Kinetic Studies on Lipase-Catalyzed Acetylation of 2-Alkanol with Vinyl Acetate in Organic Solvent

Abstract

OH], and different organic solvents ( ) in order to clarify the second order rate constants for (R)-(1) and (S)-(1), and the enantioselectivity which are affected by solvent 309Correspondence to: Hirofumi Hirata, Department of Bioscience and Technology, School of Engineering, Hokkaido Tokai University, 5-1 Minamisawa, Minami-ku, Sapporo 005-8601, JAPAN E-mail: hirata@db.htokai.ac.jp Accepted February 26, 2007 (received for review December 7, 2006 Journal of Oleo Science Copyright ©2007 by Japan Oil Chemists ' Society J. Oleo Sci. 56,(6) 309-317 (2007) Abstract: Lipase-catalyzed acetylation of 2-alkanol with vinyl acetate has been studied kinetically using Burkholderia cepacia lipase (BCL), enantiomerically pure (R)-and (S)-2-alkanols and different organic solvents. The rate equation was derived by the steady state method for the simplified mechanism. The second order rate constants (k R and k S ) for (R)-and (S)-2-alkanols were evaluated from the slopes of the double reciprocal plots, v -1 vs. [2-alkanol] -1 , where v is the initial rate of the reaction. The log k R value increased with the solvent hydrophobicity log P, where P is a partition coefficient of a given solvent between octanol and water. The log k S value also increased with log P except the bulky solvents such as 1,4-dioxane and cyclohexane, in which the rates were faster than those expected from the log k S vs. log P plot. The slope of log k S vs. log P plot was larger than that for (R)-2-alkanol. Thus, log E (E=k R /k S : enantioselectivity) decreased with log P except the bulky solvents. The rate constants and the enantioselectivity were different depending on the structure (carbon number CN) of 2-alkanol. The log E vs. CN plot was minimized at CN=8 and 10 and the log k S vs. CN plot maximized at CN=8 and 10. In contrast the log k R vs. CN plot showed a different feature from the log E vs. CN plot. These facts suggest that dependence of E on CN is more strongly affected by the reactivity of (S)-2-alkanol than that of (R) isomer in this acetylation. Kinetic Studies on Lipase-Catalyzed Acetylation of 2-Alkanol with Vinyl Acetate in Organic Solvent

Kinetics and modeling of (R,S)‐1‐phenylethanol acylation over lipase

“…Typically, activated esters, such as vinyl acetate or 4-chlorophenyl acetate, have been used as acyl donors in kinetic resolution of secondary alcohols [2,3]. This is because the reaction rate is higher when the acylation is irreversible.…”

Kinetic modeling of lipase‐mediated one‐pot chemo‐bio cascade synthesis of R‐1‐phenyl ethyl acetate starting from acetophenone

“…Correlations of 1.000 indicate perfect positive correlation; 0.000 means that there is no correlation at all, and −1.000 represents perfect negative correlation. The correlation matrix shows that the parameters k 6 and K B , k +d and k 1 and k 7 and K A are highly correlated with each other, meaning that increasing one parameter will increase the other one.…”

“…15 Most of the kinetic modeling studies are based on initial reaction rates. 6 There is a dearth of literature on kinetics and modeling of lipase-mediated chemo-bio cascades reactions. For these reasons, the purpose of this work was to propose a reaction mechanism which could describe kinetics of chemo-bio synthesis of R-1-phenyl ethyl acetate over Pd/Al 2 O 3 and immobilized lipase in ethyl acetate.…”

Enzimas em biocatálise (esterificação de aminas, adição de Michael, clonagem e expressão de álcool desidrogenase)

“…Por fim, a amina 3 apresentou o melhor ee (11%) e conversão de 2% quando a enzima foi a HPL. Ésteres ativados, tais como o acetato de vinila ou acetato de 4-clorofenila, têm sido utilizados como dadores de acila em resolução cinética de álcoois (Kirilin et al, 2010;Hirata et al, 2007;Jung et al, 2000). Os ésteres ativados, ou seja, aqueles que contêm grupos insaturados ou grupos funcionais eletronegativos, são conhecidos por reagir mais rapidamente do que o acetato de etila como um doador de acila (Jung et al, 2000).…”

“…Isto ocorre porque a velocidade da reação torna-se mais elevada quando a acilação é irreversível. Por exemplo, a resolução cinética com acetato de vinila é irreversível, pois um produto instável, o álcool vinílico, é formado em quantidades estequiométricas e rapidamente reage para formar acetaldeído via tautomerização ceto-enólica (Hirata et al, 2007). Quando um grupo acil doador saturado, tal como ace-2.2 Resultados e Discussão 43 tato de etila, é utilizado, o etanol é formado como um subproduto e a reação é reversível.…”