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. 

Acid YeUow 23 (31), commonly known as Tartraziae, stiU maintains sales of nearly 0.5 million /yr ia the United States. It was first discovered ia 1884 and is made by coupling equimolar quantities of diazotized sulfarulic acid to 3-carboxy-l- -sulfophenyl)-5-pyrazolone. Other monoazopyrazolone dyes of commercial importance iaclude Acid YeUow 17 (32) (sulfarulic acid — l-(2,5-dichloro-4-sulfophenyl)-3-methyl-5-pyrazolone and Acid YeUow 40 [6372-96-9] (33) (Cl 18950) (p-aminophenol l-(4-chloro-2-sulfophenyl)-3-methyl-5-pyrazolone) foUowed by esterification of the phenoUc hydroxy group with -toluenesulfonyl chloride. 

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). 

There is a large number of heteroaromatic coupling components of very different structural types. l-Aryl-3-methyl-5-pyrazolones have been widely used for yellow and orange monoazo dyes since the end of the 19th century. Other types have become important as a source of new industrially produced dyes in the last two decades. In reviews on industrial aspects (e.g., Schwander, 1982) these coupling components are classified not on the basis of their structures, but from the viewpoint of what is important for tinctorial properties of the dyes obtained with these types of coupling components. Here we will use a structural approach to systematization. 

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. 

The reaction of 3-methyl-5-pyrazolone with diethyl 2-acylmalonates at 140-150°C for 2 hr afforded pyrazolo[5,l-ft]oxazine-6-carboxylates (1665) in 22-64% yields [77JAP(K)77089],... 

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. 

Phenazone. Equimolar amounts of phenylhydrazine and ethyl acetoacetate are heated for 8 hours at 125°. The resulting phenyl-3-methyl-5-pyrazolone is dissolved in anisole and heated to 135°. Methyl bromide is passed through (bubbled into) the solution for 10 hours at 135°, and the anisole is removed by steam distillation. Phenazone is extracted from the remaining residue with chloroform and the chloroform is distilled or evaporated off The residue is recrystallized from ether. Mp 111-113°. Dosage 300 to 600 mg. This drug also has antipyretic action (reduces fever) and can cause rashes, nausea, and fainting. 

Phenyl-3-methyl-5-pyrazolone, 998 p-Phenylpl lenacy 1 bromide, 962 p-Phenylphenacyl esters, 363 Phenylpropiolic acid, 755, 776 Phenylpropionaldehyde, 906, 907 Phenyl propionate, 676... 

The discovery of insecticidal carbamates arose independently from studies on the naturally occurring toxin physostigmine (86), and from research on insect repellants. The latter produced some pyrazoles of which isolan was an example (87) (68MI10701), derived from 3-methyl-5-pyrazolone which is made by condensation of hydrazine with ethyl acetoacetate. 

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. 

First, 1 2 metal complexes of (mainly mono-) azo dyes, without sulfonic or carboxylic acid groups, and trivalent metals (see Section 3.11). The metals are preferably chromium and cobalt nickel, manganese, iron, or aluminum are of lesser importance. Diazo components are mainly chloro- and nitroaminophenols or amino-phenol sulfonamides coupling components are (3-naphthol, resorcinol, and 1-phe-nyl-3-methyl-5-pyrazolone. Formation of a complex from an azo dye and a metal salt generally takes place in the presence of organic solvents, such as alcohols, pyridine, or formamide. An example is C.I. Solvent Red 8, 12715 [33270-70-1] (1). 

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. 

Compound 9 is prepared by 1 2 chromation in organic medium [12] Diazo-tized l-amino-2-hydroxy-4-nitrobenzene is coupled with 1-phenyl-3-methyl-5-pyrazolone. The resulting azo dye is heated at 110 °C in a mixture of formamide and a aqueous solution of chromium(m) formate. After completion of chromation, the dye 9 [64560-69-6] is precipitated with water. 

In the stepwise synthesis of the unsymmetrical complex dye 13 [ 70236-60-1] [10], the azo dye made from diazotized l-amino-2-hydroxy-5-nitrobenzene and 1-phenyl-3-methyl-5-pyrazolone and the 1 1 chromium complex obtained from 6-nitro-l-diazo-2-hydroxynaphthalene-4-sulfonic acid and 2-naphthol are heated together at 80 °C for 5 h. The adduct is salted out with NaCl. A black powder is obtained that dyes wool and leather in dark brown shades. The resulting colors are fast, particularly on shrink-resistant wool. 

Methyl-5-pyrazolone 52 (Scheme 14) is allylated at C-4 under Pd(0) catalysis, as exemplified by its transformation into 53. Only when two allylic... 

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 ... 

Sulfon acid blue R, 218 Sulforation general, 6, 82 vessels, 101, 105 Sulfone reagent, 185, 211, 243 Sulfones, 85 Sulfonic adds rearrangement, 82 separation, 31 l-p-Sulfophenyl-3-methyl-5-pyrazolone, 129 Sulfoxylate, 80 Sulfur black T, 102, 337 Sulfur fusions, 332 Sulfuric add, heat capadty, 70 Sulfuryl chloride, 67, 145 Sun yellow G, 296 Superheater, 142... 

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. 

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