9- -2,3,7-trihydroxy-6-fluoron

Turchini and Gosselin de Beaumont" reported the use of 9-phenyl-(or 9-methyl-) 2,6,7-trihydroxy-3-fluorone for the differential staining of ribo- and desoxyribo-nucleic acids. The former gives rise to a yellow-pink color and the latter to a bluish-violet tint. It is necessary to hydrolyze the nucleic acid since it is the pentoses thereby liberated which yield the color, indicating that the reagent differentiates between ribose and its 2-desoxy analogue. 

Co (II) 2,6,7 -trihydroxy-9 - (4 -chlorophenyl) -3-fluorone-H202-Co(II) Alkaline medium HTAB... 

The sensitivity and the selectivity of the methods involving 2,3,7-trihydroxy-6-fluorones increase markedly in the presence of surfactants [67]. 

In addition to phenylfluorone, a number of other 2,3,7-trihydroxy-6-fluorones have been recommended for determination of germanium. Disulphophenylfluorone (e = 9.0-10" ) reacts under the conditions similar to those of fluorone [29]. Some trihydroxyfluorones react with Ge in the presence of antipyrine and bromide (also f, SCN, and CIO4) to form compounds extractable with CHCI3 or similar solvents [30]. The sensitivity of determining Ge with various fluorones increases in the presence of cationic surfactants. The following systems have been recommended salicylfluorone with CP (e = 1.2-10 at 530 nm) [31], tetrabromo-salicylfluorone with CP (e = 1.3 10 at 520 nm) [32], and o-chlorophenylfluorone with CTA (e = 1.8-10 at 516 nm [33]). A non-ionic surfactant Triton X-305 has been used in the case of disulphophenylfluorone [34]. 

Methods for determining molybdenum with use of 2,3,7-trihydroxy-6-fluorones are highly sensitive. o-Nitrophenylfluorone is especially recommended [78-80]. In the presence of DAM (dlantipyrylmethane), a chloroform-extractable ternary compound is formed with e = 1.30-10 [78]. Other fluorones used include phenylfluorone (formula 22.1) [81-86], propylfluorone, salicylfluorone, and methylfluorone [87-89]. 

Among 2,3,7-trihydroxy-6-fluorones, the best results in the determination of Nb were obtained with phenylfluorone and o-nitrophenylfluorone (e = 1.3-10 - 1.7-10 ) [69-71]. A very sensitive method has been based on a mixed complex of Nb with o-nitrophenylfluorone and DAM (e = 1.9-10 ) [72]. Even higher sensitivity (e = 2.1 -10 ) has been obtained with the... 

Some 2,3,7-trihydroxy-6-fluorones are sensitive reagents for Ta, e.g., phenylfluorone [103], salicylfluorone [104,105], and 9-(2 -hydroxyphenyl)-2,3,7-trihydroxy-6-fluorone (e = 2.110 at 505 nm) [106]. High sensitivity (e = 1.6-10 -1.8-10 ) has been obtained in the presence of surfactants [105]. This method has been used for the determination of tantalum in niobium metal. Tantalum has been determined with the use of 4,5-dibromo-o-nitrophenylfluorone [107]. 

Phenyl-3-fluorone (2,6,7-trihydroxy-9-phenylxanthen-3-one) [975-17-7] M 320.3, m >300 (dec), 350°, Xmax462nm (e 4.06 x 10, in IM HCl aqueous EtOH). RecrystalUse it from warm, acidified EtOH by addition of ammonia. The crude material (Ig) can be extracted with EtOH (50mL) in a Soxhlet apparams for lOhours to remove impmities. Impurities can be detected by paper electrophoresis. The triacetate forms yellow needles from EtOH (m 230-233°). [Petrova et al. Anal Lett 5 695 1972, Beilstein 18 H 199, 18 1404,18 III/IV 2824.]... 

Antimony salts, in acid solution, react with aromatic o-dihydroxy compounds (e.g., p3n ocatechol, pyrogBllol) to produce slightly soluble, white, or light yellow crystalline precipitates which can be formulated as cyclic esters of antimonous acid. The yellow dyestuff 9-methyl-2,3,7-trihydroxy-6-fluorone (I), which can be viewed as a derivative of pyrocatechol, forms a red antimonous compound (II). 

Test with 9-phenyl-2,3 7-trihydroxy-6-fluorone (phenyl fiuorone) ... 

A pink precipitate or coloration is produced by the action of acid solutions of alkali germanates with the yellow alcohol solution of 9-phenyl-2,3,7-trihydroxy-6-fluorone (I). The composition of the reaction product is not known. In view of the phenolic nature of the dyestuff serving here as reagent, the possibility of ester formation as indicated by (II) is not excluded. Consideration must also be given to the production of an adsorption compound (color lake)2 between GeOa aq and (I). 

Reagent 0.06 % solution of 9-phenyl-2,3,7-trihydroxy-6-fluorone in 95 % alcohol, acidified with one drop oi % N hydrochloric acid. The solution is stable. 

Methoxy-4, 5 -methylenedioxy-2 -ethyl-p-methylaminopheny[)-2,3,7- trihydroxy-6-fluorone... 

Dibromo-3 4 5 6 -tetrahydroxyspiro[isobenzofuran-l 3 ) 9 9Y ]xantheri -3-one, 9CI. 2J-Dibromo-3,4,5-trihydroxy-9-(2-carboxyphenyl)-6-fluorone [35236-70-5]... 

Bromo-2-hydroxyphenyl)-2,6,7-trihydroxy-3//"Xanthen-3-one, B-00513 A -(4-Bromophenyl)-A -hydroxy-3-(2-thienyl)-2-propenamide, B-00552 1 -[(5-Bromo-2-pyridinyl)azo]-2-naphthalenol, B-00573 Cacotheline, C-00005 9-(2-Carboxy-4-pyridyl)fluorone, C-00043... 

Phenylfluorones are a variety of chelating xanthene molecules which form sparingly soluble coloured complexes with certain inorganic species. Phenyl-fluorone (2,6,7-Trihydroxy-9-phenyl-3H-xanthen-3-one) itself, for example, forms a reddish suspension with Ge(/V0, Ga(//7), Sn(iy), SB(//7) and other species. The coloured suspensions can be stabilized with a protective polymer such as poly(vinyl alcohol) for spectrophotometric measurement. 

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