5-Phenyl-3-pyrazoline

In 1912 Kishner and Zavadovskii reported the synthesis of phenylcyclopropane by heating decomposition of 5-phenyl-3-pyrazoline. The Kishner cyclopropane synthesis has become wellknown due to its unique and the smallest cyclic core structure. ... 

A mixture of 118 g 5-phenyl-3-pyrazoline 46, prepared by procedure 30 g pulverized potassium hydroxide and 2.5 g asbestos was heated in a 1 L, three-necked flask equipped with a stirrer and a Claisen distillation head. The temperature was raised slowly and the heat was shut off at the first sign of reaction. When the exothermic reaction ceased the temperature was again raised and the product was distilled. Both the distillate and the residue were steam distilled and the steam distillate was taken up in ether and dried first with sodium sulfate and then with sodium and redistilled. The product 47 was collected at 60-63 C (11 mm Hg) and was finally... 

ALKANOLAMNES - ALKANOLAMINES FROM OLEFIN OXIDES AND AL ONIA] pol 2) l-Phenyl-3-[p-(diethylamino)styryl]-5-[p-(diethylamino)phenyl] pyrazoline [57609-72-0]... 

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). 

Aroylhydrazines are readily oxidised in protic solvents. Benzoylhydrazine and 2-benzoylphenylhydrazine show anodic waves in an acetate buffer at +0.08 and +0.02 V vs. see respectively [147], The most studied member of this group, because of its importance as the photographic developer phenidone, is 1-phenyl-pyrazolin-3-one 33. Phenidone shows a one-electron oxidation wave at a rotating... 

However, in that survey Schein and Tyutnev question the intermolecular origin of cr. They compared cr values derived from studies of hole transport in 1-phenyl-3-((diethylamino)styryl)-5-(p-(diethylamino)phenyl)pyrazoline (DEASP) molecules, derivatives of pyrazoline, whose dipole moment is 4.34 D, blended with either polystyrene or polycarbonate as function of concentration. They found that cr is independent of the matrix material and that a remains constant when the concentration of DEASP increases from 10% to 70% while one would expect that cr increases as... 

In the course of an extensive study of the chemistry of azo compounds, Overberger et al. [47a] prepared 1-pyrazolines, which may be considered cyclic azo compounds, by the addition of diazoalkanes to styrene. The reaction is considered a stereospecific 1,3-dipolar addition and, in the reaction between />-methoxyphenyldiazomethane and />-methoxystyrene both trans-3,5-bis-(p-methoxyphenyl)pyrazoline (m.p. 129°C, dec.) and c/s-3,5-bis(/>-methoxy-phenyl)pyrazoline were prepared and separated [47b]. 

The features of the electronic structure of aryl-substituted pyrazolines influence their chemical properties. For example, in the case of 3-substituted 7V-phenyl-pyrazolines 100 reactions of formylation, acylation, nitration, sulfonation, azocoupling and other electrophilic processes involve the para position of the 7V-phenyl ring, with formation of compounds 101 [103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113]. On the other hand, some electrophilic reactions, including nitration, bromination, chlorination, formylation and azocoupling, for 3-unsubstituted pyrazolines 102 occur at position 3, yielding heterocycles 103 and in some cases as a mixture with 104 [108, 114, 115] (Scheme 2.26). This fact provides evidence for orbital control of these reactions. 

Thoms and Schnupp741 reduced pyrazole itself to pyrazoline, with a palladium catalyst in acetic acid at 20° but this is the only reported catalytic reduction of a pyrazole ring unsubstituted on nitrogen. Under these conditions V-phenyl pyrazoles are converted to V-phenyl-pyrazolines and then at 80° to N-phenylpyrazolidines.741... 

In a similar reaction benzylideneacetophenone affords 3-benzoyl-4-phenyl-pyrazoline, also almost quantitatively.17 A large number of pyrazoline derivatives can be obtained in similar reactions of diazomethane or diazoacetic ester. 

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). 

Multilayer devices use PBD and tris-(8-hydroxyquinoline)-alumin-um (Alqs) with l-benzothiazol-3-phenyl-pyrazoline as blue dye, which has an emission peak at 445 nm. Alqs enhanees the electron injection and luminous efficiency. ... 

Benzoate 2-naphthoate ethylene, 357 Benzoic acid, 393, 396, 398 Benzonitrile, 263, 286, 318 Benzophenone, 223, 312 3,3, 4,4 -Benzophenone dianhydride, 477, 481 3,3, 4,4 -Benzophenone tetracarboxylic dianhydride, 494 1 -B enzothiazol-3 -phenyl-pyrazoline, 32 Benzotriazole, 317... 

Metnyl.5.phenyl-/) -pyrazolin-oarbon> s4uie-(l ).metbyle8ter 23 II169. 

A soln. of 3-diazoacetyl-3-methyl-4-phenyl- -pyrazoline in methanol treated with 5%-KOH soln., and allowed to stand overnight at room temp. Js. isomer (startg. m. f. 547). Y 76%. J. A. Moore and R. W. Medeiros, Am. Soc. 81,6026 (1959). 

Aldehydes and ketones react with azolinones. The reaction between aldehydes and 2-phenyl-5-oxazolinone (131 Y = H), formed in situ from PhC0NHCH2C02H and AC2O, gives azlactones (131 Y = RCH). Similar reactions are given by 4-thiazolidinones, e.g. (132) gives (133) (79AHC(25)83), and 4-imidazolinones. In pyrazolin-5-ones the 4-position is sufficiently activated for condensation to occur with ketones in acidic media (Scheme 8) (66AH06)347). 

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

Acyl-, 4-alkoxycarbonyl- and 4-phenylazo-pyrazolin-5-ones present the possibility of a fourth tautomer with an exocyclic double bond and a chelated structure. The molecular structure of (138) has been determined by X-ray crystallography (Table 5). It was shown that the hydroxy group participates in an intramolecular hydrogen bond with the carbonyl oxygen atom of the ethoxycarbonyl group at position 4 (8OCSCII21). On the other hand, the fourth isomer is the most stable in 4-phenylazopyrazolones (139), a chelated phenyl-hydrazone structure. 

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). 

A mechanism has been proposed to rationalize the results shown in Figure 23. The relative proportion of the A -pyrazolines obtained by the reduction of pyrazolium salts depends on steric and electronic effects. When all the substituents are alkyl groups, the hydride ion attacks the less hindered carbon atom for example when = Bu only C-5 is attacked. The smaller deuterohydride ion is less sensitive to steric effects and consequently the reaction is less selective (73BSF288). Phenyl substituents, both on the nitrogen atom and on the carbon atoms, direct the hydride attack selectively to one carbon atom and the isolated A -pyrazoline has the C—C double bond conjugated with the phenyl (328 R or R = Ph). Open-chain compounds are always formed during the reduction of pyrazolium salts, becoming predominant in the reduction of amino substituted pyrazoliums. 

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). 

Phenidone, l-phenyl-3-pyrazolidone (738) (B-76M140404), has been used as a nonstaining, high contrast photographic developer. New optical brighteners containing 2-pyrazolines (739) and pyrazoles (740) have been synthesized recently and their properties and applications reviewed (75AG(E)66s). 

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