New straightforward route for the synthesis of some 1‐oxa‐2‐silacyclopentane derivatives

Tris(dimethylsilyl)methyl lithium, (HSiMe₂)₃CLi, reacts with allyl, phenyl, benzyl, n‐propyl and n‐butyl glycidyl ethers in THF at ‐5 °C to give 1‐oxa‐2‐silacyclopentane derivatives. It seems that ring closure is facilitated by conversion of the Si? H bond into an Si? O bond. Glycidyl methacrylate (GM) random copolymers with 4‐methyl‐ and 4‐methoxy styrene, synthesized by solution free radical polymerization at 70 (±1) °C with α,α‐azobis(isobutyronitrile) (AIBN) as initiator, contained pendant epoxide functions. Treatment of these with (HSiMe₂)₃CLi did not lead to intramolecular nucleophilic attack as found for simple epoxides.     

Study of the reaction of 1,1-bis(trimethylsilyl)-2-phenylethylene with some acyl chlorides in the presence of AlCl3

1,1-Bis(trimethylsilyl)-2-phenylethylene (1), which has been synthesized from the Peterson reaction between (Me₃Si)₃CLi and benzaldehyde, reacts with various acyl chlorides (RCOCl, R = Me, Et, iso-Pr, n-Bu, iso-Bu, iso-C₅H₁₁, PhCH₂, PhCH₂CH₂) in the presence of AlCl₃ to give -silyl-,β-unsaturated enones 3a–3h with high E stereoselectivity along with trans-,β-unsaturated ketones 4a–4h. The enones 3 can be partially converted into the ketones 4 with an excess of AlCl₃. Reaction of 1 with RCOCl, (R = Ph, CH₃CH=CH) afforded only the ketones 4. Yields were dependent on time and the amounts of AlCl₃ used.     

Controlling chaos based on a novel intelligent integral terminal sliding mode control in a rod-type plasma torch

An integral terminal sliding mode controller is proposed in order to control chaos in a rod-type plasma torch system.In this method, a new sliding surface is defined based on a combination of the conventional sliding surface in terminal sliding mode control and a nonlinear function of the integral of the system states. It is assumed that the dynamics of a chaotic system are unknown and also the system is exposed to disturbance and unstructured uncertainty. To achieve a chattering-free and high-speed response for such an unknown system, an adaptive neuro-fuzzy inference system is utilized in the next step to approximate the unknown part of the nonlinear dynamics. Then, the proposed integral terminal sliding mode controller stabilizes the approximated system based on Lyapunov's stability theory. In addition, a Bee algorithm is used to select the coefficients of integral terminal sliding mode controller to improve the performance of the proposed method. Simulation results demonstrate the improvement in the response speed, chattering rejection, transient response,and robustness against uncertainties.     

Characterization of Primary Action Mode of Eight Essential Oils and Evaluation of Their Antibacterial Effect against Extended-Spectrum β-Lactamase (ESBL)-Producing Escherichia coli Inoculated in Turkey Meat

The current study aims to evaluate the antimicrobial activity of eight essential oils (EOs) against multidrug-resistant Escherichia coli strains, producing extended-spectrum β-lactamase (ESBL) enzymes and isolated from foods. Disc-diffusion assay showed that the inhibition diameters generated by EOs varied significantly among the tested EOs and strains. In fact, EOs extracted from Thymus capitaus, Eucalyptus camaldulensis, Trachyspermum ammi and Mentha pulegium exerted an important antimicrobial effect against tested strains, with the diameters of inhibition zones varied between 20 and 27 mm. Moreover, minimal inhibition and bactericidal concentration (MIC and MBC) values demonstrated that T. capitatus EOs generate the most important inhibitory effect against E. coli strains, with MIC values ranging from 0.02 to 0.78%. Concerning the mode of action of T. capitatus EO, the obtained data showed that treatment with this EO at its MIC reduced the viability of E. coli strains, their tolerance to NaCl and promoted the loss of 260-nm-absorbing material. In addition, in the presence of T. capitatus EO, cells became disproportionately sensitive to subsequent autolysis. Moreover, the inhibitory effect of T. capitatus was evaluated against two E. coli strains, experimentally inoculated (10⁵ CFU/g) in minced turkey meat, in the presence of two different concentrations of EO (MIC and 2 × MIC), and stored for 15 days. In both samples, EO exerted a bacteriostatic effect in the presence of concentrations equal to MIC. Interestingly, at 2 × CMI concentration, the bactericidal activity was pronounced after 15 days of storage. Our results highlighted that the use of essential oils, specially of T. capitatus, to inhibit or prevent the growth of extended-spectrum β-lactamase (ESBL)-producing E. coli in food, may be a promising alternative to chemicals.     

