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The extraction of polar molecules from aqueous solution is a challenging task in organic synthesis. 1-Butanol has been used sporadically as an eluent for polar molecules, but it is unclear which molecular features drive its efficiency. Here, we employ free energy simulations to study the partitioning of 15 solutes between water and 1-butanol. The simulations demonstrate that the high affinity of polar molecules to the wet 1-butanol phase is associated with its nanostructure. Small inverse micelles of water are able to accommodate polar solutes and locally mimic an aqueous environment. We verify the simulations based on partition coefficients between water and 1-octanol, and include a blind prediction of the water/1-butanol partition coefficient of cyclohexane-1,2-diol. The calculations are in excellent agreement with experiment, reaching root-mean-square deviations below 0.7 kcal/mol. Actual extractions of cyclohexane-1,2-diol from buffer solutions that mimic cell lysates and suspensions in biocatalytic reactions further exemplify our findings. The yields highlight that extractions with 1-butanol can be significantly more efficient than the conventional protocol based on ethyl acetate.

The commercial application of lipases as biocatalysts for organic synthesis requires simple but efficient methods to immobilize the enzyme, yielding highly stable and active biocatalysts which are easy to recover. In this study, we present a novel method to achieve lipase immobilization by entrapment in chemically inert hydrophobic silica gels which are prepared by hydrolysis of alkyl-substituted silanes in the presence of the enzyme. A typical immobilization procedure uses: an aqueous solution of lipase; sodium fluoride as a catalyst; and additives like polyvinyl alcohol or proteins and alkoxysilane derivatives like RSi-(OMe)3 with R = alkyl, aryl, or alkoxy as gel precursors. The effect of various immobilization parameters like stoichiometric ratio of water, silane, type and amount of additive, type and amount of catalyst, and type of silane has been carefully studied. The new method is applicable for a wide variety of lipases, yielding immobilized lipases with esterification activities enhanced by a factor of up to 88, compared to the commercial enzyme powders under identical conditions. Studies on the stability of sol-gel immobilized lipases under reaction conditions or storage (dry, in aqueous or organic medium) revealed an excellent retention of enzymatic activity. The possible reasons for the increased enzyme activities are discussed. © 1996 John Wiley & Sons, Inc.

New isothiosemicarbazide-based heteronucleating ligands have been synthesised by Ba2+-templated (1:1) macrocyclisation of the polyetherdialdehydes, 3,3′-(3,6-dioxaoctane-1,8-diyldioxy)bis(2-hydroxybenzaldehyde) and 3,3′-(3,6,9-trioxaundecane-1,11-diyldioxy)bis(2-hydroxybenzaldehyde), by using S-methylisothiosemicarbazide as the diamine building block. Thus, the linear polyether dialdehydes (2-hydroxybenzaldehyde-3-yl)-O-(CH2CH2O)n-(3-yl-2-hydroxybenzaldehyde), with n = 3 and 4, react wit S-methylisothiosemicarbazide in the presence of Ba(CF3SO3)2 and Ni(CH3COO)2·4H2O to give two nickel/barium complexes 5 and 6, the crystal structures of which are described. 5: triclinic, P 1 , a=9.886(3), b=12.376(4), c=13.845(6) A , α=73.97(3), β=88.58(3), γ=83.26(3)°, Z=1 ; 6: triclinic, P 1 , a=10.767(2), b=13.221(2), c=15.986(2) A , α=102.57(1), β=101.13(1), γ=109.91(1)°, Z=2 . Treatment of these complexes with an aqueous solution of guanidinium sulfate yields the respective Ba free metallomacrocycles. The crystal structure of one of these (3·H2O) has been determined. 3·H2O: triclinic, P 1 , a=8.106(3), b=11.836(4), c=13.174(4) A , α=88.22(3), β=76.64(3), γ=70.30(3)°, Z = 2 . Its geometry is compared with its parent compound 5. It reveals that coordination of the Ba2+ cation (0.6 A above the mean plane of the O atoms) has little influence on the conformation of the macrocycle. The polyether ring in the two Ba complexes differs in size yet the Ba…Ni distances are remarkably similar (3.664(5) versus 3.723(3) A) suggesting that the two metal atoms although not bonding may be touching.