Phenylazo-pyrazoles

Tartrazine was separated by ion-pair HPLC from its subsidiary dye 3-carboxy-5-hydroxy-1 -p-sulfopheny-4-phenylazo-pyrazole disodium salt (195) and from its intermediates sulfanilic acid and l-(4-sulfophenyl)-3-carboxy-5-hydroxypyrazolone (pyrazolone-T) by means of TBA hydroxide (194,212). Ion-pair chromatography was also used for the determination of free and bound nonsulfonated aromatic amines in tartrazine after reduction with dithionite, diazotization with sodium nitrite, and coupling with R-salt (202). 

Dougan SJ, Melchart M, Habtemariam A, Parsons S, Sadler PJ (2006) Phenylazo-pyridine and phenylazo-pyrazole chlorido ruthenium(II) arene complexes arene loss, aquation, and cancer cell cytotoxicity. Inorg Chem 45 10882-10894... 

Synonym 3-Methyl-1 -phenyl-4-(phenylazo)-pyrazol-5-ol Source Tamura, K. Shinoda, T. Fluid Phase Equil. 2004), 219(1), 25-32. 

Formation of Pyrazoles from Bis(hydrazones).—Mesoxaldehyde bis(phenylhydrazone) (193), obtained by periodate oxidation of saccharide osazones (192) is readily cyclized in the presence of acids to give l-phenyl-4-phenylazo-pyrazole (195).162 365 Hexulose phenylosazones (192) are also disproportionaled in the presence of acidic salts of carbonyl reagents, such as hydroxylamine hydrochloride, to give l-phenyl-4-phenylazo-pyrazolin-5-one (196). The reaction probably proceeds via mesoxalic acid 1,2-bis(phenylhydrazone) (194).365 The hydroxalkyl derivatives of 196 are produced from dehydroascorbic acid bis(phenylhydrazone) by treatment with base to open the lactone ring and permit the conversion of 197 to 199.351,366 Another type of pyrazole that is formed by dehydrating osazones with acetic anhydride is discussed later under anhydroosazones (see Schemes 45,53). 

Sadler has focused on the synthesis of novel (arene)Ru(II) complexes with phenylazo-pyrazoles (Fig. 21.18) and on their cytotoxicity toward A2780 human ovarian or A549 human lung cancer cells. 

Figure 21.18 (Arene)Ru(II) complexes with phenylazo-pyrazoles.

Pyrazol-5-one, 3-methyl-1 -phenyl-4-phenylazo-methylation, 5, 264 Pyrazol-5-one, pyridyl-biological activity, 5, 295 Pyrazol-5-one, l-(4 -carbamoylphenyl)-3-methyl-azo pigments from, 1, 334 Pyrazol-5-one, 3-methyl-l-phenyl-azo dyes from, 1, 330 azo pigments from, 1, 334 Pyrazolones acetylated acylotropy, 5, 264 analytical applications, 5, 300 anions... 

Bromophenylazo)-2-propyl hydroperoxide, 3156 l,2-Dihydroperoxy-l,2-bis(benzeneazo)cyclohexane, 3762 (Y-Phcnylazobcnzyl hydroperoxide, 3609 a-Phenylazo-4-bromobenzyl hydroperoxide, 3607 1-Phenylazocyclohexyl hydroperoxide, 3539 a-Phenylazo-4-fluorobenzyl hydroperoxide, 3608 3,3,5-Triphenyl-4,4-dimethyl-5-hydroperoxy-4,5-dihydro(3H)pyrazole, 3841... 

Aryl(Hetaryl)aminosul-fonyl-phenylazo -5-methyl-I-( 4-methyl-phenyl)-3-(2,4,6-trimethoxy-phenyl) -pyrazol 68-80 1... 

S02-NH-Ar ch3 och3 0 cH3 —< J -N02 co-c6hs c6h, 4 Aryl( Hetaryl) aminosulfonyl-phenytazo]-1-benzoyl-5-meth-yl-3-(4-methyl-phenyl)-pyrazol 4- [A ryl( Hetaryl) aminosulfonyl-phenylazo -5-( 4-methoxy-phenyl) -3- (4-nitro-phenyl)-l-phenyl-... 71-78 68-74 1 2... 

