Reactivity of 2-formylphenylboronic acid toward secondary aromatic amines in amination–reduction reactions

The synthesis of 2-(arylaminomethyl)phenylboronic acid via an amination–reduction reaction has been investigated within a model system comprising 2-formylphenylboronic acid and N-ethylaniline. Adoption of the appropriate reaction conditions influences the reactivity of 2-formylphenylboronic acid, enabling efficient synthesis of so-far unobtainable 2-(arylaminomethyl)phenylboronic compounds. The first crystal structure of the aromatic amine derivative has been determined and described

Homogenization of 7075 and 7049 Aluminium Alloys Intended for Extrusion Welding

During the extrusion of aluminum alloys profiles using porthole dies, the temperature of the material in the welding chamber is one of crucial parameters determining the quality of longitudinal welds. In order to extend the permissible temperature range, the billets intended for this process should be characterized by the maximum attainable solidus temperature. Within the present work, the homogenization of AlZnMgCu alloys DC-cast (Direct Chill-cast) billets was investigated, with the aim of solidus temperature maximization. Conditions of soaking and cooling stages were analyzed. The materials were homogenized in laboratory conditions, and the microstructural effects were evaluated on the basis of DSC (Differential Scanning Calorimetry) tests and SEM/EDS (Scanning Electron Microscopy/Energy-Dispersive Spectroscopy) investigations. For all examined alloys, the unequilibrium low-melting microstructure components were dissolved during soaking, which led to the significant solidus temperature increase, in comparison to the as-cast state. The values within the range of 525–548 °C were obtained. In the case of alloy with highest Cu concentration, the application of two-step soaking was necessary. In order to take advantage of the high solidus temperature obtained after soaking, the cooling rate from homogenization must be controlled, and the effective cooling manner is strongly dependent on alloy composition. For high-Cu alloy, the solidus decreased, despite the fast cooling and the careful billets preheating being necessary

Synthesis and Influence of 3-Amino Benzoxaboroles Structure on Their Activity against Candida albicans

Benzoxaboroles emerged recently as molecules of high medicinal potential with Kerydin® (Tavaborole) and Eucrisa® (Crisaborole) currently in clinical practice as antifungal and anti-inflammatory drugs, respectively. Over a dozen of 3-amino benzoxaboroles, including Tavaborole’s derivatives, have been synthetized and characterized in terms of their activity against Candida albicans as a model pathogenic fungus. The studied compounds broaden considerably the structural diversity of reported benzoxaboroles, enabling determination of the influence of the introduction of a heterocyclic amine, a fluorine substituent as well as the formyl group on antifungal activity of those compounds. The determined zones of the growth inhibition of examined microorganism indicate high diffusion of majority of the studied compounds within the applied media as well as their reasonable activity. The Minimum Inhibitory Concentration (MIC) values show that the introduction of an amine substituent in position “3” of the benzoxaborole heterocyclic ring results in a considerable drop in activity in comparison with Tavaborole (AN2690) as well as unsubstituted benzoxaborole (AN2679). In all studied cases the presence of a fluorine substituent at position para to the boron atom results in lower MIC values (higher activity). Interestingly, introduction of a fluorine substituent in the more distant piperazine phenyl ring does not influence MIC values. As determined by X-ray studies, introduction of a formyl group in proximity of the boron atom results in a considerable change of the boronic group geometry. The presence of a formyl group next to the benzoxaborole unit is also detrimental for activity against Candida albicans

FEM Numerical and Experimental Study on Dimensional Accuracy of Tubes Extruded from 6082 and 7021 Aluminium Alloys

The extrusion of hollow profiles from hard-deformable AlZnMg alloys by using porthole dies encounters great technological difficulties in practice. High extrusion force accompanies the technological process, which is caused by high deformation resistance and high friction resistance in extrusion conditions. As a result of high thermo-mechanical loads affecting the die, a significant loss of dimensional accuracy of extruded profiles can be observed. The different projects of porthole dies for the extrusion of Ø50 × 2 mm tubes from the 7021 alloy were numerically calculated and then tested in industrial conditions by using a press of 25 MN capacity equipped with a container with a diameter of 7 inches (for 7021 alloy and 6082 alloy for comparison). New extrusion die 3 with modified bridge and mandrel geometry and a special radial–convex entry to the die opening was proposed. FEM was applied to analyse the metal flow during extrusion, geometrical stability of extruded tubes and the die deflection. The photogrammetric measuring method was used to evaluate dimensional accuracy of tubes extruded in different conditions and geometrical deviations in porthole dies elements, especially the bridges and the mandrels. Research revealed a high dimensional accuracy of tubes extruded from the 6082 alloy and from the 7021 alloy by using original extrusion die 3, while much higher dimensional deviations were noted for tubes extruded from the 7021 alloy by using extrusion dies 1 and 2, particularly in relation to the circularity, centricity and wall thickness