A Green Process for Synthesis of Geraniol Esters by Immobilized Lipase from Candida Antarctica B Fraction in Non-Aqueous Reaction Media: Optimization and Kinetic Modeling

Abstract

Enzymatic synthesis of molecules such as flavors, perfumes and fragrances has a great commercial advantage of being marketed as “natural” and also it offers exquisite selectivity of enzymes that can be superior over chemical catalysis. The current work focuses on the enzymatic synthesis of geranyl acetate as model compound, including optimization of reaction conditions such as nature of catalyst, reaction media, speed of agitation, mole ratio and temperature. A variety of esters were also synthesized. Geraniol was esterified with various acids, aromatic esters and vinyl esters in 1:4 molar ratio. Among all vinyl ester was the best giving in good yield (77–100 %) as compared to aromatic esters (5–82 %) and acids (7–31 %). Novozym 435 was found to be most active catalyst with ~96 % conversion and 100 % selectivity in 60 min at 55 °C in n-heptane as solvent for geranyl acetate. The maximum reaction rate was estimated (Vmax = 0.2712 mol L−1 min-1) by using the double reciprocal plot. It is a ternary complex (ordered bi-bi) mechanism with inhibition by geraniol.

Novozym 435: the “perfect” lipase immobilized biocatalyst?

“…Esterification of geraniol with some acids was performed using different catalysts, with N435 being the most active one. 144 Geraniol and butanoic acid were esterified by N435 in a solvent-free system with a yield of over 95%, higher than the yield observed using a home-made biocatalyst. 287 N435 was also the best enzyme preparation among the assayed ones in the synthesis of several geraniol esters via an esterification process in a continuous-flow packed-bed reactor (e.g., 87% of geranyl propionate).…”

Synthesis of geranyl acetate by transesterification of geraniol with ethyl acetate over Candida antarctica lipase as catalyst in solvent‐free system

“…Novozyme 435 possesses a flapping lid, which is absent in Lipozyme RM IM and Lipozyme TL IM. The lid overcomes a steric hindrance at active sites of the enzyme, which increases the binding speed of the substrate to the enzyme …”

“…The lid overcomes a steric hindrance at active sites of the enzyme, which increases the binding speed of the substrate to the enzyme. 31,32 S C H E M E 1 Transesterification reaction of geraniol with ethyl acetate to produce geranyl acetate…”

Mathematical modeling of a continuous-flow packed-bed reactor with immobilized lipase for kinetic resolution of (R,S)-2-pentanol

“…To compare the batch and continuous-flow processes of the transesterification of (R,S)-2-pentanol, productivities were calculated from Eqs. (7) and (8), where C P , Q, n, and t represent the product ((R)-2-pentyl butyrate) concentration, volumetric flow rate, mole of the product ((R)-2-pentyl butyrate),and reaction time, respectively. For batch process in which the same immobilized enzyme was used, the values were taken from previous work [3].…”