Novel biocatalytic esterification reactions on fatty acids: synthesis of sorbitol 1(6) - monostearate

Abstract

Dedicated to Professor Sukh Dev on his 80th birthday (received 16 Jan 03; accepted 06 May 03; published on the web 08 May 03) AbstractAspergillus terreus lipase has exhibited novel capability of catalyzing esterification reaction between fatty acids (C 4 -C 18 ) and primary, secondary and tertiary monohydric alcohols. Although, the lipase efficiently catalyzed the esterification of saturated stearic acid (C 18:0 ), it failed to accept the monounsaturated oleic acid (C 18:1 ) as the substrate which is also a C 18 acid, but has a double bond. Thus, this enzyme has a great potential to be used as a selective catalyst for the separation of almost identical saturated and unsaturated fatty acids in their mixtures. Extending this work, highly efficient and regioselective conversion of sorbitol to its 1(6) -monostearate has been achieved by Aspergillus terreus lipase -mediated esterification in n-hexane. Ninety four per cent conversion to the ester was achieved in 12 h on optimizing four physico-chemical factors, i.e. molar ratios of substrates, temperature, solvent and water activity. Aspergillus terreus lipase immobilized on Accurel was efficient in the synthesis of sorbitol stearate and was reused three times without any significant decline in its activity, yields were further enhanced to 96 % on using the immobilized enzyme.

Green Formulation Strategy for Preparing Oil-in-Water Emulsions via Lipase-Catalyzed Transesterification

“…In this study, lipase AY showed the selectivity toward the primary hydroxyl groups of the sorbitol moiety similar to that reported previously. , Thus, these results demonstrated that the position of alkyl substitution was not affected by the use of an aqueous biphasic reaction medium as compared to the organic solvent. Moreover, the acylation at the secondary hydroxyl group of the sorbitol moiety was shown to occur.…”

“…According to previous studies, the acylation of hydroxyl groups of sugar/sugar alcohol moiety resulted in a downfield shift of the peak corresponding to the O-acylated carbon and an upfield shift of the peak corresponding to the neighboring carbons 5,45,46 . Based on this knowledge and a bi- In this study, lipase AY showed the selectivity toward the primary hydroxyl groups of sorbitol moiety similar to that reported previously 5,27 . Thus, these results demonstrated that the position of alkyl substitution was not affected by the use of an aqueous biphasic reaction medium as compared to organic solvent.…”

“…In order to prepare oil-in-water emulsions, the common procedure would be to put the oil in contact with an aqueous phase containing a water-soluble surfactant, for instance, a sorbitol ester prepared by an enzyme-catalyzed reaction (Figure ). − We designed an alternative procedure where the required amount of surfactant would be synthesized from the oil before the emulsification step. Thus, instead of considering the enzyme-catalyzed synthesis of surfactant as an industrial operation providing one ingredient for the formulation process, we proposed to include the enzyme-catalyzed synthesis as a unit operation of the formulation process itself (Figure ).…”

“…The commercial oil sample was characterized as a 50/50 mixture of two caprylic/capric diglycerides isomers (see Experimental). In order to prepare oil-in-water emulsions, the common procedure would be to put the oil in contact with an aqueous phase containing a water-soluble surfactant, for instance a sorbitol ester prepared by an enzyme-catalyzed reaction (Figure 1) [26][27][28] . We designed an alternative procedure where the required amount of surfactant would be synthesized from the oil before the emulsification step.…”

Synthesis of Biobased Polyester Polyol through Esterification of Sorbitol with Azelaic Acid Catalyzed by Tin(II) Oxide: A Kinetic Modeling Study

“…Further increasing the molar ratio, the negative effect toward the conversion because the excess SL has blocked the active sites on the catalyst surface and subsequently prevent it from nucleophilic attack. 16 Despite the identical conversion at sixth hour, the M SL:AA of 4:1 was chosen and used for subsequent studies due to its superior initial rate of reaction. 3.1.3.…”