Lipase catalysed synthesis of sebacic and phthalic esters

The enzymatic synthesis and hydrolysis of alkyl sebacates and o-, m-, p-phthalates were studied. Biosyntheses were conducted through alcoholysis of dimethyl phthalates and dimethyl sebacate with 2-ethylhexanol and 3,5,5-trimethylhexanol in a solvent-free medium, using lipases from Candida antarctica (Novozym 435), Rhizomucor miehei (Lipozyme IM) and Porcine pancreas (PPL). It was found that the synthesis and hydrolysis of sebacic acid esters were characterised by a satisfactory rate, however, by low enantioselectivity. The yield of synthesis of di-3,5,5-trimethylhexyl sebacate catalysed by Novozym 435 at 50 °C was 84%, after 20 h of reaction. The degree of conversion, 62.9% after 350 h, was obtained for alcoholysis reaction of dimethyl m-phthalate with 3,5,5-trimethylhexanol. For the enzymes used, no activity was detected at all on both the synthesis and hydrolysis of di-2-ethylhexyl o-phthalate and di-3,5,5-trimethylhexyl o-phthalate.     

High yield lipase-catalyzed synthesis of Engkabang fat esters for the cosmetic industry

Engkabang fat esters were produced via alcoholysis reaction between Engkabang fat and oleyl alcohol, catalyzed by Lipozyme RM IM. The reaction was carried out in a 500 ml Stirred tank reactor using heptane and hexane as solvents. Response surface methodology (RSM) based on a four-factor-five-level Central composite design (CCD) was applied to evaluate the effects of synthesis parameters, namely temperature, substrate molar ratio (oleyl alcohol: Engkabang fat), enzyme amount and impeller speed. The optimum yields of 96.2% and 91.4% were obtained for heptane and hexane at the optimum temperature of 53.9 °C, impeller speeds of 309.5 and 309.0 rpm, enzyme amounts of 4.82 and 5.65 g and substrate molar ratios of 2.94 and 3.39:1, respectively. The actual yields obtained compared well with the predicted values of 100.0% and 91.5%, respectively. Meanwhile, the properties of the esters show that they are suitable to be used as ingredient for cosmetic applications.     

Enzymatic alcoholysis of SO2-uracil analog diacyclonucleosides. Long-distance effect of the substituents on the regioselectivity

Diacetoxy SO₂-uracil analog diacyclonucleosides have been deprotected via lipase-mediated alcoholysis. The reactivity and regioselectivity of the reaction are dependent on the steric hindrance of distant 5-substituents, even if they are as small as a methyl or a 4,5-trimethylene chain, and, in a lesser extent, the electronic or hydrogen bond interactions of 3-carbonyl and hydroxyl-chain groups.     

Zeolites as supports for an enzymatic alcoholysis reaction

A recombinant cutinase from Fusarium solani pisi was immobilized by adsorption on several zeolites and its activity towards the alcoholysis reaction of butyl acetate with hexanol, in organic media (isooctane), was measured as a function of the water content and water activity. The effects of the zeolite framework composition (including cation nature) and acidity were studied. The results were compared with other commonly used supports: polyamide Accurel-PA6, silica and alumina. Both the nature of the cation and the silica:alumina (Si:Al) ratio of the framework revealed to be important parameters. The most promising results were obtained for supports with little acidity and with lower Si:Al ratio. This last observation is in accordance with the results obtained with silica and alumina.     

Kinetic resolution of a diltiazem intermediate by lipase-catalyzed enantioselective alcoholysis

A novel enzymatic resolution of an important alcohol intermediate in the Diltiazem process was developed. The enzymatic reaction involved alcoholysis of the alcohol acetate with butanol, thus obtaining the (R,R)-alcohol and the remaining (S,S)-acetoxy-alcohol in >95% enantiomeric excess. This resolution may serve as the key step in a possible recycling procedure for the waste streams of the Diltiazem process, which will allow a significant increase in the overall process yield.     

