Enzymatic synthesis ionic liquids

In the first publication describing the preparative use of an enzymatic reaction in ionic liquids, Erbeldinger et al. reported the use of the protease thermolysin for the synthesis of the dipeptide Z-aspartame (Entry 6) [34]. The reaction rates were comparable to those found in conventional organic solvents such as ethyl acetate. Additionally, the enzyme stability was increased in the ionic liquid. The ionic liquid was recycled several times after the removal of non-converted substrates by extraction with water and product precipitation. Recycling of the enzyme has not been reported. It should be noted, however, that according to the log P concept described in the previous section, ethyl acetate - with a value of 0.68 - may interfere with the pro-... 

Irimescu and Kato have recently described an interesting example of enzymatic KR in ionic liquids instead of organic solvents (Scheme 7.4) [12]. The resolution with CALB is based on the fact that the reaction equilibrium was shifted toward the amide synthesis by the removal of water under reduced pressure. Nonsolvent systems have been also employed in this enantioselective amidation processes, reacting racemic amines with aliphatic acids. The best reaction conditions for the conversion of acids to amides was observed using CALB at 90 °C under vacuum. Meanwhile, no... 

In the synthesis of A-acetyllactosamin from lactose and A-acetylglucosamine with (3-galactosidase (289,290), the addition of 25 vol% of the water-miscible ionic liquid [MMIM][MeS04] to an aqueous system was found to effectively suppress the side reaction of secondary hydrolysis of the desired product. As a result, the product yield was increased from 30 to 60%. Product separation was improved, and the reuse of the enzymatic catalyst became possible. A kinetics investigation showed that the enzyme activity was not influenced by the presence of the ionic liquids. The enzyme was stable under the conditions employed, allowing its repeated use after filtration with a commercially available ultrafiltration membrane. 

Reetz, M.T., W. Wiesenhofer, G. Francio and W. Leitner, Continuous Flow Enzymatic Kinetic Resolution and Enantiomer Separation Using Ionic Liquid/Supercritical Carbon Dioxide Media, Advanced Synthesis Catalysis, 345, 1221-1228 (2003). 

In addition to free fatly acids and their esters as previously described, compounds with antioxidant potency were also used as acyl donors. In order to investigate the synthesis of hybrid antioxidants, the enzymatic acylation of escuhn catalyzed by immobilized CALB in the ionic liquids [bmtm]BF4 and [bmim]PF6 was investigated using several phenolic acids as well as their corresponding vinyl esters. 

As can be seen in Figure 9.4, the enzymatic synthesis of hybrid antioxidants of esculin is feasible in ionic Hquids, resulting in good conversion yields. The conversion yields obtained were higher in ionic liquid [bmim]PF6 as compared to [bmim]BF4 for all phenohc acids tested, while the use of phenohc acid esters in transesterification reactions led to higher conversion yields in both ionic hquid media used. 

Hernandez FJ, de los Rios AP, Gomez D, Rubio M, ViUora G. A new recirculating enzymatic membrane reactor for ester synthesis in ionic liquid/supercritical carbon dioxide biphasic systems. Appl Catal B 2006 67 121-126. 

The work from Sheldon s group [10] was the first to present the use of ionic liquids in the enzymatic synthesis of esters. Since then, there have been many reports on biosynthesis of esters in ionic liquids. De los Rios et al. [64,65] synthesised a wide range of aliphatic organic esters, commonly used in the perfumery, flavour and pharmaceutical industries, by transesteriflcation from vinyl esters and alcohols catalysed by free CaLB in different 1,3-dialkylimidazolium-based ILs (Fig. 7.2). They analysed the effects of the alkyl chain lengths of the acyl donor and the alcohol. The optimum (C6 for acyl donor and C4 for alcohol) chain lengths were found because the activity decreased with further increase in alkyl chain length. The authors attributed the enzyme behaviour to a substrate modulation mainly due to the different affinity of the lipase towards the different substrates and steric hindrance and denaturalisation by small alcohol molecules. 

Lozano P, De Diego T, Carrie D, Vaultier M, Iborra JL (2003) Enzymatic ester synthesis in ionic liquids. J Mol Catal B Enzym 21 9-13... 

Gorke JT, Okrasa K, Louwagie A, Kazlauskas RJ, Srienc F (2007) Enzymatic synthesis of poly(hydroxyalkanoates) in ionic liquids. J Biotechnol 132 306-313... 

Ionic Liquids/Supercritical Carbon Dioxide as Advantageous Biphasic Systems in Enzymatic Synthesis... 

Fig. 8.1 Experimental set-up of the recirculating enzymatic membrane reactor used for the synthesis of butyl propionate from vinyl propionate and 1-butanol catalysed by Candida antarctica lipase B in supercritical carbon dioxide and supercritical carbon dioxide/ionic liquid biphasic system [17]...

Mori M, Gomez Garcia R, Belleville MP et al (2005) A new way to conduct enzymatic synthesis in an active membrane using ionic liquids as catalyst support. Catal Today 104 313-317... 

Kaftzik N, Wasserscheid P, Kragl U (2002) Use of ionic liquids to increase the yield and enzymatic stability in the 3-galactosidase catalyzed synthesis of N-acetyllactosamine. Org Process Res Dev 6 553-557... 

Marcilla R, De Geus M, Mecerreyes D et al (2006) Enzymatic polyester synthesis in ionic liquids. Eur Polym J 42 1215-1221... 

Uyama H, Takamoto T, Kobayashi S (2002) Enzymatic synthesis of polyesters in ionic liquids. Polym J 34 94-95... 

Gorke, J. Kazlauskas, R. J. Srienc, F. Enzymatic synthesis of PHAs using ionic liquids as solvents ACS Polymer Preprints, 2006,47(2), 233. 

Mori T, Kobayashi A, Okahata Y (1998) Biocatalytic esterification in supercritical carbon dioxide using a Upid-coated lipase. Chem Lett 9 921-922 Mori M, Gomez Garcia R, BeUeviUe MP (2005) A new way to conduct enzymatic synthesis in an active membrane using ionic liquids as catalyst support. Catal Today 104 313-317 Morley KL, Kazlauskas RJ (2005) Improving enzyme properties when are closer mutations better TIBTECH 23(5) 231-237... 

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