ x ≤ 0.6) were prepared, and their crystallographic and magnetic properties studied. The observed ferromagnetic moments for compositions where x ≤ 0.2 indicate a ferromagnetic alignment between Co(3d7) and Rh(4d7) electrons. This is the first observation of localized behavior of 4d electrons in the pyrite structure. Members of the systems Co1−xRuxS2 (0 ≤ x ≤ 1) and Rh1−xRuxS2 (0.5 ≤ x ≤ 1) were also prepared and their crystallographic and magnetic properties studied. From comparison with the Co1−xRhxS2 system, it appears that the 4d electrons of Rh(4d7) are localized in the presence of Co(3d7) but are delocalized in the presence of Ru(4d6). The magnetic susceptibility of the Co1−xRuxS2 system is sensitive to the homogeneity of the products and indicates that Ru(4d6) behaves as a diamagnetic ion. 相似文献
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18.
Chen Jun Xu Haifeng Guo Ying Dai Jinghua Zhang Limin Liu Shilin Ma Xingxiao 《化学物理学报(中文版)》2001,14(4):389-396
Photodissociation dynamics of CS2+molecular ions has been investigated by (1+two-photon resonance technique. CS2+were prepared by (3+1) resonance-enhanced multi-photon ionization (REMPI) of CS2molecules at 483. 2nm. The photofragment S+excitati (PHOFEX) spectra were recorded by scanning another laser in the 424~482nm region, and we assigned essentially to CS2+(~A2Πu,3/2(v′=0~4)←~X2Πg,3/2(0,0,0)) and (~A2Πu,1/2(v′=0,4)←~X2Πg,1/2(0,0,0)) (herev′=v1′+(1/2)v2′) transitions. The S+production channel wpreliminarily attributed to, (i) one-photon excitation CS2+from the ground state~X2Πgto texcited state~A2Πu; (ii) vibronic coupling between the~A2Πustate and the high vibrational lev in the~X2Πgstate; (iii) second photon excitation from the coupling vibrational levels to the excied state~B2Σu+and dissociation to produce S++ CS via the repulsive4Σ-state through spin-orb interaction between the~B2Σu+and4Σ-states. 相似文献
19.
Li Guo Weicheng Zhang Ilia A. Guzei Lara C. Spencer Samuel H. Gellman 《Tetrahedron》2012,68(23):4413-4417
Oligomers containing both α- and γ-amino acid residues in a 1:1 alternating pattern have recently been shown by several research groups to adopt helical secondary structures. We have begun to explore the folding behavior of oligomers with different α-residue/γ-residue backbone patterns. Previously we reported that the γ-amino acids bearing a cyclohexyl constraint at the Cβ–Cγ bond and a variable side chain at Cα strongly promote a helical conformation containing 12-atom CO(i)?H–N(i+3) hydrogen bonds for 1:1 α:γ backbones. Here we report synthesis and crystallographic analysis of 2:1 and 1:2 α/γ-peptides that adopt CO(i)?H–N(i+3) hydrogen-bonded helical conformations. 相似文献
20.
Ohne Zusammenfassung 相似文献