L-Phenyl-3- pyrazoline

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). 

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). 

Dippii solution I Dissolve 1 g 4-aminoantipyrine (4-aminophenazone 4-ami-no-2,3-dimethyl-l-phenyl-3-pyrazolin-5-one) in 100 ml 80% ethanol. 

Dimethyl-l-phenyl-3-pyrazolin-5-one, a299 Dimethyl propanedioate, d630... 

Reisch J, Ekiz N, Gneri T. Fotoabbau von 4-isopropyl-2,3-dimethyl-l-phenyl-3-pyrazolin-5-on (propyphenazon) 49. Mittellung foto und strahlenchemische studien. Pharmazie 1986 41 287-288. 

Dimethylenemethane. See Allene under Allenic Compounds A133-R Dimethylketone, See Acetone A33-R Di (3 raethylpentynyl) 3"peroxide. See under Acetylene Hydroperoxides A(56-R 2,3-Dimethyl- l-phenyl-3-pyrazolin-5-one. 

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). 

The rearrangement of 4-dimethylamino-2,3-dimethyl-l-phenyl-3-pyrazolin-5-one to a 2-pyrazolin-5-one has already been mentioned (eq. 169). 4-Benzylideneamino-2,3-dimethyl-l-phenyl-3-pyrazolin-5-one reacts with dimethyl sulfate in aqueous media to give the 4-methyl-amino analog.940 Presumably the Schiff base is hydrolyzed and the resulting amino group is methylated. 4-Dimethylamino-3-pyrazolin-5-ones react with phosphorus oxychloride by conversion to the metho-chloride of a pyrazole.1000... 

There has been considerable interest in the preparation of 5-oxo-3-pyrazolin-4-carboxaldehydes (listed in Table XXXI) because of their close relationship to antipyrine (2,3-dimethyl-l-phenyl-3-pyrazolin-5-one). The most frequently used preparation of these compounds has already been mentioned (eq. 135, p. 54). This consists of treating the condensation products of 3-pyrazoIin-5-ones and chloral with base.107,196,889,893,896,901,1190 The McFadyen-Stevens aldehyde synthesis has been applied to the preparation of both 5-oxo-3-pyrazolin-3-carboxaldehydes698 and -4-carboxaldehydes.204,892,1634 This is illustrated in eq. 220. The final step is usually carried out in glycerol at... 

Bis(3-methyl-2-benzoyl-l-phenyl-3-pyrazolin-5-one) has been reported as the product obtained from treatment of 4,4 -bis(3-methyl-l-phenyl-2-pyrazolin-5-one) with benzoyl chloride.1056... 

Pyrazolin-5-ones form complexes with both inorganic and organic compounds much more readily than do the 2-pyrazolin-5-ones. The most extensive series of complexes is that formed with a variety of metallic salts. Antipyrine (2,3-dimethyl-l-phenyl-3-pyrazolin-5-one) forms a series of complexes with salts of divalent, trivalent and tetra-valent metals. Two molecules of antipyrine form a complex with one molecule of copper, cadmium, cobalt and zinc salts.266,866,1116 Complexes prepared from metallic nitrates are usually hydrated.1322 There also exists a series of complexes in which three molecules of antipyrine form a complex with one or two molecules of metallic salts. Such complexes form with two molecules of simple ferric salts272 or with one of complex iron cyanides.608 Nitrates of thorium, lanthanum, cerium and samarium also give such complexes.841 This ratio also occurs in some antipyrine complexes with cadmium and zinc thiocyanate.266 A number of salts of rare earths and iron which have complex anions such as thiosulfate, thiocyanate, dithionic acid and complex iron cyanides form complexes in which six molecules of antipyrine are present.405,408 608,841,950 Stannic chloride forms salts containing three or four molecules of antipyrine and hydrochloric acid.46... 

Verkade and Dhont1531 have treated 3,4-dimethyl-2-pyrazolin-5-one and 4-methyl-3-phenyl-2-pyrazolin-5-one with phenyldiazonium chloride, forming respectively 3,4-dimethyl-2-phenylazo-3-pyrazolin-5-one, m.p. 273°, and 4-methyl-3-phenyl-2-phenylazo-3-pyrazolin-5-one, m.p. 212°. 2,3-Dimethyl-l-phenyl-3-pyrazolin-5-one reacts with thio-oyanogen to give its thiocyanate salt and 2,3-dimethyl-l-phenyl-4-thiocyanato-3-pyrazolin-5-one, m.p. 125°.742... 

Dimethyl-l-phenyl-5-oxo-3-pyrazolin-4-carboxaldehyde reacts with 2,3-dimethyl-l-phenyl-3-pyrazolin-5-one to give tris(2,3-dimethyl-I-phenyl-5-oxo-3-pyrazolin-4-yl)methane.107 Mannich and Krosche946 have treated 2,3-dimethyl-l-aryl-2-pyrazolin-5-ones with hexamethylenetetramine to give compounds of the type shown in eq. 241. The aryl groups were phenyl and p-tolyl. The reaction of 2,3-... 

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