Enhanced reactivity and enantioselectivity in lipase-catalysed hydrolysis of 12-crown-4 ester via crown ether–metal complexation

1992 ◽  
pp. 1751-1752 ◽  
Author(s):  
Hiroshi Tsukube ◽  
Akio Betchaku ◽  
Yuji Hiyama ◽  
Toshiyuki Itoh
Keyword(s):  
Crown Ether ◽  
Metal Complexation ◽  
Hydrolysis Of

Hydrolysis of substituted crown ether acetals

1989 ◽  
Vol 54 (6) ◽  
pp. 1465-1468 ◽  
Author(s):  
Takumi Oshima ◽  
Toshikazu Nagai
Keyword(s):  
Crown Ether ◽  
Hydrolysis Of

Stabilisierung des reaktiven Methylcarbonat-Ions im Kronenether- Komplex [Cs(18-Krone-6)(CH3CO3)] und dessen Hydrolyseprodukt / Stabilization of the Reactive Methylcarbonate Ion in the Crown Ether Complex [Cs(18-crown-6)(CH3CO3)], and its Hydrolysis Product

2008 ◽  
Vol 63 (9) ◽  
pp. 1101-1106
Author(s):  
Adelė Jonušaite ◽  
Arnold Adam
Keyword(s):  
Crown Ether ◽  
Hydrolysis Product ◽  
Starting Material ◽  
Monoclinic Space Group ◽  
Bidentate Ligands ◽  
Space Group ◽  
Methyl Carbonate ◽  
Hydrolysis Of ◽  
Ether Complex ◽  
Oxygen Atoms

[Cs(18-crown-6)(CH3CO3)] (1) has been obtained by the reaction of CsOCH3 with 18-crown-6 (1,4,7,10,13,16-hexaoxacyclooctadecane) in methanol in a CO2 atmosphere. The compound crystallizes in the monoclinic space group P21/n (no. 14) with a = 12.141(3), b = 8.610(1), c = 17.985(4) Å , β = 91.17(2)° and V = 1879.6(7) Å3. Cs is tenfold coordinated by six oxygen atoms of the crown ether and four oxygen atoms of two methyl carbonate anions which act as bidentate ligands. The slow hydrolysis of the methylcarbonate results in the hydrogencarbonate complex {Cs2(18-crown- 6)2 · [H2(CO3)2] · H2O · CH3OH} (2), the basic structural constitution of the starting material being retained. This new compound crystallizes in the monoclinic space group P21/c with a = 8.657 (7), b = 22.601 (2), c = 19.619 (15) Å, β = 92.09 (6)° and V = 3836.5 (6) Å3.

Hydrolysis of phosphate diester catalysed by transition metal complexes of a salicylaldimine Schiff base bearing dibenzo-18-crown-6

2005 ◽  
Vol 2005 (2) ◽  
pp. 130-134 ◽  
Author(s):  
Jin Zhang ◽  
Jia-qing Xie ◽  
Ying Tang ◽  
Jun Li ◽  
Jian-zhang Li ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Schiff Base ◽  
Crown Ether ◽  
Transition Metal Complexes ◽  
Catalytic Hydrolysis ◽  
Reaction Conditions ◽  
Reaction Systems ◽  
Phosphate Diester ◽  
Nitrophenyl Phosphate ◽  
Hydrolysis Of

A new crowned Schiff base ligand and its cobalt(II) and manganese(III) complexes were synthesised and characterised. These complexes were used to catalyse the hydrolysis of bis(4-nitrophenyl) phosphate (BNPP) in order to mimic the action of hydrolytic metalloenzymes. The kinetics and the mechanism of the titled reactions were investigated. The change of the characteristic ultraviolet spectra of the reaction systems was also analysed. A kinetic mathematical model of BNPP cleavage catalysed by the complexes is proposed. The function of the crown ether ring and the effects of the reaction conditions on the catalytic hydrolysis of BNPP are discussed.

Hydrolysis of crown ether acetals. Effects of ring size and cation binding

1991 ◽  
Vol 56 (2) ◽  
pp. 673-677 ◽  
Author(s):  
Takumi Oshima ◽  
Toshikazu Nagai
Keyword(s):  
Crown Ether ◽  
Cation Binding ◽  
Ring Size ◽  
Hydrolysis Of

An Embodiment on Metal-Complexation of Crown Ether Schiff Bases

2008 ◽  
Vol 28 (2) ◽  
pp. 89-159 ◽  
Author(s):  
Shobhana K. Menon, ◽  
Vrajesh B. Parikh,
Keyword(s):  
Crown Ether ◽  
Schiff Bases ◽  
Metal Complexation
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