Mongia Saïd Zina

Hyperbranched cyclic and multicyclic poly(etherketone)s by polycondensation of isosorbide and isomannide with 2,6,4′-trifluorobenzophenone and 1,3,5-tris(4-fluorobenzoyl) benzene

1,3,5-Tris(4-fluorobenzoyl)benzene (TFBB) and 2,6,4′-trifluorobenzophenone (TFB) were polycondensed with isosorbide and isomanide. All polycondensations were performed in a mixture of dimethyl sulfoxide and toluene with potassium carbonate as promotor. Optimal concentration to avoid gelation was set at 0.06 mol L−1. The different cyclization tendencies on the basis of monomers conformations are discussed. In the TFB series, the feed ratio isosorbide/TFB was varied from 1.0:1.0 to 1.5:1.0. A majority of linear and hyperbranched species were identified as main reaction products by matrix-assisted laser desorption/ionization–time-of-flight mass spectrometry regardless of the diol with slight cyclization tendency for isomannide. When TFBB was polycondensed with isosorbide, the cyclization tendency was significantly improved. The products obtained at a feed ratio of 1.41/1.0 and 1.51/1.0 were rich in cyclic and multicyclic species. More interesting results were obtained from the polycondensation of TFBB and isomannide, giving rise majoritarily to cyclic, bicyclic, and multicyclic species. Differential scanning calorimetric measurements indicated high glass transition temperature (around 200°C).

Biosourced 1,2,3-triazolium ionic liquids derived from isosorbide

Two series of 1,2,3-triazolium chiral ionic liquid (CIL) stereoisomers are synthesized from isosorbide by combining the robust attributes of the copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC), alkylation of the resulting 1,2,3-triazoles by methyl iodide and further anion metathesis with different fluorinated salts. These novel biosourced CILs are characterized in details by 1H and 13C NMR spectroscopy, high-resolution mass spectrometry (ESI-HRMS), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and broadband dielectric spectroscopy (BDS). The effect of stereochemistry on their physical, thermal and ion conducting properties is discussed. Markedly, it is demonstrated for the first time that stereochemistry can drastically influence ionic conductivity by several orders of magnitude.

Fatty Acids Composition and Antibacterial Activity of Aristolochia longa L. and Bryonia dioïca Jacq. Growing Wild in Tunisia

The composition of the fatty acids of the roots and aerial parts of Aritolochia longa (Aristolacheae) and Bryonia dioïca (Cucurbutaceae) was analyzed by gas chromatography (GC-FID) and gas chromatography-mass spectrometry (GC-MS). The oils extracted from the aerial parts of both species were rich in polyunsaturated fatty acids with the essential linolenic and linoleic acids being the most prominent compounds. Oleic and linoleic acids were the majors fatty acids in the roots of both species. Whatever the plant part analyzed and the species, the saturated fatty acids were predominantly composed of palmitic and stearic acids. The antibacterial activity, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the lipid extracts were determined against a panel of five bacterial strains. The results showed that the sensitivity to the lipid extracts was different for the test bacterial strains, and the susceptibility of gram positive bacteria was found to be greater than gram negative bacteria. The antibacterial activity of the root lipid extracts was particularly important against Enterococcus feacium (CMI value of 125 µg/mL; CMB values > 250 µg/mL) and Streptococcus agalactiae (CMI value of 125 µg/mL; CMB values 250 µg/mL for A. longa roots). These results indicate that A. longa and B. dioïca could be considered as good sources of essential fatty acids which can act as natural antibacterial agents.

Oxidation of Methane to Methanol over Single Site Palladium Oxide Species on Silica: A Mechanistic view from DFT

A theoretical analysis was carried out on the mechanism of methane oxidation to methanol occurring on single site palladium oxide species [PdO]2+ supported on a model of Al-MCM-41 silica. Both 6- and 8-membered ring structures were considered to represent the support. The energy profile for each elementary reaction was determined from density functional theory calculations with the OPBE functional. The calculated overall activation energies are close to the experimental values. Our calculations confirm that spin inversion can play a significant role in decreasing the barrier heights for the pathways. Indeed, in this type of reactions we could show a crossing between singlet and triplet reaction paths. We showed that the mechanism for the C-H bond cleavage and for the formation of methanol has a radical nature. According to our results, the [PdO]2+ species located on a 8-membered ring of silica is more active than that deposited on a 6-membered ring. The calculated activation energies to cleave the methane C-H bond are 35 and 84 kJ/mol for the radical and ionic pathways, respectively. The activation barrier and the transition state geometry of this H-abstraction step are directly correlated with the optimal angle at which the substrate should approach the [Pd═O]2+ moiety, with the elongation of the Pd-Ooxo bond and finally with the energy of the π* acceptor orbital.

