A convenient synthesis and spatial structure of 2-aryl-2-oxo-2-phenylbenzo[e]-1,4,2-oxazaphosphinanes

Phosphorylation of 2-arylideneaminophenol with dichlorophenylphosphine in the presence of triethylamine and subsequent treatment with water led to stereoisomeric derivatives of 3-aryl-2-oxo-2-phenylbenzo[e]-1,4,2-oxazaphosphinanes, which were separated by column chromatography to the individual diastereomers. The structure of stereoisomers was established by NMR spectroscopy and X-ray crystallography.     

Mathematical modeling of matter distribution in a circular cell ensemble

In this paper, a mathematical model describing substance transport in a circular cell ensemble is considered. The model is represented by an autonomous system of equations. With a parameter continuation model, it is shown that the stationary solutions may have various symmetry types represented by closed curves. The periodic solutions have the same property, where the components differ from each other by a simple shift.     

Conjugate heat transfer on a non-isothermal rotating disc

A derivation of the conjugation criterion for a rotating disc is reported. Characteristics of conjugate heat transfer on a single disc and in a cavity formed by two discs, one rotating and the other stationary, are analysed.     

1-Bromo-2-trifluoroacetylcyclobutenes as novel building blocks for the construction of trifluoromethyl substituted heterocycles. Part 3: Synthesis of trifluoromethylsubstituted pyridines, condensed with cyclobutene moieties

This paper describes a general synthetic approach to 3-cyano-4-trifluoromethylpyridines fused with cyclobutene rings with variable spiro conjunctions. The reaction of various 1-bromo-2-trifluoroacetylcyclobutenes with ammonia results in the substitution of bromine with an NH₂ group leading to corresponding enaminoketones in high yields, which, in turn, form the target pyridines by treatment with diethyl ethoxymethylencyanophosphonate in the presence of sodium hydride.     

Numerical simulations of cessation flows of a Bingham plastic with the augmented Lagrangian method

The augmented Lagrangian/Uzawa method has been used to study benchmark one-dimensional cessation flow problems of a Bingham fluid, such as the plane Couette flow, and the plane, round, and annular Poiseuille flows. The calculated stopping times agree well with available theoretical upper bounds for the whole range of Bingham numbers and with previous numerical results. The applied method allows for easy determination of the yielded and unyielded regions. The evolution of the rigid zones in these unsteady flows is presented. It is demonstrated that the appearance of an unyielded zone near the wall occurs for any non-zero Bingham number not only in the case of a round tube but also in the case of an annular tube of small radii ratio. The advantages of using the present method instead of regularizing the constitutive equation are also discussed.     

Selective amidoalkylation of cyclic enamino ketones with N-acyliminium salts of 3,4-dihydroisoquinolines

A series of cyclic enaminoketones were selectively amidoalkylated at the α-carbon in reactions with acyliminium reagents derived from 3,4-dihydroisoquinolines.     

Concerning the interconnections of some parameters of self-organizing oxyhydrate gels and their experimental determination

The appearance of a pulsating current in the elongated cell filled with the zirconium oxyhydrate gel under short-circuited electrodes and constant mixing was shown. The pulsating character of the current is expressed in the form of current splashes. The reason for the appearance of current splashes is the self-organization of the gel with time; to be more exact, the reason is the constant conformational reorganization of the oxyhydrate matrix. When magnetic field acts on the zirconium oxyhydrate gel, increases in both the current values and the current splashes are observed. The increase of the gel particle sizes in a magnetic field is detected. Thus, it is of interest to consider the connection between the period of appearance of current splashes, splashes amplitudes and the sizes of gel aggregate regions.

In this regard, it is important to find out the connection between the parameters of the self-organizing gel cell. We suppose that:

1. In the process of self-organizing, the concentration of monomers forming the matrix in a gel area may change with time.

2. Solution of the task is independent of time. Generally speaking, it is possible to find a time-dependant solution of the task, but it is hardly worth doing.