نتایج جستجو برای: nucleophilicity
تعداد نتایج: 348 فیلتر نتایج به سال:
Rate and equilibrium constants for the reactions of pyridines with donor-substituted benzhydrylium ions have been determined spectrophotometrically. The correlation equation log k(20 degrees C)=s(N+E), in which s and N are nucleophile-specific parameters and E is an electrophile-specific parameter, has been used to determine the nucleophilicity parameters of various pyridines in CH(2)Cl(2) and ...
Correlation of the solvent effects through application of the extended Grunwald-Winstein equation to the solvolysis of isopropyl chlorothioformate results in a sensitivity value of 0.38 towards changes in solvent nucleophilicity (l) and a sensitivity value of 0.72 towards changes in solvent ionizing power (m). This tangible l value coupled with the negative entropies of activation observed indi...
The efficient separation of ilmenite is a difficult problem in minerals flotation. For this issue, α-aminooctyl phosphinic acid (APA) was developed as selective collector to separate ilmenite. flotation test result showed that APA more for improving recovery compared with octylphosphonic (OPA). Adsorption, ZETA and FTIR measurements proved the chemical interaction between surface stronger than ...
Based on the relationship between average local ionization energy Ī(r) and electron affinity Ā(r) with electronic Fukui functions, i.e., f−(r) f+(r), respectively, in this paper, we establish a connection nuclear functions beyond frontier molecular orbitals. As consequence of connection, obtain expressions interpreted as variation nucleophilicity or electrophilicity (weighted by orbital functio...
The structure, bonding and reactivity of 2-adamantylidene and its heavier group-14 analogues, 2X (X10H14, X = C-Sn), have been studied at the M06/def2-TZVPP//BP86/def2-TZVPP level of theory. 2-Adamantylidene and its heavier analogues, 2X, have a singlet ground state, where the carbene and silylene bridges in 2C and 2Si are bent similarly to the foiled-type carbenes. The bending of the carbene a...
The binuclear zinc(II) complex, [Zn2(HPTP)(CH3COO)]2+ was found highly active to cleave DNA (double-strand super-coiled DNA, pBR322 and phix174) in the presence of hydrogen peroxide. However, no TBARS (2-thiobarbituric acid reactive substance) formation was detected in a solution containing 2-deoxyribose (or 2'-deoxyguanosine, etc); where (HPTP) represents N,N,N'-N'-tetrakis(2-pyridylmethyl)-1,...
Second-order rate constants (k(Nu)) have been measured for the addition of amines to ketenes 4-6 in acetonitrile solution by the laser flash photolysis technique. These ketenes are formed from a photochemical Wolff rearrangement of diazoketones 1-3, respectively. For all diazoketones studied, the presence of amines as nucleophiles in the reaction medium results in the formation of an intermedia...
Four different selendiazole compounds were handled by computational chemistry methods. Compounds 1,2,3-selendiazole, 1,2,5-selendiazole, 1,2,4-selendiazole and 1,3,4-selendiazole optimized at the B3LYP/6-31G(d) level. Structural parameters examined. In structural determination, IR NMR techniques, which are spectroscopic methods, applied. Quantum chemical giving global properties such as highest...
Palladium-catalyzed oxidative cyclization of alkenols provides a convenient entry into cyclic ethers but typically proceeds with little or no diastereoselectivity for cyclization of trisubstituted olefins to form tetrahydrofurans due to the similar energies of competing 5-membered transition-state conformations. Herein, a new variant of this reaction has been developed in which a PdCl2/1,4-benz...
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