Luciane F. de Oliveira

Ionic Liquid Supported Acid/Base-Catalyzed Production of Biodiesel

The transesterification (alcoholysis) reaction was successfully applied to synthesize biodiesel from vegetable oils using imidazolium-based ionic liquids under multiphase acidic and basic conditions. Under basic conditions, the combination of the ionic liquid 1-n-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMINTf2), alcohols, and K2CO3 (40 mol %) results in the production of biodiesel from soybean oil in high yields (>98%) and purity. H2SO4 immobilized in BMINTf2 efficiently promotes the transesterification reaction of soybean oil and various primary and secondary alcohols. In this multiphase process the acid is almost completely retained in the ionic liquid phase, while the biodiesel forms a separate phase. The recovered ionic liquid containing the acid could be reused at least six times without any significant loss in the biodiesel yield or selectivity. In both catalytic processes (acid and base), the reactions proceed as typical multiphasic systems in which the formed biodiesel accumulates as the upper phase and the glycerol by-product is selectively captured by the alcohol-ionic liquid-acid/base phase. Classical ionic liquids such as 1-n-butyl-3-methylimidazolium tetrafluoroborate and hexafluorophosphate are not stable under these acidic or basic conditions and decompose.

Third-order nonlinear optical responses of colloidal Ag nanoparticles dispersed in BMI.BF 4 ionic liquid

The third-order nonlinear optical responses of tetrafluoroborate 1-n-butyl-methylimidazolium (BMI.BF4) and colloidal Ag nanoparticles dispersed in this medium were investigated. Hybrid organic-metallic colloids consisting of silver nanoparticles dispersed in BMI.BF4 were synthesized. Using the thermally managed Z-scan technique, the electronic contribution to the nonlinear refractive indexes of the BMI.BF4 and colloids with two different nanoparticles filling factors were measured, as well as the medias nonlinear absorption. The performance of these systems for all-optical switching was also evaluated. The obtained results indicate that these are promising candidates for the development of nonlinear optical applications.

Nonlinear Optical Properties Of Au And Ag Nanoparticles Dispersed In Ionic Liquids

Hybrid organic-metallic colloids consisting of Au and Ag nanoparticles dispersed in two different ionic liquids were synthesized. Our results indicate that these systems are promising candidates to the development of nonlinear optical applications.

New Efficient Route to the Synthesis of Enantiopure (+) and (−) Bicyclo[2.2.1]heptan‐syn‐2,7‐diol using Lipase‐Catalyzed Transesterifications

Abstract Starting from racemic 7,7‐dimethoxy‐1,4,5,6‐tetrachlorobicyclo[2.2.1]hept‐5‐en‐2‐endo‐ol (±)‐7, using lipase‐catalyzed transesterification and a series of standard procedures, we prepared the enantiomers (+)‐(2R, 7S) and (−)‐(2S, 7R) bicyclo[2.2.1] heptan‐2,7‐syn‐diol 3 through a new alternative route with excellent yields and enantiomeric excess (up to 99%). These chiral bidentate compounds possess very rigid molecular structures and a favorable stereochemistry for metal coordination, thus becoming promising chiral ligands for asymmetric synthesis.