Rapeseed oil methyl esters preparation using heterogeneous catalysts

The classical method of fatty acids methyl esters (FAME) production is based on triglyceride transesterification to methyl esters. Sodium hydroxide dissolved in methanol is used as a catalyst. The purpose of this work was to examine a heterogeneous catalyst, in particular calcium compounds, to produce methyl esters of rapeseed oil. This research showed that the transesterification of rapeseed oil by methyl alcohol can be catalysed effectively by basic alkaline-earth metal compounds: calcium oxide, calcium methoxide and barium hydroxide. Calcium catalysts, due to their weak solubility in the reaction medium, are less active than sodium hydroxide. However, calcium catalysts are cheaper and lead to decreases in the number of technological stages and the amount of unwanted waste products. It was found that the transesterification reaction rate can be enhanced by ultrasound as well as by introducing an appropriate reagent into a reactor to promote methanol solubility in the rapeseed oil. Tetrahydrofuran was used as additive to accelerate the transesterification process.     

Biocatalysis: Towards ever greener biodiesel production

The cost of lipases and the relatively slower reaction rate remain as the major obstacles for enzymatic production of biodiesel as opposed to the conventional chemical processes. This paper reviews the starting oils usually employed in biodiesel production, the processes for transforming them to biodiesel placing particular emphasis on enzymatic transesterification. The pros and cons of the lipase-based process, the key operational variables and the technological alternatives for attenuating lipase deactivation are also discussed. Finally, suggestions are made for future studies, paying particular attention to the use of whole cell immobilization in the production process, as this methodology may reduce both the cost of the biocatalyst and dependence on lipase manufacturers.     

Lipase-catalysed preparation of acyl derivatives of the germacranolide cnicin

Several acyl derivatives of cnicin were obtained through lipase-catalysed acylation and alcoholysis reactions. In most reactions lipases showed a regioselective behaviour affording only one product. Longer chain acyl derivatives were prepared at lower temperature than the used in lipase-catalysed reactions, to preclude side products formation. The enzymatic approach let to prepare a family of novel acetyl and fatty acid derivatives of cnicin which are not obtainable following traditional organic synthetic procedures.     

α-Amylase-catalysed synthesis of alkyl glycosides

Alkyl glycosides were synthesised from starch and alcohols using Aspergillus oryzae α-amylase as catalyst. In the degradation of starch by α-amylase, the alcohols competed with water as glycosyl acceptors. In the reaction with methanol, methyl maltoside and methyl maltotrioside were the main alcoholysis products. Conversion of 45 g/l starch in 30% methanol resulted in a product mixture containing 26 mM maltooligosaccharides and 3.6 mM methyl glycosides. With ethanol, propanol and butanol, alkyl maltosides and alkyl maltotetraosides were detected, and with benzyl alcohol, benzyl glycosides having two, three or five glucose units were formed. No alcoholysis reaction occurred with hexanol or octanol. In conclusion, α-amylase is promising for the one-step synthesis of alkyl glycosides having more than one monosaccharide unit, which are difficult to synthesise in other ways.     

Study on response surface methodology (RSM) of lipase-catalyzed synthesis of palm-based wax ester

The synthesis of wax ester using refined, bleached and deodorized (RBD) palm oil and oleyl alcohol catalyzed by lipozyme IM was carried out. Response surface methodology (RSM) based on a five-level, four-variable central composite rotatable design (CCRD) was used to evaluate the interactive effects of synthesis, of reaction time (2.5–10 h), temperature (30–70 °C), amount of enzyme (0.1–0.2 g) and substrate molar ratio (palm oil to oleyl alcohol, 1:1–1:5) on the percentage yield of wax esters. The optimum conditions derived via RSM were: reaction time 7.38 h, temperature 53.9 °C, amount of enzyme 0.149 g, and substrate molar ratio 1:3.41. The actual experimental yield was 84.6% under optimum condition, which compared well to the maximum predicted value of 85.4%.