Novel Route for the Synthesis of 2-Arylquinazolinones Using Magnetic Nanocomposite of Multiwalled Carbon Nanotube

Russian Journal of Organic Chemistry - A series of 2-aryl-2,3-dihydroquinazolin-4(1H)-ones have been synthesized in excellent yields and short reaction time by one-pot reaction of...     

Modeling electrochemical surface responses for PANI bronze corrosion protection

Plackett–Burman experimental design was carried out in order to optimize the experimental conditions of polyaniline (PANI) electrodeposition for Cu10Sn bronze alloy corrosion protection in neutral aerated aqueous 0.5 M chloride medium. Seven factors including scan rate, aniline concentration, hydroxyl ions concentration, cycle number, nature of solvent, starting potential, and final potential for the cyclic voltammetry study were considered. The experimental responses were Ecorr, βa, βc, B, Jcorr, Rp, the percentage of protection efficiency and the coatings porosities. A linear mathematical model was applied to estimate the coefficients related to the different experimental responses. The significance of the different factors was evaluated through Pareto analysis. The optimum conditions for PANI electrodeposition were estimated and discussed. PANI coatings were concluded to offer protection efficiency higher than 90% for Cu10Sn bronze alloy. Copyright © 2016 John Wiley & Sons, Ltd.     

From imidates to vinyl-1,2,4-triazoles: Synthesis,mechanistic aspects and first issues of their reactivity

The reaction of variously substituted acylimidates with hydrazine derivatives represents an efficient and easy to set synthetic entry towards 5-vinyl-1,2,4-triazole derivatives. The construction of the triazole ring allows the installation of variety of substituent combination at the N(1), C(3) and C(5) positions of the five-membered heterocycle in good to high yields. The method reveals selective towards 5-vinyl-1,2,4-triazoles avoiding the potential formation of seven- and five-membered side-products as supported by theoretical calculations and NMR experiments. First lines of Pd-catalyzed arylation of the vinyl fragment towards 5-styryl-1,2,4-triazoles and Cu-catalyzed arylation at the N(1) site are finally described.     

Synthesis of silyl-protected terminal thioalkyne-substituted tetraaryl imidazoles: utilization of Ag–Fe/ZSM-5 bimetallic nanooxides for cyclocondensation of polysubstituted imidazoles

Research on Chemical Intermediates - An improved one-pot and ecofriendly approach to tri- and tetraaryl imidazoles through three- and four-component coupling reactions under neutral and...     

Synthesis of 5-(dimethylsilyl)pentylalkylferrocene-grafted HTPB (alkylFc-HTPB) via platinum-catalyzed hydrosilylation

In this work, at first alkylferrocene derivatives were synthesized according to procedure described in the literature. (5-Chloropentanoyl)ferrocene derivatives were prepared by Friedel–Crafts acylation of ferrocene and alkylferrocene derivatives with 5-chloropentanoyl chloride in dichloromethane, and AlCl₃ was used as catalyst. The corresponding 5-chloropentylferrocene derivatives were synthesized from reduction of these products by NaBH₄ in diglyme at 0 °C. Finally (5-alkylferrocenylpentyl)dimethylsilane was synthesized from reaction of 5-chloropentylferrocene derivatives with magnesium in THF and reaction of corresponding Grignard reagents with chlorodimethylsilane in 82–87% yields. ¹H and ¹³C NMR, FT-IR spectroscopy supported the predicted structure of the product. Nine samples of alkylferrocene-grafted hydroxyl-terminated polybutadiene (alkylFc-HTPB) derivatives, containing different percent of iron, were synthesized by hydrosilylation reaction of [5-(alkylferrocenyl)pentyl]dimethylsilane with hydroxy-terminated polybutadiene (HTPB), in the presence of catalytic amount of the hexachloroplatinic acid (Speier’s catalyst). FT-IR spectroscopy was utilized to follow the progress of the reaction, by monitoring the loss of the Si–H absorption at 2110 cm^?1, and the reaction was completed in 24 h. Some properties of resulting prepolymer like viscosity, glass transition temperature and iron percentage as important parameters in production of composite propellants were investigated. For example, the viscosity increased with increasing iron content because of the greater extent of ferrocene grafting in the polymer.