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Schiff base ligands hydrolysis

In 1962, it was reported that when silver nitrate was added to a warm aqueous solution of acacenH2, a finely divided colourless compound immediately precipitated. If instead the solution was heated on a water bath, then an uncharacterized dark brown substance formed. Analytical data and conductivity measurements suggested that the former complex was Ag2(acacenH2)(N03)2.391 The decomposition observed was most likely caused by hydrolysis, since many Schiff base ligands hydrolyze rapidly in water. [Pg.825]

Simple esters cannot be allylated with allyl acetates, but the Schiff base 109 derived from o -amino acid esters such as glycine or alanine is allylated with allyl acetate. In this way. the o-allyl-a-amino acid 110 can be prepared after hydrolysis[34]. The Q-allyl-o-aminophosphonate 112 is prepared by allylation of the Schiff base 111 of diethyl aminomethylphosphonates. [35,36]. Asymmetric synthesis in this reaction using the (+ )-A, jV-dicyclohex-ylsulfamoylisobornyl alcohol ester of glycine and DIOP as a chiral ligand achieved 99% ec[72]. [Pg.306]

Partial hydrolysis of a potentially heptadentate Schiff-base tripodal ligand derived from tris-(2-aminoethyl)amine and 2-hydroxyacetophenone, induced by copper(II) salts, was reported and the final copper(II) complex (377) was characterized.333 Using salicylaldehyde as a co-ligand, with a copper(II) complex (378), catalytic epoxidation was demonstrated 334... [Pg.817]

The kinetic parameters above are very similar to those for the hydrolysis of a simple Schiff base, benzalaniline, having an activation energy of 13.2 kcal. and an entropy of activation of about —37 e.u. (40). It appears that the rate determining step for hydrolyses of the complexes is the second step, the splitting off of the aldehyde. Under suitable conditions, the intermediates in such hydrolyses for bis complexes (of Schiff bases derived from ethylenediamine) have been isolated. Only one of the ligands is hydrolyzed, and the nitrogen which had been present in the Schiff base is still coordinated to the central metal (17). [Pg.163]

Reactions of Schiff bases coordinated with metal ions have been examined from the standpoint of stability and reactivity. Eichhorn (23, 25) examined the complex formed between bis-(thiaphenal)ethylene-diimine and copper(II). It was found that, when complexed to copper(II), the ligand becomes unstable and hydrolysis occurs this leads to the aldehyde and the copper-ethylenediamine complex. [Pg.264]

A kinetic study of the hydrolysis of JV-salicylideneaniline (113) in the presence and absence of cobalt(II), nickel(II), copper(II) and zinc(II), using 10% ethanol-water as solvent, has been carried out by Dash and Nanda. The (1 1) Schiff base-metal complexes (ML ) were found to undergo acid-catalyzed hydrolysis at rates decreasing with the thermodynamic stabilities of the complexes, the most thermodynamically stable complexes undergoing the slowest rate of hydrolysis. More recent measurements using high copper(II) to ligand ratios have indicated that the copper(II)-imine is quite stable to hydrolysis at pH 5. [Pg.460]

The tetrameric Zr complexes [Zr(0H)2(H20)2L]4X8 (L = bipyridyl, phenanthroline, various Schiff-bases X = Cl, NCS) were the presumed products from the reaction of ZrOCl2 with various heterocyclic bidentate ligands.336 The interaction of H20 with Zr0(C104)2 or Zr0(N03)2 was probed by NMR spectroscopy.337,338 In the latter case, the cation [Zr4(0H)8(H20)i6]8+ (80) was proposed as the product.338 The related trimer [Zr02Ci2H8(/u2-0H)]3(//3-0)Li5(THF)g(H20)5 (81) was isolated from the hydrolysis product of an organometallic precursor. X-ray structural data confirmed the planarity of the six-membered Zr3(/r2-OH)3 core.339 In related work, protometric studies of Zr hydroxide complexes have probed thermodynamic stability,340 while FT IR and theoretical investigations have addressed the details of laser-ablated group IV metal atoms that... [Pg.128]


See other pages where Schiff base ligands hydrolysis is mentioned: [Pg.846]    [Pg.892]    [Pg.902]    [Pg.85]    [Pg.164]    [Pg.448]    [Pg.75]    [Pg.297]    [Pg.440]    [Pg.64]    [Pg.64]    [Pg.72]    [Pg.35]    [Pg.261]    [Pg.205]    [Pg.35]    [Pg.444]    [Pg.177]    [Pg.115]    [Pg.1165]    [Pg.613]    [Pg.431]    [Pg.205]    [Pg.325]    [Pg.177]    [Pg.361]    [Pg.79]    [Pg.177]    [Pg.752]    [Pg.1075]    [Pg.1090]    [Pg.460]    [Pg.189]    [Pg.198]    [Pg.126]    [Pg.1982]    [Pg.251]    [Pg.111]    [Pg.265]    [Pg.152]    [Pg.188]   
See also in sourсe #XX -- [ Pg.43 , Pg.44 ]




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Ligand-based

Ligands hydrolysis

Schiff bases hydrolysis

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