New biosourced AA and AB monomers from 1,4:3,6-dianhydrohexitols, Isosorbide, Isomannide, and Isoidide

Abstract In the present work, we propose the synthesis of a new family of sugar derived 1,4:3,6-dianhydrohexitol based AA/AB-type monomers. Unprecedented diacids based on Isomannide and Isoidide were elaborated with high yields and showed interestingly high melting point ranges (240–375 °C). Optimization of reaction conditions (temperature, time of reaction, and reactant ratios) has been investigated to synthesize the key intermediate of a set of AB monomers with acid, ester, and acid chloride functionalities. Isosorbide based ether benzoic acid AB monomer was polymerized and characterized by NMR and DSC techniques. The results show a semicrystalline behavior of the obtained polymer thanks to the controlled stereoregular arrangement of the AB starting monomer.

Synthesis and characterization of novel biosourced building blocks from isosorbide

Abstract New biosourced unprotected diols were prepared by acylation reaction of aminoalcohol based on 1,4:3,6-dianhydrosorbitol (Isosorbide Is) with several aliphatic and aromatic diacyl chlorides (sebacoyl, adipoyl, and terephthaloyl). Optimization of reaction conditions (solvent, base nature, and addition mode) has been investigated with protected alcohols. The use of hindered bases was needful to ensure the selectivity of the addition reaction when starting from unprotected aminoalcohol, and selectively led to bis amides products with good yields. 1D and 2D NMR techniques were used to ascertain the structures of the unprecedented monomers. These novel building blocks were successfully polymerized using succinic and terephthalic spacers and studied by NMR and DSC techniques.

Catalytic conversion of N2O over palladium catalysts based on dealuminated faujasite

Dealumination of the faujasite support was realised using a hydrothermal treatment at different temperatures (625 – 700°C). Then palladium catalysts were prepared by an ion exchange method. The prepared catalysts exhibited a high and constant activity up to 100% for N2O conversion. This performance was dependent on certain parameters, such as a high Si/Al ratio, the structural properties of the zeolitic support, and the metal function provided by the palladium. In addition, it is considered that the active sites in the reaction, which are suspected to be PdO, are influenced by the acidic properties of the support.

Synthesis and characterization of novel organosoluble biosourced poly(ester imide)s based on 1,4:3,6 -dianhydrohexitols suited for adhesives applications

Abstract A new series of poly(ester imide)s were prepared from the polycondensation of isosorbide and a series of synthesized diacyl chloride monomers based on a reaction between 1,2,4-Benzenetricarboxylic anhydride (TMA) and various diamines. The structures of the resulting polymers were confirmed by Fourier transform infrared spectroscopy (FTIR) and 13C NMR spectra. Inherent viscosities and size exclusion chromatography (SEC) measurements proved the formation of high molecular weight poly(ester imide)s. The thermogravimetric analysis (TGA) showed deterioration temperature in the range of 221–400 °C indicating a good thermal stability. The differential scanning calorimetry (DSC) measurements revealed high glass transition temperature in the range of 67–185 °C. Wide angle X-ray diffraction measurements showed that the studied poly(ester imide)s were semi-crystalline. Most of the synthesized poly(ester imide) exhibited a good adhesion ability and tensile strength values comparable to analogous polymers.

New biosourced chiral molecularly imprinted polymer: Synthesis, characterization, and evaluation of the recognition capacity of methyltestosterone

New biosourced chiral cross‐linkers were reported for the first time in the synthesis of methyltestosterone (MT) chiral molecularly imprinted polymers (cMIPs). Isosorbide and isomannide, known as 1,4:3,6‐dianhydrohexitols, were selected as starting diols. The cMIPs were synthesized following a noncovalent approach via thermal radical polymerization and monitored by Raman spectroscopy. These cross‐linkers were fully characterized by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and high‐resolution mass spectrometry. The cross‐polarization magic angle spinning 13C NMR, Fourier transform infrared spectroscopy, scanning electron microscopy, and specific surface areas following the Brunauer‐Emmett‐Teller (BET) method were used to characterize the cMIPs. The effect of stereochemistry of cross‐linkers on the reactivity of polymerization, morphology, and adsorption‐recognition properties of the MIP was evaluated. The results showed that the cMIP exhibited an obvious improvement in terms of rebinding capacity for MT as compared with the nonimprinted polymer (NIP).