α‐Arylation of Carbonyl Compounds through Oxidative C−C Bond Activation

A synthetically useful approach for the direct α‐arylation of carbonyl compounds through a novel oxidative C?C bond activation is reported. This mechanistically unusual process relies on a 1,2‐aryl shift and results in all‐carbon quaternary centers. The transformation displays broad functional‐group tolerance and can in principle also be applied as an asymmetric variant.     

Optimization Strategies Based on Sequential Quadratic Programming Applied for a Fermentation Process for Butanol Production

In this work, the mathematical optimization of a continuous flash fermentation process for the production of biobutanol was studied. The process consists of three interconnected units, as follows: fermentor, cell-retention system (tangential microfiltration), and vacuum flash vessel (responsible for the continuous recovery of butanol from the broth). The objective of the optimization was to maximize butanol productivity for a desired substrate conversion. Two strategies were compared for the optimization of the process. In one of them, the process was represented by a deterministic model with kinetic parameters determined experimentally and, in the other, by a statistical model obtained using the factorial design technique combined with simulation. For both strategies, the problem was written as a nonlinear programming problem and was solved with the sequential quadratic programming technique. The results showed that despite the very similar solutions obtained with both strategies, the problems found with the strategy using the deterministic model, such as lack of convergence and high computational time, make the use of the optimization strategy with the statistical model, which showed to be robust and fast, more suitable for the flash fermentation process, being recommended for real-time applications coupling optimization and control.     

Limits of Multiplicities in Excellent Filtrations and Tensor Product Decompositions for Affine Kac-Moody Algebras

We express the multiplicities of the irreducible summands of certain tensor products of irreducible integrable modules for an affine Kac-Moody algebra over a simply laced Lie algebra as sums of multiplicities in appropriate excellent filtrations (Demazure flags). As an application, we obtain expressions for the outer multiplicities of tensor products of two fundamental modules for \(\widehat {\mathfrak {sl}}_{2}\) in terms of partitions with bounded parts, which subsequently lead to certain partition identities.     

PANI–WO3·2H2O Nanocomposite: Phase Interaction and Evaluation of Electronic Properties by Combined Experimental Techniques and Ab-Initio Calculation

The development of conjugated polymer-based nanocomposites by adding metallic particles into the polymerization medium allows the proposition of novel materials presenting improved electrical and optical properties. Polyaniline Emeraldine-salt form (ES–PANI) has been extensively studied due to its controllable electrical conductivity and oxidation states. On the other hand, tungsten oxide (WO₃) and its di-hydrated phases, such as WO₃·2H₂O, have been reported as important materials in photocatalysis and sensors. Herein, the WO₃·2H₂O phase was directly obtained during the in-situ polymerization of aniline hydrochloride from metallic tungsten (W), allowing the formation of hybrid nanocomposites based on its full oxidation into WO₃·2H₂O. The developed ES–PANI–WO₃·2H₂O nanocomposites were successfully characterized using experimental techniques combined with Density Functional Theory (DFT). The formation of WO₃·2H₂O was clearly verified after two hours of synthesis (PW₂ nanocomposite), allowing the confirmation of purely physical interaction between matrix and reinforcement. As a result, increased electrical conductivity was verified in the PW₂ nanocomposite: the DFT calculations revealed a charge transfer from the p-orbitals of the polymeric phase to the d-orbitals of the oxide phase, resulting in higher conductivity when compared to the pure ES–PANI.     

Hydrogenation of carbon dioxide: From waste to value

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One-pot synthesis of telluroketene acetals and haloketene acetals using sp2 geminated hetero organobismetallic intermediates

A novel one-pot synthesis of 1,1-dihalo-1-alkenes and 1,1-bis(butyltelluro)-1-alkenes was developed from hydrozirconation of alkynylzinc bromide with Cp₂Zr(H)Cl and subsequent capture of the Zn/Zr 1,1-heterodimetallo-1-alkene intermediates with halogen and tellurium electrophiles. These protocols, which include multiple reactions in a one-pot procedure, allow the preparation of the potentially useful haloketene acetals and telluroketene acetals from terminal alkynes, under mild conditions and in a good yield.     

A Simple Synthesis of (R)(S)(E)-3,7-Dimethyl-2-octene-1,8-dioc Acid,a Copulation Release Pheromone Component of the Azuki Bean Weevil

(R)(S)(E)-3,7-dimethyl-2-octene-1,8-dioic acid, (R)(S)(E)-1, also named callosobruchusic acid, has been synthetized in five steps using a simple reaction sequence based on the zirconium-catalyzed methylalumination of commercially available 4-pentyn-1-ol, 2a, or its O-tert-butyldimethylsilyl ether, 2b.     

Evaluation of activity of a commercial amylase under ultrasound-assisted irradiation

The main objective of this work was to evaluate the effects of ultrasound irradiation on the activity of a commercial amylase. A central composite design was carried out to assess the effects of temperature and pH on the enzyme activity in the presence and absence of ultrasound irradiation. The activation energy, the influence of treatment time as well as the substrate concentration on enzyme activity were also determined in the presence and absence of ultrasound irradiation. The results demonstrated that the effect of temperature was less pronounced in the presence of ultrasound, resulting in a decreasing of about 80% in the activation energy in comparison with the value obtained in the absence. The enzyme showed activities about 3 times higher for temperatures up to 40 °C in the presence of ultrasound. The pH negatively affected the activity in the presence of ultrasound, whereas in the absence a positive effect was verified. The ultrasound irradiation is a promising technology to be used in enzymatic reaction due to its positive effects on enzyme activity.