The PLE/MPEG catalyzed transesterification of the glycerol ketals rac - 1a and rac - 1d – f with vinyl propionate in toluene proceeded with good selectivities (E=24–34) and gave the enantiomerically enriched S -alcohols 1a and 1d – f , and the S -esters 2a and 2d – f . High selectivities (E=99 and E≥200) were observed in the transesterification of the glycerol ether rac - 3 and its desoxy analog rac - 5 , both having a secondary hydroxy group, with PLE/MPEG. In transesterifications in organic media PLE exhibited a much higher enantioselectivity than in hydrolysis in water.

Application of pig liver esterase catalyzed transesterification in organic media to the kinetic resolution of glycerol derivatives

Synthesis of extracellular lipases by Candida antarctica was induced by adding fat or oil to the culture medium. The highest lipase activity (9.1 U) was obtained after 72 h of cultivation of yeast in medium supplemented with 2% (v/v) 1,2,3-trioleoyl-sn-glycerol. On the basis of SDS-PAGE analysis, Candida antarctica synthesized two forms of lipase having molecular weight of 36 and 52 kDa. Lipase from Candida antarctica showed the highest activity at pH 8.0 and temperature of 35iC and was stable in this range of temperature and pH. Activity of Candida antarctica lipase was higher on substrates having short-chain and medium-chain fatty acids than on these containing long-chain fatty acids. Using Candida antarctica lipase immobilized on Celite 545 for the synthesis of monoacylglycerols, 100% of conversion was obtained after esterification of oleic acid with isopropylidene glycerol. After hydrolysis of protected monoacylglycerols with trifluoroacetic acid, pure monoacylglycerols were obtained.

Synthesis, properties, and application of lipase from candida antarctica for high yield monoacylglycerol biosynthesis

Monoacylglycerols (MAG) are precursors for the synthesis of symmetrical and unsymmetrical triacylglycerols (TAG). In the present study, we improved two methods for synthesizing MAG. One method involved the enzymatic transesterification of vinyl palmitate with glycerol catalyzed by Novozym 435 lipase, and the other method was an enzymatic esterification of 1,2-acetonide glycerol with palmitic acid catalyzed by Novozym 435 lipase and then the cleavage of 1,2-acetonide-3-palmitoyl glycerol in methanol catalyzed by Amberlyst-15 to produce monopalmitin. Pure monopalmitin was obtained after repeated crystallization. The main novelties of this study are twofold: Novozym 435 proved to be very effective in catalyzing the transesterification between vinyl palmitate and glycerol without absorbing glycerol onto silica gel; and the enzyme catalyzed reaction between 1,2-acetonide glycerol and palmitic acid was simpler and safer than the typical method of using 4-dimethyl aminopyridine and N-ethyl-N′-(3-dimethylaminopropyl)-carbodiimide hydrochloride as catalysts. Our methods for the synthesis of monopalmitin are much simpler and environmentally friendlier than the reported methods, and they are economical and scalable to larger quantity production.

Improved Synthesis of Monopalmitin on a Large Scale by Two Enzymatic Methods

The thermodynamics of the lipase-catalyzed transesterification reactions of butyl acetate and 1-phenyl-1-alkanols from C 1 to C 4 have been studied in organic solvents. Equilibrium measurements of the reactions with benzyl alcohol and ( R )-(+)-1-phenyl ethanol were carried out in n -hexane, acetonitrile, 2-butanone, tert -butyl methyl ether, carbon tetrachloride and neat (no solvent added) at 298.15 K. The average value for the equilibrium constant and the standard molar Gibbs energy change Δ r G ° m in these solvents for the reaction with benzyl alcohol (C 1 ) are 0.29 and 3.1 kJ mol −1 , respectively; for the reaction with ( R )-(+)-1-phenyl ethanol (C 2 ) the respective values are 0.11 and 5.4 kJ mol −1 . The difference of 2.3 kJ mol −1 in the values of Δ r G ° m between the C 1 and C 2 alkanols is attributed to increased steric hindrance associated with the additional methyl group in ( R )-(+)-1-phenyl ethanol. In addition, the temperature dependence of the equilibrium constants for the reactions with C 1 and C 2 alkanols were also studied in n -hexane. The standard molar Gibbs energy Δ r G ° m , enthalpy Δ r H ° m , and entropy Δ r S ° m changes at 298.15 K have been calculated from these results. It is seen that the temperature variation of the values of the equilibrium constants is small and that the values of Δ r H ° m are zero within experimental error. The equilibrium constants for the reactions involving ( R )-(+)-1-phenyl-1-propanol (C 3 ) and ( R )-(+)-1-phenyl-1-butanol (C 4 ) were measured in n -hexane only and the values are both 0.11. The fact that the values of the equilibrium constants for the reactions involving C 2 –C 4 are constant is consistent with the view that no additional steric hindrance is caused by adding more than one methylene group to the ( R )-(+)-1-phenyl-1-alkanol reactant.

Thermodynamics of the lipase-catalyzed transesterification of 1-phenyl-1-alkanols and butyl acetate in organic solvents

Els monoacilglicerols (MAGs) enantiomerics son intermedis de gran interes i la seva produccio mitjancant enzims ofereix vies alternatives a les reaccions quimiques tradicionals. Aquesta tesi te com a objectiu la seva sintesi a partir de dos precursors dels MAGs (el rac-palmitat de solketil i el rac-palmitat de glicidil), utilitzant micelis de fongs aillats de residus de la industria de l’oli com a biocatalitzadors.

En un primer intent d’obtenir MAGs, es va avaluar l’activitat epoxid-hidrolasica dels micelis enfront el rac-fenil glicidil eter, el rac-benzil glicidil eter, el rac-1,2-epoxihexa i el rac-1,2-epoxiocta. A continuacio, els micelis escollits es van utilitzar en la hidrolisi del rac-palmitat de glicidil. Nomes es va obtenir MAG amb el miceli de Penicillium sp., pero com a mescla racemica. L’efecte matriu associat a les reaccions amb micelis com ara la recuperacio de l’analit adsorbit en la biomassa o l’extraccio de components dels biocatalitzadors es van compensar realitzant l’extraccio despres de fortificar les mostres i patrons.

En un segon intent, el palmitat de glicidil enantioenriquit i sintetitzat pel miceli de Mucor fragilis, es va hidrolitzar amb el miceli de Penicillium sp. La hidrolisi enzimatica del MAG enantiomeric va dificultar la seva obtencio.

Ús de micelis fúngics com a biocatalitzadors en reaccions d’hidròlisi

Application of Vinyl Esters for the Lipase‐catalyzed High‐Yield Synthesis of Monoacylglycerols

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Application of Vinyl Esters for the Lipase‐catalyzed High‐Yield Synthesis of Monoacylglycerols