Salicylaldehyde, Schiff base with

Kinetics of the reaction of certain Mo02L complexes (L = S-containing salicylaldehyde Schiff base) with PEtPh2 also show the reactions to be first order in complex and in phosphine,145-147,168 The rate constants depend upon the substituent on the aromatic (salicylaldehyde derived) ring and correlate with reduction potentials of the complexes.145... 

Salicylaldehyde, Schiff base with, 99 Salmonella typhi, 152 Salts, of acetamido thiazoles, 91 Sandmeyer reaction, in halothiazoles synthesis, 12... 

H2acac2trien of triethylenetetramine with salicylaldehyde Schiff base obtained from the 1 2 condensation... 

Template and capping reactions feature in recent work. A number of sterically hindered H20 and N4 ligands have been prepared in which a quadridentate Schiff base is capped by condensation of salicylaldehyde or pyrrole-2-carbaldehyde with a series of bis(8-aminonaphthyl)alkyl ethers. These ligands combine the versatility of the Schiff base with the protective features well known for certain model porphyrin systems, and appear to be of some interest. The zinc(II) complex and other transition metal complexes have been prepared.340... 

It is well over 40 years since Pfeiffer discovered that certain reactions of a-amino acid esters, in particular, ester exchange, racemization and oxygenation, are effected very readily when their Schiff bases with salicylaldehyde are complexed to a transition metal ion (most notably Cu11). The Schiff bases result from a condensation reaction between a reactive carbonyl group and the amino group of the amino acids. Snell and his co-workers43 were also one of the first to point out that similar reactions also occurred if pyridoxal was used instead of salicylaldehyde, and that there is a close analogy with pyridoxal phosphate-promoted enzymic reactions of a-amino acid metabolism. Since then much work has been due on these and other similar systems and their reactivities. 

Grafting on polymers to obtain functional groups for binding of metal ions has been reported polyethylene-graft-poly(methylvinylketone)/Schiff base with 2-aminophenol 38 [1,107] or salicylaldehyde hydrazide [108] (for other grafted ligands see [109]). 

The recycling of the undesired enantiomer from the enzymatic resolution is of crucial importance particularly on an industrial scale [107]. The classical chemical method consists of the thermal racemization of an amino acid ester at about 150-170°C. Milder conditions can be employed for the racemization of the corresponding amides via intermediate formation of Schiff bases with aromatic aldehydes such as benzaldehyde or salicylaldehyde (Scheme 2.14). More recently, intense research has been devoted to the use of isomerase enzymes (such as amino acid racemases [108]) aiming at the development of dynamic resolution processes. 

One method of solving the kinetics dilemma is well known in coordination chemistry that is, start with a labile metal ion and render it inert during the course of the synthetic reaction. We have accomplished this in the case of zirconium(IV) by starting with tetrakis(salicylaldehydo)zirconium(IV), which is quite labile, and polymerization with 1,2,4,5-tetraaminobenzene in a Schiff-base condensation reaction in situ (6). The polymeric product contains a "double-headed" quadridentate ligand, which is much more inert to substitution. However, 1,2,4,5-tetraaminobenzene has become very expensive. Therefore, the synthesis of a zirconium polymer with 3,3, 4,4 -tetraaminobiphenyl (commercially 3,3 -diami nobenzidine) with zirconium salicylaldehyde, Zr(sal)4 (7) has been undertaken as shown below ... 

In contrast with the Schiff base salen, salicylaldehyde oxime (79) (salox) complexes of Co have received comparatively little attention, but a series of bis-bidentate divalent complexes of the form iraiis-Co(sa 1 ox)2( D M SO)2 have been reported.343 The heterocyclic bidentate oxime violurate (lH,3H-pyrimidine-2,4,5,6-tetrone 5-oximate, Hvi) (80) and its /V-methyl (mvi) and /V,/V -dimethyl (dmvi) derivatives form high-spin divalent [Co(vi)]+ and Co(vi)2 complexes, whereas [Co(vi)3] is low spin.344 The mixed-ligand Co(dmvi)2(phen) complex is also low spin. The crystal structure of m-Co(pxo)2Br2 (pxo = 2-acetylpyridine-l-oxide oxime) is isostructural with the Ni11 relative.345 The dichloro complex also adopts a cis configuration. The tridentate dioximes 2,6-diformyl-4-methylphenol dioxime and 2,6-diacetyl-4-methylphenol dioxime (Hdampo) form binuclear complexes of the type (81a) and (81b) respectively.346 Cobalt oxide nanoparticles were prepared by... 

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... 

Schiff bases provide useful mixed donor sets. The carbonyl function of the most frequently used ligands is derived from either 1,3-dicarbonyl compounds or salicylaldehyde. Favourable combinations involve O-, N- and S-donor atoms. A range of technetium and rhenium complexes exist with bi-, tri-, tetra- and pentadentate ligands. The geometry of these complexes depends on the number and type of coordinating atoms as well as on the chain length between the donor atoms in the SchifF-base ligands. 

Methyltrioxorhenium(VII) (MTO) forms mono- or bis-complexes with di-Schiff bases being derivatives of various salicylaldehydes and fra s-l,2-diaminocyclohexane [37] 90... 

In a systematic study of the effects of variation of the tetramine involved in formation of the hexadentate N402 donor Schiff base the linear 3,3,3-, 3,2,3-, 2,3,2- or 2,2,2-tetramines, where the numbers refer to the number of carbon atoms between the amine groups (note 2,2,2-tetramine is synonymous with the nomenclature trien used previously) have been condensed with salicylaldehyde, acetophenone or benzophenone [206]. Crystal struc-... 

Aromatic aldehydes react with primary amines forming Schiff s bases which are often coloured. The colour may then be used to quantitate the amine. Using this principle Kocyl has shown neomycin to form a yellow-coloured Schiff s base with salicylaldehyde though the quantitative aspect of this procedure is, as yet, incomplete. 

The new series of oxovanadium(iv) complexes with Schiff bases derived from 2-aminothiophenol and substituted salicylaldehyde (40) or 2-hydroxy-naphthaldehyde has been synthesized and characterized. The ligands (40a),... 

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