L-Phenyl-3-methyl-5-pyrazolone

When ethyl acetoacetate is warmed with an equivalent quantity of phenyl-hydrazine, the compound (I), which is not a true hydrazone, is first formed this undergoes ring formation (II) with loss of ethyl alcohol upon further heating. The product (II) is N or l-phenyl-3-methyl-5-pyrazolone. 

In mordant dyes, phenols, naphthols, and enolizable carbonyl compounds, such as pyrazolones, are generally the couplers. As a rule, 2 1 metal complexes are formed ia the afterchroming process. A typical example of a mordant dye is Eriochrome Black T (18b) which is made from the important dyestuff iatermediate nitro-l,2,4-acid, 4-amiQO-3-hydroxy-7-nitro-l-naphthalenesulfonic acid [6259-63-8]. Eriochrome Red B [3618-63-1] (49) (Cl Mordant Red 7 Cl 18760) (1, 2,4-acid — l-phenyl-3-methyl-5-pyrazolone) is another example. The equiUbrium of the two tautomeric forms depends on the nature of the solvent. 

An interesting report on l-phenyl-3-methyl-5-pyrazolone (49) shows that when two tautomers are of comparable energy they could both be present in the crystal cell (73CSC469). In this case NH and OH tautomers, (49a) and (49b) respectively, coexist in the crystal (Section 4.04.1.5.2). 

The classic example of this group is l-phenyl-3-methyl-5-pyrazolone (12.60), which was mentioned previously. The question of whether this compound and its derivatives react as enols or ketones, which was fervently discussed in former years, is now irrelevant, since it is known that normally only the mutual conjugate base of enol and ketone in the equilibrium (Scheme 12-33) participates in the actual substitution step. 

The diazotized 3-amino-4-phenylpyrazolo[3,4- ]pyridine-5-carbonitrile 698 coupled with l-phenyl-3-methyl-5-pyrazolone 699 to yield 700, which cyclized (91G209) to the condensed pyrazolotriazine 701. 

Suzuki, S., Ishida, Y., Arai, A., Nakanishi, H., and Honda, S. (2003). High-speed electrophoretic analysis of l-phenyl-3-methyl-5-pyrazolone derivatives of monosaccharides on a quartz microchip with whole-channel UV detection. Electrophoresis 24, 3828—3833. 

Heterocyclic azo couplers have also featured prominently in disperse dye chemistry, especially in the production of yellows. Cl Disperse Yellow I (B-71MI11202) is in fact an azo dye prepared from benzenediazonium chloride and l-phenyl-3-methyl-5-pyrazolone, and pyrazolone couplers continue to appear in patents. However, the most important recent development has been the introduction of 2,6-dihydroxypyridine couplers in azo dyes such as (54). Although the couplers had been disclosed some time ago, their development by... 

An alternative approach, which additionally favors the separation of sugars from interfering compounds, is the precolumn formation of the derivatives in this case trace sugar detection is sometimes possible, as nmol or pmol orders are approached. Examples include the use of dan-sylhydrazine (with either fluorimetric or colorimetric detection) (39) and l-phenyl-3-methyl-5-pyrazolone (UV absorption or electrochemical detection) (40). 

Diazo Components With Cycloammonium Groups. Polynuclear N heterocycles that carry an amino group in the carbocyclic aromatic ring can be diazotized and then joined to azo dyes by using aromatic or heterocyclic coupling components. Quatemization at the heterocyclic nitrogen atom may occur before or after coupling. The azo dye 43, from 2-methyl-5-aminobenzimidazole and l-phenyl-3-methyl-5-pyrazolone, used in the form of its hydrochloride, dyes paper and leather in clear yellow shades [130],... 

Reaction of chlorosulfonic acid with mono- [141] or disazo dyes [142] yields sulfonyl chlorides, which can then be transformed into cationically substituted sulfonamides by reaction with dialkylaminoalkylamines. The coupling product of diazotized 2-anisidine with 2-hydroxynaphthoic acid arylide upon such treatment dyes paper red, and the azo dye from tetrazotized dianisidine and l-phenyl-3-methyl-5 -pyrazolone gives yellowish orange shades. 

