Catalytic C-phenylation of methyl acrylate with triphenylantimony(v) dicarboxylates

Triphenylantimony dicarboxylates Ph₃Sb(OAc)₂ and Ph₃Sb(O₂CEt)₂ are efficient C-phenylating agents for methyl acrylate. In the presence of the Pd(OAc)₂, Li₂PdCl₄ or Pd₂(dba)₃(CHCl₃) catalysts in MeCN at 50 °C, methyl cinnamate forms in 70—150% yield with respect to Sb^V. Copper(ii) salts do not increase the reaction yield.     

Catalytic system based on triphenylantimony and tert-butyl hydroperoxide for the Heck reaction

Triphenylantimony was used as an efficient agent for C-phenylation of methyl acrylate in the presence of Bu^tOOH (1 to 2 mol) and a palladium salt (PdCl₂, Li₂PdCl₄; 0.04 mol) in AcOH at 50 °C. The yield of methyl cinnamate is two moles per mole of the starting Ph₃Sb.     

New water-soluble (hydroxymethyl)triphosphine [(HOCH2)2PCH2CH2]2PCH2OH, a derived PdII(triphosphine) complex, and triphosphine trioxide

An aqueous solution of (hydroxymethyl)triphosphine [(HOCH₂)₂P(CH₂)₂]₂PCH₂OH (II) was synthesized in situ by treatment of the triphosphine H₂P(CH₂)₂PH(CH₂)₂PH₂ with formaldehyde. Addition of a CH₂Cl₂ solution of trans-PdCl₂(PhCN)₂ to an in situ aqueous solution of II resulted in the formation of a species thought to be [PdCl{[(HOCH₂)₂P(CH₂)₂]₂PCH₂OH}]⁺Cl⁻. Attempts to isolate the complex were unsuccessful because of conversion to material containing small amounts of phosphine oxide(s) formed via a redox reaction involving water. The triphosphine trioxide [(HOCH₂)₂P(O)(CH₂)₂]₂P(O)CH₂OH was readily isolated from an in situ solution of II by treatment with aqueous H₂O₂.     

On estimation of delay location

Assume that we observe a stationary Gaussian process X(t), \({t \in [-r, T]}\) , which satisfies the affine stochastic delay differential equation

$d X(t) = \int\limits_{[-r,0]}X(t+u)\, a_\vartheta (du)\,dt +dW(t), \quad t\ge 0,$

where W(t), t ≥ 0, is a standard Wiener process independent of X(t), \({t\in [-r, 0]}\) , and \({a_\vartheta}\) is a finite signed measure on [?r, 0], \({\vartheta\in\Theta}\) . The parameter \({\vartheta}\) is unknown and has to be estimated based on the observation. In this paper we consider the case where \({\Theta=(\vartheta_0,\vartheta_1)}\) , \({-\infty\,<\,\vartheta_0 <0 \,<\,\vartheta_1\,<\,\infty}\) , and the measures \({a_\vartheta}\) are of the form

$a_\vartheta = a+b_\vartheta-b,$

where a and b are finite signed measure on [?r, 0] and \({b_\vartheta}\) is the translate of b by \({\vartheta}\) . We study the limit behaviour of the normalized likelihoods

$Z_{T,\vartheta}(u) = \frac{dP_T^{\vartheta+\delta_T u}}{dP_T^\vartheta}$

as T→ ∞, where \({P_T^\vartheta}\) is the distribution of the observation if the true value of the parameter is \({\vartheta}\) . A necessary and sufficient condition for the existence of a rescaling function δ _T such that \({Z_{T,\vartheta}(u)}\) converges in distribution to an appropriate nondegenerate limiting function \({Z_{\vartheta}(u)}\) is found. It turns out that then the limiting function \({Z_{\vartheta}(u)}\) is of the form

$Z_\vartheta(u)=\exp\left(B^H(u) - E[B^H(u)]^2/2\right),$

where \({H\in[1/2,1]}\) and B ^H (u), \({u\in\mathbb{R}}\) , is a fractional Brownian motion with index H, and δ _T  = T ^?1/(2H) ?(T) with a slowly varying function ?. Every \({H\in[1/2,1]}\) may occur in this framework. As a consequence, the asymptotic behaviour of maximum likelihood and Bayes estimators is found.

     

Numerical simulation and visualization of vortical structure transformation in the flow past a sphere at an increasing degree of stratification

Based on numerical simulation and visualization, the vortex structure of the flow past a sphere moving uniformly and horizontally in a linearly (density) stratified viscous fluid with an increasing degree of stratification (with the internal Froude number Fr decreasing from infinity to 0.005) at Re = 100 is analyzed in detail for the first time. The classification of the flow regimes is refined. The direct numerical simulation is based on the method of splitting with respect to physical factors (MERANZH) with an explicit hybrid finite-difference scheme, which is second-order accurate in space, monotone, and has a minimal numerical viscosity and dispersion.     

Study of the Reactions of Fullerene С60 with the Palladium-Containing Clusters of Molybdenum {Mo3PdS4} by Spectroscopic and Calculation Methods

Russian Journal of Coordination Chemistry - The fabrication of hybrid materials combining the physicochemical properties of various classes is a complicated but promising trend for the development...     

Binuclear Oxidovanadium(IV) Complex with the Bridging Chloranilate Ligand: Synthesis and Magnetic Properties

Russian Journal of Coordination Chemistry - The binuclear oxidovanadium(IV) complex [VO(Dbbpy)Cl(Ca)Cl(Dbbpy)VO] (I) is synthesized by the reaction of [VO(Dbbpy)(H2O)Cl2] (Dbbpy is...     

The electron structure of oxygen-containing iron

The magnetic susceptibility of oxygen-containing iron is investigated. The electron characteristics are calculated from thex (T) curves. It is shown that oxygen has a considerable effect on the electron properties of iron.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 43–46, March, 1984.