Browsing by Subject "Catalysis"
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- PublicationOpen AccessA Thiourea-based Rotaxane Catalyst: Nucleophilic Fluorination Phase-Transfer Process Unlocked by the Mechanical Bond(American Chemical Society, 2025-03-18) Martínez Cuezva, Alberto; Berná Cánovas, José; Puigcerver Alarcón, Julio; Juan S. Santiago Dato; Alajarín Cerón, Mateo; Química OrgánicaWe report a five-component clipping approach using activated isophthaloyl-derived esters to synthesize an amide-based thiourea rotaxane. This method overcomes acyl chloride limitations with nucleophilic thiourea threads. The steric hindrance of the mechanical bond enables, for the first time, an interlocked thiourea as a hydrogen-bonding phase-transfer organocatalyst in nu-cleophilic fluorinations. This highlights how mechanical bonds expand thiourea catalysis to processes previously incompatible with conventional catalysts.
- PublicationOpen AccessHighly selective biocatalytic synthesis of monoacylglycerides in sponge-like ionic liquids(RSC, 2017) Gómez, Celia; Sánchez-Gómez, Gregorio; García-Verdugo, Eduardo; Luis, Santiago V.; Lozano Rodríguez, Pedro; Nieto Cerón, Susana; Bioquímica y Biología Molecular B e InmunologíaThe biocatalytic synthesis of monoacylglycerides (MAGs) was carried out by the direct esterification of fatty acids (i.e. oleic, palmitic, myristic and lauric acids, respectively) with glycerol in different ionic liquids (ILs) based on cations with long alkyl side-chains (i.e. 1-hexadecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C16mim][NTf2], 1-dodecyl-3-methylimidazolium tetrafluoroborate [C12mim][BF4]). Although all ILs have been shown as suitable reaction media for Novozym 435-catalyzed esterification of glycerol with free fatty acid, a highly selective selectivity of MAGs was only observed for the [C12mim][BF4] case (i.e up to 99% selectivity and yield for the monolaurin case). Furthermore, as these ILs are temperature switchable ionic liquid/solid phases that behave as sponge-like system, a straightforward protocol for IL-free MSGs recovery, based on iterative centrifugations at controlled temperature, has been developed.
- PublicationOpen AccessOptimizing an Organocatalyzed Process in an Undergraduate Laboratory: A Solvent Screening(American Chemical Society, 0019-11-19) Puigcerver Alarcón, Julio; Martínez Cuezva, Alberto; Química OrgánicaIn this undergraduate organic laboratory study, an extensive solvent screening has been 10 meticulously designed for the optimization of the L-proline-organocatalyzed intermolecular aldol reaction involving acetone and p-nitrobenzaldehyde. The experimental procedure entailed selecting specific solvents, analyzing the reaction crude through NMR spectroscopy, and subsequently, purifying the aldol adducts to measure their enantiomeric ratios via HPLC provided with chiral column. Remarkably, this comprehensive investigation was efficiently conducted within two concise 2-hour 15 laboratory sessions, together with 1-hour seminar session, rendering it highly suitable for both Bachelor's and Master's degree programs. Conducted at room temperature, the experiments unveiled significant variations in both yields and enantiomeric excess of the aldol products, and the byproducts proportions, depending on the solvent of choice. This experiential learning opportunity empowers students to gain practical insights into organocatalyzed transformations, purification techniques, and 20 chromatographic analysis, enhancing their proficiency as organic chemists.
- PublicationOpen AccessPd(II)-catalyzed deprotection of acetals and ketals containing acid sensitive functional groups(Elsevier, 2014-02-05) Juliá Hernández, Francisco; Arcas, Aurelia; Vicente, José; Química InorgánicaThe pincer complex [Pd(C1,O1,N1-L)(NCMe)]ClO4 (L = monoanionic ligand resulting from deprotonation of the acetyl group of the dimethyl monoketal of 2,6-diacetylpyridine) is used for the high-yield and selective catalytic hydrolysis of aliphatic, aromatic, cyclic and acyclic dimethyl-acetals, - ketals and dioxolanes, even in the presence of large substituents. Other protecting groups, as THP or TBDMS, or very acid-sensitive alcohols were not affected. The catalyst is easily prepared in high yield from Pd(AcO)2 and 2,6-diacetylpyridinium perchlorate stable to air and moisture, easily and fully recoverable and reusable.
- PublicationOpen AccessUrea-based [2]Rotaxanes as Effective Phase-Transfer Organocatalysts: Hydrogen-Bonding Cooperative Activation Enabled by the Mechanical Bond(ACS Publicatins, 2024-07-08) Puigcerver, Julio; Zamora Gallego, José María; Marín Luna, Marta; Martínez Cuezva, Alberto; Berná Cánovas, José; Química Orgánica