Replacement of a halogen atom in the 5-position of a pyrazole by nucleophiles is facilitated by the presence of an electron-withdrawing substituent, such as the phenylazo group, in the 4-position, where the halogen may be replaced by amino, alkylamino, dialkylamino, arylamino, sulfhydryl, and other such groups.664-660... 

Sum of 4,5-Dihydro-5-oxo-l-phenyl-4-[(4-sulfophenyl)-azo J-lH-pyrazole-3-carboxylic Acid, Disodium Salt, and 4,5-Dihydro-5-oxo-4- (phenylazo )-l-(4-sulfophenyl )-lH-pyra-zole-3-Carboxylic Acid, Disodium Salt Not more than 0.5%. 

Butensaure 2-Chlor-3-phenylazo- -ethylester E15/1, 974 (aus 4,4-X2 — 5-oxo — 4,5-H2 — pyrazol) Imidazol 4-(4-Chlor-benzyl)-5,5-dimethyl-2-oxo-2,5-dihydro- -3-oxid E14b, 1432 (Amin-oxim/ COCl2)... 

Phenyl-hydrazino)-malonsaure-amid-nitril liefert mit Hydrazin-Hydrat ohne Losungsmittcl auf dem Wasserbad 3(5)-Amino-5(3)-hydroxy-4-phenylazo-1 H-pyrazol (95% Schmp. 238°)724. 

Phenylhydrazono-malonsaure-phenylhydrazonid wird durch lodsaure in 50%igem Ethanol bei 80° zu 5-Hydroxy-l-phenyl-4-phenylazo-1H-pyrazol (33% Schmp. 150°) oxidiert717 ... 

Ar = C(,h5 5-Hydroxy-3-hydroxymethyl-l-phenyl-4-phenylazo-lH-pyrazol 70% Schmp. 155u983... 

Bei Einwirkung von 1-Benzoyl-l-phenyl-hydrazin auf 4,5-Dioxo-3-methyl-l-phenyl-4,5-dihydro-l H-pyrazol entsteht unter Wanderung des Benzoyl-Restes zum O-Atom 5-Benzoyloxy-3-melhyl-l-phenyl-4-phenylazo-lH-pyrazol (Bd.X/2, S.473 (1967). 

Durch Nitrierung von 3,5-Dimethyl-4-(4-methyl-phenylazo)-l H-pyrazol mit einem Salpeter-saure-Essigsaure-Gemisch erfolgt ipso-Substitution der Arylazo-Gruppe durch die Nitro-Gruppe1957 (weiteres Beispicl s. Lit.1374,, 376). 

Methyl-2-(4-inethyl-phenyl)-4-phenyl-2,4-dihydro- (r = CHj-c H.,)178 Ei-a-25i4 2,91 g (0,01 mo ) 5-Amino-3-methyi-4-(4-methyl-phenylazo)-l-phcnyl-1 H-pyrazol werden in 10 m/ DMF mit 1 g (0,0052 mol) Kupfer(II)-acctat 1 h auf 90-95° erhitzt, dabei wird ein Luftstrom durch... 

Benzylamino-4-nitro- 663 5-Benzylamino-3-phenyl-4-phenylazo- 629 l-Benzyl-4-brom-3-(carboxy-methoxy)-4-mcthyl-5-oxo-4,5-dihydro- 707 l-Benzyl-5-carboxy- 620 l-Benzyl-3-(carboxy-methoxy)-4-methyl- 707 l-Benzyl-3-(l-carboxy-l-methyl-ethoxy)-4-chlor-aus 1 -Bcnzyl-4-chlor-3-hydroxy-1 H-pyrazol/ Natriumhydroxid/2-Hydroxy-l-methyl-1,1,1-trichlor-propan 651... 

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