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The performance of Candida antarctica lipase B (CALB) has been evaluated in 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4)/water mixtures in a wide range of molar fractions (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m1"><mml:mrow><mml:msub><mml:mi mathvariant="normal">χ</mml:mi><mml:mrow><mml:mi>B</mml:mi><mml:mi>M</mml:mi><mml:mi>I</mml:mi><mml:mi>M</mml:mi><mml:mi>B</mml:mi><mml:mi>F</mml:mi><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>) with and without 1-dodecyl-3-methylimidazolium tetrafluoroborate (C12-MIMBF4), a surfactant derived from BMIMBF4. The main aim of this work is to evaluate the influence of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m2"><mml:mrow><mml:msub><mml:mi mathvariant="normal">χ</mml:mi><mml:mrow><mml:mi>B</mml:mi><mml:mi>M</mml:mi><mml:mi>I</mml:mi><mml:mi>M</mml:mi><mml:mi>B</mml:mi><mml:mi>F</mml:mi><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math> over micellar aggregates to assess the activity of enzymatic reactions. The investigated reaction corresponds to the hydrolysis of the substrate p-nitrophenyl laureate in each <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m3"><mml:mrow><mml:msub><mml:mi mathvariant="normal">χ</mml:mi><mml:mrow><mml:mi>B</mml:mi><mml:mi>M</mml:mi><mml:mi>I</mml:mi><mml:mi>M</mml:mi><mml:mi>B</mml:mi><mml:mi>F</mml:mi><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>. The kinetic study for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m4"><mml:mrow><mml:msub><mml:mi mathvariant="normal">χ</mml:mi><mml:mrow><mml:mi>B</mml:mi><mml:mi>M</mml:mi><mml:mi>I</mml:mi><mml:mi>M</mml:mi><mml:mi>B</mml:mi><mml:mi>F</mml:mi><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math> at around 0.2 proved to be a border point in enzymatic activity. At <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m5"><mml:mrow><mml:msub><mml:mi mathvariant="normal">χ</mml:mi><mml:mrow><mml:mi>B</mml:mi><mml:mi>M</mml:mi><mml:mi>I</mml:mi><mml:mi>M</mml:mi><mml:mi>B</mml:mi><mml:mi>F</mml:mi><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math> = 0.1, the lipase activity increases in the presence of C12-MIMBF4. However, at higher concentrations, BMIMBF4 has a negligible effect over the lipase activity. These results suggest specific interactions between water and BMIMBF4 molecules in relation to CALB. This research highlights the superactivity phenomenon driven by the reaction media and the micelle interface. In this interfacial interaction, BMIMBF4 acts directly on the changes induced on the enzyme upon its interaction with the micellar interface. This study opens a green perspective toward the biocatalysis field.

The reactions between 2-chloro-5-nitro pyrimidine with a serie of α-nucleophile derivatives were kinetically evaluated. The kinetic study was carried out in aqueous media and the data shown an unusual split on the Brønsted type-plot, opening a controversial discussion based on reactivities and possible reaction pathways. These split Brønsted type-plots are discussed over the hypothetical transition state (TS) structures associated to concerted or stepwise mechanisms with emphasis on hydrogen bond interactions between electrophile/nucleophile pair able to determine the reactivities and the plausible reaction routes.

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