Retrograde aldol reaction of 3-(1-hydroxy-2,2,2-trichloroethyl)-2,4-pentanedione catalyzed by the bivalent metal complexes of 2,4-pentanedione.

概要

論文の詳細を見る
The bivalent metal complexes of 2,4-pentanedione(M(acac)2) catalyzes the conversion of 3-(1-hydroxy-2,2,2-trichloroethyl)-2,4-pentanedione(A) into chloral and acetylacetone(Hacac) in a chloroform solution. The order of activity of M(acac)2 as the catalyst is: Mg(II), Mn(II)>Co(II)>Ni(II)>Cu(II)<Zn(II). It was found that the catalyzed reaction proceeds through saturation-type kinetics. The Lineweaver-Burk-type plots show linear relationships and are consistent with a mechanism in which a preequilibrium complex formation between M(acac)2 and a substrate is followed by the rate-determining decomposition to give the products. Acetylacetone acts as a competitive inhibitor for the Cu(acac)2-catalyzed reaction. The third stability constant for the Cu–Hacac chelate system can be evaluated from the inhibitor constant as log K3=4.3. The retrograde aldol reactions of 3-(1-hydroxy-2,2,2-trichloroethyl)-5-methyl-2,4-hexanedione and 3-(1-hydroxy-2,2,2-trichloroethyl)-4-phenyl-2,4-butanedione were studied in the same manner as 3-(1-hydroxy-2,2,2-trichloro-ethyl)-2,4-pentanedione. A possible mechanism for the catalysis is proposed.
公益社団法人日本化学会の論文