Hydroxyquinoline Reagent

Acetic acid - 8-hydroxyquinoline reagent - dissolve 10 g 8-hydroxy-quinoline in a solution of 2.5 % (v/v) acetic acid and make up to 1 I. (The 8-hydroxyquinoline blocks the readsorption or precipitation of phosphate by active iron and aluminium during acetic acid extraction. Synonyms hydroxybenzopyridine oxine phenopyridine 8-quinolinol. Not carcinogenic, but may be harmful if swallowed, and causes irritation to eyes, respiratory tract and skin safety data sheet at http //www. jtbaker.com/msds/q7250. htm.)... 

Procedure (extraction). Transfer 2.5 g air-dry soil, 2 mm mesh size, into a 250 ml polypropylene screw-cap centrifuge bottle/tube and add 100 ml acetic acid - 8-hydroxyquinoline reagent. Cap the tube and shake overnight (17 h) on a reciprocating shaker, at approximately 275 strokes of 25 mm length per minute at a constant temperature (20°C). Centrifuge for 15 min at 2800 rpm and remove an aliquot for the determination of acid extractable inorganic phosphorus (a). 

When Al is alloyed with Mg(as for use in some incendiary, tracer of photoflash compns), the tests and detns for such alloys include a)Granulation, using US Std sieves b) Moisture, by drying in a vacuum desiccator over HjSO for 24 hrs c)Grease wd ftus, by extraction with ether d)Aluminum, using 8 hydroxyquinoline reagent e)Mag-... 

Selectivity of solvent extraction may be improved by using masking agents such as fluoride or cyanide ions in connection with 8-hydroxyquinoline. 8-Hydroxyquinoline reagent solution is prepared in an organic solvent (chloroform, butanol, ethylacetate, MIBK). 

Colorimetric methods always include hafnium. Most methods employ a separation step such as solvent extraction. The three reagents used successfully are 8-hydroxyquinoline (88), alizarin red S (89), and catechol violet (90). 

Colorimetric methods have been successfully used for determining trace amounts of ethanol. Ammonium hexanitratocerate(IV) has been used as a reagent (262) and for continuous automatic analysis. Alcohols form colored complexes with 8-hydroxyquinoline and vanadic compounds. The absorbance of these complexes, measured at 390 p.m has been used to provide an analytical procedure (263). 

Coulometric determination of Cu(II) and Ni(II) was canied out applying such reagents as 8-hydroxyquinoline and 8-mercaptoquinoline. Electrogenerated bromine was used as a titrant. 

Note The reagent can be employed on silica gel layers, which may also be impregnated, for example, with 8-hydroxyquinoline or dibenzoylmethane [3] or with 2,2 -dipyridyl or iminodiacetic acid [4] or on cellulose layers. 

The yield of hydroxylated products is always very low, and there are usually a number of by-products. For instance, side chains of aromatic nuclei are easily attacked, as shown by the formation of 5-hydroxymethyluracil from thymine. Breslow and Lukens measured both the amount of 3-hydroxyquinoline formed and the quinoline consumed during hydroxylation with Fenton s reagent and EDTA in the presence of several adducts (Table XII). 

Hydroxyquinoline, having both a phenolic hydroxyl group and a basic nitrogen atom, is amphoteric in aqueous solution it is completely extracted from aqueous solution by chloroform at pH < 5 and pH > 9 the distribution coefficient of the neutral compound between chloroform and water is 720 at 18 °C. The usefulness of this sensitive reagent has been extended by the use of masking agents (cyanide, EDTA, citrate, tartrate, etc.) and by control of pH. 

Hydroxyquinoline is an almost colourless, crystalline solid, m.p. 75-76 °C it is almost insoluble in water. The reagent is prepared for use in either of the following ways. 

Nitrates and nitrites are first reduced to nitrosyl chloride with thionyl chloride. The volatile nitrosyl chloride then reacts with 4-aminobenzenesulfonic acid to yield a diazonium salt that then couples with 8-hydroxyquinoline to form a colored azo compound. Hence, the coupling reagent is applied to the chromatogram first. 

Chloranils, which are formed from polychlorine phenols by heating briefly with cone, nitric acid, can be detected, without chlorine treatment, with TDM reagent, followed by heating (10 min 110°C) [3]. Phenols yield variously colored chromatogram zones (e.g. phenol mauve, chromotropic acid grey, 8-hydroxyquinoline light brown, 4-/ert-butyl-pyrocatechol red [1]). 

Methyl-8-hydroxyquinoline, 7 588 10-Methyl-9-acridinium carboxylate, chemiluminescence reagent, 5 846 Methyl abietate, 24 553 Methyl acetate... 

The use of complexing reagents containing two functional groups is an effective method employed for metal ion determination by fluorescence measurement. For example, 8-hydroxyquinoline (3) (Figure 4.8) forms complexes with a large number of metal ions. 

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