Kinetic study of 2-butanol O-acylation and sec-butylamine N-acylation catalyzed by Candida antarctica lipase B

Abstract : The aim of this work was to study the differential behavior shown by Candida antarctica lipase B during the O-acylation and N-acylation of monofunctional alcohols and monofunctional amines. To achieve this, 2-butanol and sec-butylamine were used as model molecules. Yields, kinetics and enantioselectivity were studied for both reactions. Although a steady-state ordered ternary complex bi-bi mechanism was obtained for the O-acylation of 2-butanol, a ping-pong bi-bi mechanism was obtained for the N-acylation in case of low sec-butylamine concentrations. The values of apparent kinetic parameters were calculated: the enantiomeric ratios (E) were evaluated and confirmed the preference of C. antarctica lipase B for the (R)-enantiomer, which was consistent with the literature. The enantioselectivity was calculated for the alcohol (E ≈ 3.17) and for the amine (E ≈ 1.34). Concerning the O-acylation, the yields were found to be very similar for both enantiomers R and S. However, both initial rates and yields of the (R)-enantiomer N-acylation were higher than those of the (S)-enantiomer. In the last part of our study, the chemoselectivity of C. antarctica lipase B was evaluated, showing that C. antarctica lipase B was a chemoselective enzyme that preferentially catalyzed the O-acylation to the detriment of the N-acylation (C ≈ 92, for the selective acylation of (R)-enantiomers). These results provide new insights for the synthesis of products issued from the selective acylation of multifunctional substrates such as amino-alcohols.
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Submitted on : Tuesday, January 31, 2017 - 11:19:06 AM
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Florian Le Joubioux, Oussama Achour, Nicolas Bridiau, Marianne Graber, Thierry Maugard. Kinetic study of 2-butanol O-acylation and sec-butylamine N-acylation catalyzed by Candida antarctica lipase B. Journal of Molecular Catalysis B: Enzymatic, Elsevier, 2011, 70, pp.108-113. ⟨10.1016/j.molcatb.2011.02.012⟩. ⟨hal-01450644⟩

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