C.I. Solvent Yellow 82, [12227-67-7], similar to C.I. Solvent Yellow 21, [5601-29-6], 18690, which is a 1 1 chromium complex of the azo dye obtained from anthranilic acid and l-phenyl-3-methyl-5-pyrazolone. 

Aldopentoses (as l-phenyl-3- methyl-5-pyrazolone derivatives) Nucleosil silica, in-column 3-aminopropylated or Devosil NH2, 3 pm (25 mM HEPES-NaOH, pH 6.0)-acetonitrile (2 1) 345 mm x 100 pm i.d. 250 mm effective length 41 ... 

Stfirba et al. were successful, however, in solving that problem for another azo coupling component, namely l-phenyl-3-methyl-5-pyrazolone 119), which in solution exists as a mixture of tautomeric forms A-C. The conjugate base 120 reacts 10 times faster than the neutral compound. 

The next category of f)-diketones are 4-acyl-l-phenyl-3-methyl-5-pyrazolones (see Eigure 2.5) and their analogs of 3-phenyl-4-acyl-5-isoxazolones (see Eigure 2.6). The latter type of P-diketones have stronger acidities (lower pA a values) than the former, and have recently been smdied as promising light conversion molecular devices [46-51]. 

Remya, P.N., Biju, S., Reddy, M.L.R, et al. (2008) ID Molecular ladder of the ionic complex of terbium-4-sebacoylbis(l-phenyl-3-methyl-5-pyrazolonate) and sodium dibenzo-18-crown-6 synthesis, crystal structure, and photophysical properties. Inorganic Chemistry, 47, 7396-7404. 

Various aromatic amines, phenols, and compounds containing active methylene groups can be titrated with arenediazonium salts, from which 4-bromo-l-naphthale-nediazonium chloride seems to be the most widely applicable titrant. Compounds that react slowly with arenediazonium salts can be determined by back-titration when the excess of arenediazonium salt is back-titrated with either sodium tetraphenylborate or 2,4-diaminotoluene. Indirect determination is useful for secondary amines, which react with arenediazonium ions to form triazenes. The determination of diazonium salts of ampholytic character is based on the reaction of these salts with l-phenyl-3-methyl-5-pyrazolone, the excess of which is titrated with 4-bromo-l-naphthalenediazonium chloride solution. 

The derivatization of aldehydes in reducing carbohydrates can also be performed by a condensation reaction between the active hydrogens of l-phenyl-3-methyl-5-pyrazolone (PMP) and the aldehyde functionality under slightly basic condition. The formed bis-PMP derivatives can be separated by CZE and detected by UV absorbance. Oligosaccharides can also be separated as complexes with a variety of compounds, including acetate, molybdate, germanate, stannate, arsenite, wolfra-mate, vanadate, and tellurate of various alkali and alkaline... 

N-Protection in peptide synthesis. Diketene reacts with an amino ester hydrochloride in ethanol at 0-5° in the presence of 1 equivalent of sodium ethoxide or a tertiary amine to give the often crystalline and easily purified N-acetoacetyl derivative (1). After peptide synthesis the protective group is removed by treatment with phenylhydrazine, which affords l-phenyl-3-methyl-5-pyrazolone. 

Wu X, Yang JH, Sun SN, et al. Determination of nucleic acids based on the quenching effect on resonance light scattering of the Y(III)-l,6-bi(l,-phenyl-3,-methyl-5,-pyrazolone-4 -)hexanedione system. Luminescence 2006 21 129-34. 

Honda S., Akao E., Suzuki S., Okuda M., Kakehi K., Nakamura J., High-performance liquid chromatography of reducing carbohydrates as strongly ultraviolet-absorbing and electro-chemically sensitive l-phenyl-3-methyl-5-pyrazolone derivatives. Analytical biochemistry 180 (1989) 351-357. 

In a similar way, pyrimido[4,5-< ][l,2,4]triazin-6,8-diones, bearing the alkylsulfonyl group, undergo the nucleophilic displacement reaction by action of malonodinitrile, indole, and l-phenyl-3-methyl-5-pyrazolone <1998RJ0297, 2003KFZ20, 2003PCJ238>. 

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