Quinaldic acids

Polymers containing 8-hydroxyquinoline appear to be selective adsorbents for tungsten in alkaline brines (95). In the presence of tartrate and citrate, quinaldic acid [93-10-7] allows the separation of zinc from gallium and indium (96). Either of these compounds can selectively separate lead and zinc from oxide ores as complexes (97). It is also possible to separate by extraction micro quantities of rhenium(VII), using quinoline in basic solution (98). The... 

Some acids such as cinnamic, lactic, oxalic and quinaldic acid yield yellow zones. Maleic, fumaric and o-phthalic acids turn red in color, salicylic acid grey and 4-aminobenzoic acid bluish. 

Nicolaou in his model system for an approach to the thiopeptide antibiotic thiostrepton, in particular, the elaboration of the quinaldic acid moiety. The tetrahydroquinoline 21 was converted to the A-oxide by /n-CPBA oxidation. Subsequent treatment with TFAA, to carry out the Boekelheide reaction, was followed by hydrolysis of the resultant ester to produce 22 as a mixture of alcohols. 

Determination of cadmium as quinaldate Discussion. Quinaldic acid or its sodium salt precipitates cadmium quantitatively from acetic (ethanoic) acid or neutral solutions. The precipitate is collected on a sintered-glass crucible, and dried at 125 °C. A determination may be completed in about 90 minutes. For the limitations of the method, see Section 11.11(G). 

Quercitrin 149, 279, 280, 323 Quinaldic acid 171 Quinine alkaloids 88 Quinine, pH-dependent change of fluorescence color 91 Quinoline alkaloids 66... 

For biosynthetic studies of the formation of the macrocyclic peptide antibiotic thiostrepton, isotopically labeled [ C]-AAs were employed. The quinaldic acid moiety 97 of this antibiotic was shown to be biosynthesized from 3-methyltryptophan, and a mechanism has been proposed (93JA7992). 

Fig. 26. Pyridme-di(monothiocarboxylic acid) (73), thioquinaldic (74), quinaldic acid (75)...

From iron-deficient cultures of Pseudomonas fluorescens, 8-hydroxy-4-methoxy-monothioquinaldic acid (thioquinolobactin) together with the corresponding quinaldic acid (quinolobactin) (Fig. 26, 74 and 75), could be isolated (258). Quinolobactin can act as an alternative siderophore of Pseudomonas fluorescens (245), although it is the hydrolysis product of the thioacid (220). Its synthesis and complex formation as (Fe )Lig2 was described (9S). 

Mixed donor ligands. The complex [FeL3]Cl3 (L = acetylhydrazine) contains the ligand in its bidentate form, bonded via the carbonyl and primary amino-groups.Pyridine-2-carboxaldehyde and l,l,l-tris(aminoethyl)ethane react with Fe" via a template reaction to form [Fejlpyljltame) ], in which three molecules of carboxaldehyde have condensed with one molecule of triamine to produce (pyljltame). MeC(CH2N=CH-oc-py)3 the complex cation is octahedral. The complexes [FeL ] (L = l,10-phenanthroline-2-carboxamide, n = 1 or 2) have been isolated they are both six-co-ordinate. Very weak d-d bands have been identified in the spectra of complexes of ot-picolinic acid and quinaldic acid with Fe". ... 

Each of the methods had trouble recovering the more highly water-soluble or volatile model compounds such as trimesic acid, furfural, glucose, glycine, caffeine, and methyl isobutyl ketone. Quinaldic acid, an amphoteric substance of moderate water solubility, was also poorly recovered by each method, except for the QXAD-4 procedure. 

Preparation of Model Compound Test Solutions. Individual stock solutions containing 500 mg/L were prepared by dissolving quinaldic acid, glycine, and glucose in OFW 5-chlorouracil in 2 N NH4OH phenanthrene, 1-chlorododecane, 2,4 -dichlorobiphenyl, and 2,2, 5,5 -tetrachlorobiphenyl in hexane and the remaining compounds in methanol. Humic acid stock solution was prepared in 0.02 N NaOH. The composition of the test solutions is reported in Table I. Test solutions (500 mL) were prepared by adding salts and the required volumes of stock solutions in OFW. Phenanthrene, 1-chlorododecane,... 

Hydrophilic Base Fraction. An aliquot (1-2 mL) of the hydrophilic base fraction was dried under a stream of N2, acidified with HC1, and analyzed for glycine after derivatization with isoamyl alcohol, acetyl chloride, and hep-tafluorobutyric anhydride according to the procedure described by Burleson et al. (23). An aliquot (1-2 mL) of the same hydrophilic base fraction was analyzed for quinaldic acid following the procedure mentioned for the hydrophobic acid fraction. The remaining portion of the hydrophilic base fraction was extracted at pH 10 with 50 mL of methylene chloride. The extract was concentrated to 1 mL and analyzed by GC-FID and GC-MS. 

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