4- Methyl-3-phenyl-2-pyrazolin-5-one

C10H9NO 2-hydroxy-4-methylquinoline 607-66-9 24.83 1.1516 2 19050 C10H10N2O 3-methyl-1-phenyl-2-pyrazoline-5-one 89-25-8 25.00 1.1646 2... 

Methyl-1-phenyl-2-pyrazolin-5-one 3-Methyl-1-phenyl-5-pyrazolone. See 1-Phenyl-3-methyl-5-pyrazolone... 

Phenyl-2-methyl-2-propanol. See Dimethyl benzyl carbinol 3-Phenyl-2-methyl-propen-2-ol-1. See Methylcinnamyl alcohol 1 -Phenyl-3-methyl-5-pyrazolone CAS 89-25-8 EINECS/ELINCS 201-891-0 Synonyms Cl developer 1 Developer Z 2.4-Dihydro-5-methyl-2-phenyl-3H-pyrazol-3-one 3-Methyl-1 -phenyl-2-pyrazolin-5-one 3-Methyl-1 -phenyl-5-pyrazolone Norantipyrine Norphenazone 1-Phenyl-3-methyl-5-oxo-2-pyrazoline 1-Phenyl-3-methylpyrazolone-5 5-Pyrazolin-5-one, 3-methyl-1-phenyl-5-Pyrazolone, 3-methyl-1-phenyl-Empirical C10H10N2O Formula C6HsNN C(CH3)CH2CO Properties Wh. to It. yel. powd. orcryst. sol. 10-50 mg/ml in DMSO, 95% ethanol, acetone si. sol. in benzene sol. < 1 mg/ml in water insol. in ether, petrol, ether m.w. 174.20 vapor pressure < 0.01 mm Hg (20 C) m.p. 127-130 C b.p. 287 C (105 mm) ref. index 1.637 (20 C)... 

The azo dyes were identified by elemental analysis and MS,IR and NMR spectra, and it was proved by the studies of tautomerism of the azo dyes with IR and NMR spectra that hydrazone form was predominant in the azo dyes. First,the absorption peak of 1660, 1600, 1560 and 1260 cm" in IR spectrum of 4- were all compatible with the absorption peak CO, Endo C N, Exo C—N and NH of hydra-zone, respectively, that were exactly identified on arylazo-3-methyl-1-phenyl-2-pyrazolin-5-one... 

C20H21N3O9, 4,5-Dimethoxycarbonyl-3-(2,3-0-isopropylidene- -D-erythrofuranosyl)-1-p-nitrophenylpyrazole, 42B, 176 C20H22N4O, 4-(4-N,N-Diethylaminophenylimino)-3-methyl-1-phenyl-2-pyrazolin-5-one, 37B, 122... 

Bis[p-(dimethylamino)phenyl] hydroxymethyl]-4-chloro-3-methyl-1 -phenyl-2-pyrazolin-5-one, B-00319... 

Sulfonation of 2- and 3-pyrazolin-5-ones occurs at position 4. Thus 3-methyl-1-phenyl-pyrazolin-5-one with 20% oleum at 10-15 °C yields the corresponding 4-sulfonic acid (304) (64HC(20)l). Higher temperatures cause sulfonation not only of the heterocycle but also of the phenyl group. Antipyrine treated with sulfuric acid and acetic anhydride yields (305). 

Substituted pyrazolin-5-ones have only three and -substituted pyrazolin-3-ones only two tautomers, since now the corresponding 19c and 19d structures are isomers. The calculations involved l-methylpyrazolin-5-one (PM3/6-3H-G, anions and cations), l-phenyl-3-methyl-2-pyrazolin-5-one (DFT, radical reactions) [97JPC(A)3769], and l-(2, 4 -dinitrophenyl)-3-methyl-2-pyrazolin-5-one [B3LYP/6-31G and the crystal structure (Section V,D,2)] (98NJC1421). 

Chlorine-pyrazolinone-cyanide An equal volume mixture of 0.2 M 1 -phenyl-3-methyl-2-pyrazolin-5-one solution (in pyridine) and 1 M aqueous potassium cyanide solution is sprayed on the plate that has been previously exposed to chlorine vapors. The resulting red spots turn blue after a few minutes. 

The reaction of zinc with 2,3-dimethyl-l-phenyl-3-pyrazolin-5-one has been reported by Knorr807 to give benzene, aniline and unidentified products. Heymons and Rohland647 treated l,2-diphenyl-3-methyl-3-pyrazolin-5-one with metallic sodium, obtaining addition of sodium at the 1,4-position of the conjugated system present (eq. 132). 

Presumably the linking group is >NCH—N<. Bisamides of l-(amino-phenyl)-2-pyrazolin-5-ones and of 3-amino-2-pyrazolin-5-ones have been used. l-(3-Aminophenyl)-3-methyl-2-pyrazolin-5-one reacts with many aldehydes and ketones to form polymers.964 Probably condensation occurs at C-4 and the amino group. The product of reaction of p-cresol with formaldehyde has been found to react with 1-(4-hydroxy -phenyl)-3-methyl-2-pyTazolin-5-one to give a polymer that must have the aromatic and pyrazolinone rings connected by ether linkages.1269... 

