Commercial Catalysts and Forthcoming Applications

Catalytic sol-gel lipase immobilizates were rapidly commercialized (by Fluka) after their invention in 1995 because of their remarkably stable activity in esterification reactions (and also in the kinetic resolution of chiral alcohols and amines) along with unique stability (residual activity of 70% even after 20 reaction cycles is common). The original procedure for the encapsulation produced by the fluoride-catalysed hydrolysis of mixtures of RSi(OCH3)3 and Si(OCH3)4 has been improved 

Spotting of so solution with P450 on MTMOS-coated glass slide 

On a laboratory scale, for example, the best performing catalyst for esterification requires double immobilization of lipase within the cages of an ORMOSIL (i-C4H9 TMOS = 5 l) and further coated on the external surface of Celite along with co-entrapment of 18-crown-6 ether 

The high catalyst loading typical of sol gel entrapped catalysts ensures a desirably high substrate/catalyst (S/C) ratio as the major part of the heterogeneous catalyst weight originates from the silicate matrix. For example, in a preparative-scale reaction of the alcohol raol-(2-naphthyl)-ethanol only 250 mg of sol-gel CaLB immobilizate could be used per 10 g of substrate. For comparison, all this makes the process based on sol-gel immobilized lipase very competitive with the commercial BASF process using lipase immobilized on Amberlite to produce the amine at a scale of 1000 tons per year. 

The fundamental sol-gel biocatalytic process has been licensed by IRB to Italian company Indena. The aim is to start production of 

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