Browsing by Subject "Solvent free"

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    Branched saturated esters and diesters : sustainable synthesis of excellent biolubricants
    (Elsevier, 2024-01-08) Máximo, M.; Bastida, J.; Montiel, C.; Gómez, M.; Murcia, M.D.; Barqueros, C.; Ortega Requena, Salvadora; Ingeniería Química
    The enzymatic production of biolubricants with desirable properties such as high viscosity index and resistance to oxidation is investigated. These characteristics are ascribed to their branched structure and high molecular weight, as well as, to the absence of unsaturated bonds in the molecule. Solvent-free processes with moderate enzyme concentrations (up to 5% wt.) and reaching conversions of 95% or more, have been conducted. Firstly, up to fifteen branched esters and diesters, all of them saturated, are obtained from a branched acid, 2-methylhexanoic acid, and a variety of linear and branched alcohols and linear diols. Among them, three esters have viscosity indexes close to 200 or higher (1,10-decanediolyl 2-methylhexanoate, 1,12-dodecanediolyl 2-methylhexanoate and 2-octyl-1-dodecanoyl 2-methylhexanoate). For the synthesis of these compounds, optimization of biocatalyst concentration and temperature has been carried out, reaching conversions above 95% within operation times between 2 and 3.5 h.
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    Open Access
    Sustainable set-ups for the biocatalytic production and scale-up of panthenyl monoacyl esters under solvent-free conditions
    (American Chemical Society, 2023-03-22) Nieto Cerón, Susana; Bernal Palazón, Juana María; García Verdugo, Eduardo; Donaire González, Antonio; Lozano Rodríguez, Pedro; Villa Aroca, Rocío; Química Inorgánica; Facultades de la UMU::Facultad de Química
    A sustainable scaling-up process for the biocatalytic production of new bioactive provitamin-B5 monoacyl esters has been demonstrated. A solvent-free reaction protocol based on the formation of eutectic mixtures between neat substrates render to highly efficient direct esterification of free fatty acids (i.e. from C6 to C18 alkyl chain length) with panthenol catalyzed by lipase. The scale-up from 0.5 to 500 g was evaluated by means of several reaction systems (i.e. ultrasound-assistance, orbital shaking, rotary evaporator, and mechanical stirring coupled to vacuum). For all reactor systems, the yield in panthenyl monoacyl esters was improved by increasing the length of the alkyl chain of the fatty acid (i.e. from 63 % yield for panthenyl butyrate to 83 % yield for panthenyl myristate). The best results (87 % - 95 % product yield, for all cases) were obtained upon a scale-up (50-500 g size) and when a vacuum system was coupled to the biocatalytic reaction unit. Under the optimized conditions a five-fold reduction of the amount of biocatalyst with respect reactors without vacuum was achieved. The recovery and reuse of the immobilized enzyme for 5 operation cycles was also demonstrated. Finally, different metrics have been applied to assess the greenness of the solvent-free biocatalytic synthesis of panthenyl monoesters here reported.