Thermo-kinetics of lipase catalysed 6-O-glucose decanoatePresentation Transcript
Effects of pure and blended solvents on the thermo-kinetics of lipase-catalyzed synthesis of 6-O-glucosyldecanoate Being a Group-seminar presented To: Fundamental Science in Self Assembly (FS2A) Research group Presented by: Enzymatic Sugar Ester synthesis Project Unit Project Leader: Dr M. Suffian M. Annuar Group members: Assc. Prof. Dr. Thorsten Heidelberge 2. Ahmad Mohammed G. 3. Maryam Farhan Bt. KamaleArifin
Introduction: Surfactants are biphasic having both hydrophilic and hydrophobic groups, and can reduce the surface tension of water when used in specified concentration. The strong attraction between the water molecules and the hydrophilic head group of the surfactants, caused the molecules to assumed self-assembly at the surface, while the hydrophobic end goes away from the water forming a micelles thus their name of “surface active agents”. Surfactants are conventionally produced by chemical catalytic processes, which require high energy consumption, use of environmentally malign chemicals and metallic catalyst. Enzyme-mediated process, is viewed as an alternative environmental friendly process for surfactants production. The primary advantage for incorporation of lipase enzyme in synthetic reactions is the highly improved regio- and stereo- specificities introduced in the reaction process. This enzyme when used in non-aqueous or micro aqueous media, the reaction equilibrium is displaced to favor synthesis rather than hydrolysis.
Methodology Thermometric analysis Residual fatty acid Coloumetric analysis Reactants Pre-equilibration in super saturated KOH solution Airtight 20 ml reaction vials incubated in shaker incubator at controlled temperature and 120 rpm Product extraction , purification and qualitative analyses FT-IR analysis Water content 1H NMR analysis
Results: (a) Effect of temperature on apparent rate constant (k1) and decanoic acid conversion In both pure and blended solvents, it was observed that as the temperature increased, the apparent rate constant also increased (Fig 1), which in turn resulted in an increase in decanoic acid conversion to glucosyldecanoate(Fig 2). Fig 2: max. fatty acid conversion as a function of temperature Fig 1: reaction rate constant as a function of temperature This significant difference in k1 values was attributed to the relative solubility of the reactants in the solvents, which can be predicted from the solvents polarity (Log P). DMSO (C2H6OS, LogP = -1.35) , tertbutanol (C4H10O, LogP = 0.35), and the DMSO:tertbutanol blend exhibits an intermediate polarity value of Log Pmix = -0.62.
(b) Effect of decanoic acid concentration on initial reaction rate In both pure and blended solvents, there is a progressive increase in initial reaction rate with increasing decanoic acid concentration (Figure 3). Fig 3 reaction rate as a function of decanoic acid concentration
(c) Effect of molecular sieves loading on reaction rate and water activity Fig 4 reaction rate as a function of molecular sieves loading Fig 5 water activity as a function of molecular sieves loading
(d) Thermodynamics: Table I Gibbs energy change (ΔG), enthalpy (ΔH) and entropy change (ΔS) as a function of the reaction media Fig 6 Gibbs free energy change as a function of temperature
Conclusion The studies showed the potential use of blend of solvents with opposite polarities in the lipase-catalyzed transesterification process that may improve the feasibility of esters production.