Showing papers on "Pyrazoline published in 1969"

Synthesis of Adamantane Derivatives. III. Synthesis of Adamantane Heterocycles

Abstract: Preparation of 1-adamantyl and adamantane-1-carbonyl derivatives having benzimidazole, 1,3,5-oxadiazole, oxazoline-2, quinoxaline, 2-aminothiazole, thiazolone, 2-methylthiazole, 1,2,3-thiadiazole, pyrazole or pyrazoline ring is described.

Preparation, absolute configuration, and thermolysis of (3R:5R)-(+)-trans-3,5-dimethyl-1-pyrazoline

Abstract: Thermolysis of (3R:5R)-(+)-trans-3,5-dimethyl-1-pyrazoline produces 25.6% of trans-1,2-dimethyl-cyclopropane of 23% optical purity having the S:S configuration. Thermolysis mechanisms which explain the racemization and the double inversion process are discussed. The absolute configuration of active-2,4-pentanediol and 2,4-dibromopentane is correlated with that of 4-hydroxy-1-pentene.

Electron-impact induced fragmentation of substituted pyrazolone azomethine dyes

Abstract: The mass spectra of 18 substituted 1-(p-R2-phyeyl)-3-R3-4-(p-R1-phenylimino)-2-pyrazolin-5-ones have been obtained. The major cleavages under electron bombardment take place in the pyrazoline nucleus, producing four major fragment ions whose abundance is related primarily to the electronic properties of R1. These ions appear to be produced from the molecular ion via an intermediate formed by the loss of CO. In most instances metastable ions are observed for the overall decomposition of the molecular ion to the four major fragment ions. A mechanism is proposed for these cleavages.

E.S.R. of nitroxide radicals. II. Photosensitization of indoles, phenols, and thiols by a diphenylpyrazoline

Abstract: Indoles, phenols, and thiols have been shown to undergo photosensitization by a diphenylpyrazoline in non-polar solvents. The intermediate radicals produced have been trapped using a nitrosoalkane scavenger, and the resulting nitroxide radicals examined in situ by e.s.r. Fluorescence studies of these systems have shown that indoles and phenols strongly quench the singlet excited state of the diphenyl- pyrazoline, whereas thiols have no effect.

Spectral-luminescent properties of some optical bleaches of the pyrazoline series

Abstract: The bleaching effect accomplished by OB consists of an increase in the blueness and brightness of the treated mater ia l due to the intense blue f luorescence of these compounds. The concept of the degree of whiteness (W), which charac te r i zes the position of the test sample relat ive to an ideally white sample in the standard co lor imet r ie space, is used to descr ibe the bleaching effect in co lor imet ry . The empir ical r e l a tionship which gives the quantitative expression for the degree of whiteness takes both of these effects into account and has the fo rm [1]

Studies of Acenaphthene Derivatives. XVII. The Reaction of Benzylideneacenaphthenone with Hydrazines

Abstract: The reactions of benzylideneacenaphthenones with hydrazines are reported. The reaction of benzylideneacenaphthenone with hydrazine hydrate in methanol at 40°C gave 1-hydroxy-2-hydrazinobenzylacenaphthylene, which was then cyclized to the 1-acetylpyrazoline by treating it with acetic anhydride. The hydrazino compound reacted with phenyl isocyanate to give the 1:2-adduct, which, when then treated with hydrochloric acid, suffered ring closure to the pyrazoline compound. Under severe conditions with hydrazine hydrate, however, the reductive cleavage reaction took place, giving the hydrazones of both acenaphthenone and benzaldehyde. Similar phenomena were also observed in the reaction with p-substituted benzylideneacenaphthenones. On the other hand, the reaction with phenylhydrazines in ethanol containing sulfuric acid afforded directly the expected pyrazolines, from which pyrazoles were then prepared by treating them with lead tetraacetate. Furthermore, the corresponding pyridazine was formed in the reaction ...