Only half-a-dozen of these compounds are known (Table XLI) and at least this number of methods of preparing them have been reported. Borsche and Manteuffel125 have found that 2-pyrazolin-4,5-diones are formed as the by-products when oc-ketoesters are treated with aryl-diazonium salts. The principal products are 4-arylazo-2-pyrazolin-5-ones. Nitric acid oxidation of 3-methyl-l-phenyl-2-pyrazolin-5-one forms the corresponding 4,5-dione.809 Wislicenus and Gtiz1842 heated 4 -bromo - 4 - nitro -1 - (4 - bromophenyl) - 3 - methyl - 2 -pyrazolin - 5 - one in water and obtained the analogous 4-oxo compound. Acid hydrolysis of rubazonic acids, which are 4-imino-2-pyrazolin-5-ones, leads to 2-pyrazolin-4,5-diones.424 809 Oxidation of 4,4 -bis(2-pyrazolin-5-ones) or of rubazonic acids with nitric acid809 forms the 4,5-diones. 

It is known that 4-benzal-l-phenyl-A -pyrazolin-5-one reacts both like an heterodiene and an alkene in a Diels-Alder reaction towards 2,3-dimethylbutadiene <88T5229>. The 1,3-dipolar cycloaddition of nitrones to the N//-tautomer of l-phenyl-3-methyl-3-pyrazolin-5-one yields a nonisolated cycloadduct which rearranges to a 4-substituted derivative of the starting material (4-substituent = CH(Ar)— N(Ph)—OH) <94JCR(S)154>. 

Condensation of 140 with 3-methyl-l-phenyl-pyrazolin-5-(4//)-one was carried out on alumina support and under solvent-free conditions using MWI to give 3-methyl-4-[(chromon-3-yl)methylene]-l-phenyl-pyrazolin-5-(4//)-ones 142 in 59-87% yields within 2 min (Scheme 28). The same reaction in refluxing dioxane using a catalytic amount of triethylamine required 45 min to give lower yields (02SC497). 

Chiesa, C., Oefner, P. J., Zieske, L. R. and O Neill, R. A. Micellar electrokinetic chromatography of monosaccharides derivatized with l-phenyl-3-methyl-2-pyrazolin-5-one. J Capillary Electrvphor, 2,175, 1995. 

The stability of the pyrazolinone tautomers was related to their scale of aromaticity.Experimental values for the tautomerism of pyrazolinone derivatives were obtained by flash vacuum pyrolysis (FVP), which allowed the calculation of the effect of the temperature on the equilibrium between tautomers. The variation of Kj with the temperature was determined by H NMR in solution for the model compound l-phenyl-3-methyl-2-pyrazolin-5-one (Scheme 25), showing that at 0 K the only tautomers present are either the NH or the OH ones. Temperature and solvent effects on the prototropic equilibrium of the model compound in solution showed that... 

A comprehensive theoretical smdy of some pyrazolones has been presented. The predicted tautomeric equilibrium constants of these compounds were found to be in good agreement with existing experimental data, indicating that the oxo tautomers are present in aqueous solution whereas, in the main, the hydroxy tautomers predominate in the gas phase. It has been shown that, in solution, the most abundant tautomer of both l-(2, 4 -dinitrophenyl)-3-methyl-2-pyrazolin-5-one and its 1-phenyl derivative is dependent on the solvent used, while an NMR study of a number of l(2)//-dihydropyrazolo[3,4-fc]pyridin-6-ones has revealed that they all exist as 2//-tautomers both in solution and in the solid state. DFT and ab initio calculations have been carried out to investigate the stability of different tautomers of 2-hydroxy- and 2,3-dihydroxy-pyrazine in the gas phase and in different media. The data obtained indicated that 2-hydroxypyrazine is more stable than its 2-keto tautomer in the gas phase, whereas in solution the stability order is reversed. For 2,3-dihydroxypyrazine it appears that the intramolecular hydrogen-bonded hydroxyoxo and the a-diketo tautomers are the most stable species at all theoretical levels in the gas phase. Both spectroscopic and theoretical studies of the tautomerism of 2,1,3-benzothiadiazinone 2,2-dioxides and other related fused heterocyclic amides have predicted that the keto form (415) is the most abundant tautomer in the gas phase, whereas the NH hydroxy form (416) is the preferred tautomer in solution and in the solid state. 

Methyl-l -phenyl-2-pyrazolin-5 -one CDCI3 -186.4 -54.5 C- N and H- coupling constants 77JCS P2)1024 ... 

Scheme 19 contains all the reactions observed in different examples, none being so complex (B-76MI40402). Most studies deal with the methylation of 3-methyl-1-phenyl-pyrazolone, since in this case one of the products obtained is antipyrine (2,3-dimethyl-l-phenyl-3-pyrazolin-5-one), one of the classical antipyretic agents (Section 4.04.4.1.1). 

Finally, benzpiperylon or l-(l-methyl-4-piperidyl)-3-phenyl-4-benzyl-2- (or 3-) pyrazolin-5-one has been utilized by Sandoz as an investigational agent in connective tissue disorders (B-76MI40404). 

Methyl-l-phenyl-3-pyrazolin-5-one gives a green-black dye (736) with 4-nitroso- or 4-amino-dimethylaniline and silver chlorides in the presence of light, a process of great importance in colour photography (B-76MI40403). 

Pyrazolin-5-one, 3-methyl- H NMR, 5, 187 (B-73NMR165) 2-Pyrazolin-5-one, 3-methyl-1 -phenyl- H NMR, 5, 187 (B-73NMR165)... 

Benzylidene-3-methyl-l phenyl-2-pyrazolin-5-one on treatment with 2,4-dinitrophenylhydrazine and hydroxylamine hydrochloride afforded the pyrazolo[3,4-dpyrazole (96) and the isoxazolo[3,4-cl-pyrazole (97), respectively.101... 

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