نتایج جستجو برای: nucleophilicity
تعداد نتایج: 348 فیلتر نتایج به سال:
The specific rates of solvolysis of ethyl fluoroformate have been measured at 24.2 degrees C in 21 pure and binary solvents. These give a satisfactory correlation over the full range of solvents when the extended Grunwald-Winstein equation is applied. The sensitivities to changes in the N(T) solvent nucleophilicity scale and the Y(Cl) solvent ionizing power scale, and the k(F)/k(Cl) values are ...
Thioglycosidic bonds are of utmost importance in biomolecules as their incorporation led to more stable glycomimetics with potential drug activities. Until now only chemical methods were available for their incorporation into glycofuranosyl conjugates. Herein, we wish to describe the use of the first furanothioglycoligase for the preparation of a great variety of thioaryl derivatives with moder...
generated by activation of the corresponding dialkyl compounds with B(C6F5)3 are active homogeneous catalysts for olefin polymerization. Weakly coordinating anions are required to minimize the ion-pairing interactions, which are crucial in determining the properties of the resulting polymeric materials and the characteristics of the polymerization processes. These counteranions frequently conta...
The base-switched annuloselectivity, namely [2 + 2] and [2 + 2 + 2] selectivity, in the reactions of ethyl malonyl chloride and imines is successfully realized. In the presence of the weak nucleophilic base 2-chloropyridine, the reactions deliver ethyl trans-β-lactam-3-carboxylates as the exclusive [2 + 2] products in up to 93% yields, while with the strong nucleophilic N-methylimidazole as the...
The specific rates of solvolysis (including those obtained from the literature) of isopropenyl chloroformate (1) are analyzed using the extended Grunwald-Winstein equation, involving the N(T) scale of solvent nucleophilicity (S-methyldibenzothiophenium ion) combined with a Y(Cl) scale based on 1-adamantyl chloride solvolysis. A similarity model approach, using phenyl chloroformate solvolyses fo...
Oxidative addition of cobaltoceniumdiazonium bis(hexafluoridophosphate) with (pseudo)halide aurates gave gold(III) complexes containing zwitterionic cobaltoceniumide as a ligand. Its selenium derivative, cobaltoceniumselenolate, was obtained by an electrophilic aromatic substitution reaction of iodocobaltocenium iodide with Na2 Se. Spectroscopic and structural data in combination with DFT calcu...
A series of mononuclear zinc thiolate complexes have been prepared and fully characterized. The reactions of the complexes with alkyl halides, leading to zinc halides and the corresponding thioethers, have been examined by kinetic methods. In toluene, the reactions obey a second-order rate law displaying activation parameters consistent with a S(N)2 attack of the zinc-bound thiolate on the carb...
Specific rates of solvolysis at 25 degrees C for p-nitrophenyl chloroformate (1) are analyzed using the extended (two-term) Grunwald-Winstein equation. For 39 solvents, the sensitivities (l = 1.68+/-0.06 and m = 0.46+/-0.04) towards changes in solvent nucleophilicity (l) and solvent ionizing power (m) obtained, are similar to those previously observed for phenyl chloroformate (2) and p-methoxyp...
Palladation of C2-protected diimidazolium salts with Pd(OAc)2 afforded complexes comprising C4-bound N-heterocyclic dicarbene ligands. The reactivity of these complexes towards Lewis acids (AgBF4, AgOAc) and Brønsted acids (H2SO4, H3PO4, HOAc) revealed that abnormal C4 bonding of the carbenes markedly increases the nucleophilicity of the coordinated palladium center as compared to C2 bonding. D...
Remarkable site-specificity in the resonant attachment of low energy electrons (LEEs) to molecular targets is proposed as an efficient method for inducing chemical reactivity on specific sites of molecules. The Coulomb interaction between the attached electron and the most polarizable molecular electrons localized on the attached site is the reason for site-specific chemical reactivity. The Cou...
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