История развития математических знаний

Isosorbide is a platform chemical of considerable importance for the future replacement of fossil resource-based products. Applications as monomers and building blocks for new polymers and functional materials, new organic solvents, for medical and pharmaceutical applications, and even as fuels or fuel additives are conceivable. The conversion of isosorbide to valuable derivatives by functionalization or substitution of the hydroxyl groups is difficult because of the different configurations of the 2- and 5-positions and the resulting different reactivity and steric hindrance of the two hydroxyl groups. Although a substantial amount of work has been published using exclusively the endo or exo derivatives isomannide and isoidide, respectively, as starting material, a considerable effort is still necessary to transfer and adapt these methods for the efficient conversion of isosorbide. This Minireview deals with all aspects of isosorbide chemistry, which includes its production by catalytic processes, special properties, and chemical transformations for its utilization in biogenic polymers and other applications of interest

Synthèse et caractérisation de nouveaux polymères à partir de l'isosorbide

Avec l'objectif de valoriser l'isosorbide et d'avoir accès à de nouveaux polyamides issus de dérivés de la biomasse, deux diamines (de type aniline et de type benzylamine) ont été synthétisées avec de bons rendements ( 70 % en deux étapes)par des réactions simples dans des conditions de catalyse par transfert de phase. Dans le cas de la diamine de type aniline, la méthode de polycondensation en solution dans la NMP avec des dichlorures d'acides aliphatiques ou aromatiques (6 min 200 C)s'est avérée la plus adaptée. Les rendements obtenus sont de bons à excellents (74 à 100 %) et les masses molaires sont assez élevées (environ 50. 000 g/mol). Dans le cas de la diamine de type benzylamine, seule la méthode de polycondensation interfaciale, dans un mélange CHCl3/H20, a été opérationnelle. Les rendements obtenus sont très bons (70 à 100 %) et les masses molaires sont plus élevées dans ce cas (jusqu'à 100000 g/mol). Les quelques essais menés à partir du dichlorure d'acide issu de l'isosorbide ont permis, par polycondensation en solution avec des diamines aromatiques d'avoir accès également à de nouveaux polyamides possédant des muses molaires élevées jusqu'à (118000 g/mol) Des techniques d'analyse complémentaires, à savoir : RMN1H, RMN13C, DSC, ATG, Viscosité, ont été utilisées pour caractériser ces polymères.With the objective to develop the isosorbide and to have access to new polyamides from the biomass, two diamines (of aniline type and of benzylamine type) were synthesized with good yields (70 % into two stages) by simple reactions under phase-transition catalysis (PTC). From monomers obtained in the first time new optically active polyamides were synthesized using polycondensation of an optically active isosorbidederived with different aromatic diamines or diacyl chlorides by different method of polymerisation. The polymers we obtained with inherent viscosities in the range 0.11 1.05 dL/g, i. e. with rather high molecular weight up to 118000 g/mol. DSC measurements clearly demonstrate the high thermal stability of these polymers. Several techniques were employed fur polymer analysis and characterization: RMN1H, RMN13C, DSC, TGA, viscosity.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Performance comparison and impact of weather conditions on different photovoltaic modules in two different cities

&lt;span&gt;This work is based on a comparative study of the impact of meteorological conditions as well as the assessment of the production performance of two identical photovoltaic stations installed in two Moroccan cities, the stations are based on three different technologies. The measures of one year of operation from January 2017 to December 2017 were evaluated. The annual average performance ratios were found to be 82.42%, 79.99% and 78.74% in Beni Mellal, and 85.29%, 84.61% and 70.41% in El Jadida for the polycrystalline (pc-Si), monocrystalline (mc-Si), and amorphous (a-Si) respectively. The photovoltaic efficiency was calculated at 12.24%, 11.89%, and 11.71% in Beni Mellal; and 12.59%, 12.49%, and 10.42% in El Jadida by the same order. Statistical analysis was carried out to establish the correlation with photovoltaic (PV) production showed that after irradiation, the temperature is the most influencing meteorological factor for PV production, revealing a degradation in the performance ratio of 2.5%, 2%, and 1% for each increase of 8 °C in temperature for monocrystalline, polycrystalline and amorphous technologies respectively at Beni Mellal. While at El Jadida the reduction in the performance ratio is evaluated by 5.5%, 5.2%, and 3% for each 8 °C increase in temperature for the same order.&lt;/span&gt;</jats:p

Synthesis of New Poly(ether ketone)s Derived from Biobased Diols

International audienceThumbnail image of graphical abstract A new class of poly(ether ketone)s (PEKs) is prepared by polycondensation of various diols produced from biomass and various difluoro aromatics. After optimization of the reaction conditions, polycondensation of isosorbide and 4,4′-difluorodiphenylketone (2a) gives PEK1 with a high yield, moderate viscosity (0.31 dL g−1), and a glass-transition temperature (Tg) of 170 °C. The optimum conditions are applied to the synthesis of a series of PEKs (PEK 2-9) from difluoro agents and sugar diols. The polycondensation of isomannide (1b) with 1,4-di(p-fluorobenzoyl)benzene (2b) gives the best results with an inherent viscosity of 0.52 dL g−1 and the mass spectrum shows an abundance of cyclic structures. Similar conditions are used for the preparation of high-molar-mass copoly(ether ketone)s from a stoechiometric mixture of isosorbide/bisphenol-A