不斉加水分解反応場の熱力学的評価

ミセルおよび二分子膜系における疎水性相互作用

抄録

Stereoselective hydrolysis of p-nitrophenyl N-acyl-D (L) -phenylalaninates by the bilayer and micellar catalytic systems of L-histidine derivatives and surfactants were performed. The noteworthy aspects are as follows : (a) According to the isokinetic temperature (β), the hydrolysis of enantiomer substrates in the bilayer systems might be entropy-driven (β<T (average value of experimental temperatures)), whereas that in the micellar systems might be enthalpy-driven (β>T). The stronger hydrophobic microenvironment of the bilayer systems would probably be connected with the entropy-driven nature ; (b) the enantioselectivity was markedly elevated at temperatures somewhat higher than the phase transitions in the bilayer systems; (c) the enantioselectivity was fairly enhanced by addition of cholesterol and micelles in the bilayer systems, and it would be attributed to the change of hydrophobic microenvironments on the basis of the β value in connection with T.