Etude en Résonance Magnétique Nucléaire du Carbone‐13 de N‐Aryl Pyrazolines‐2 Diversement Substituées. Effets de Substituant et Etude Conformationnelle

Abstract

The -C chemical shifts of 1-phenyl-2-pyrazoline and 25 N-nitropheny1-2-pyrazolines, with different substituents on the heterocyclic ring, have been assigned. These values are discussed as a function of the steric and electronic nature of the various substituents. The steric effects produced conformational modifications, both in the nitrophenyl and 2-pyrazoline moieties, which explain some of the chemical shifts.Les dkplacements chimiques du carbone-13 de la phknyl-1 pyrazoline-2 et de vingt-cinq N-nitrophhyl pyrazolines-2, diversement substitukes sur I'hCtCrocycle, ont Ctk complktement attribuks. Ces valeurs sont discutkes en fonction des contraintes klectroniques et stkriques des diffkrents substituants. Les effets stkriques entrainent des modifications de la conformation aussi bien du groupement nitrophknyle, que du cycle pyrazoline-2, ce qui explique les variations de certains dkplacements chimiques. AITRIBUTION DES DEPLACEMENTS CHIMIQUESA partir de critbres classiques, telle que I'analyse des spectres partiellement dCcouplCs, et en utilisant certaines donnkes de la littkrature, en particulier les effets de substituants en skrie benzknique,6 nous avons pu attribuer I'ensemble des dkplacements chimiques du composC l a et des dCrivks de la sCrie 2 .

X-ray Molecular Structures of 23 N1-4-Nitrophenyl, 2,4-Dinitrophenyl, and 2,4,6-Trinitrophenyl-2-pyrazolines

“…5-methyl-1-(2,4,6-trinitrophenyl)-4,5-dihydro-1 H -pyrazole ( 3c , mp: 179–180 °C), 3,5-dimethyl-1-(2,4,6-trinitrophenyl)-4,5-dihydro-1-pyrazole ( 3d , mp: 174–176 °C), 3-isopropyl-4,4-dimethyl-1-(2,4,6-trinitrophenyl)-4,5-dihydro-1 H -pyrazole ( 3h , mp: 201–202 °C), 3- tert -butyl-1-(2,4,6-trinitrophenyl)-4,5-dihydro-1 H -pyrazole ( 3i , mp: 144–145 °C), 3-bromo-1-(2,4,6-trinitrophenyl)-4,5-dihydro-1 H -pyrazole ( 3o , mp: 176–177 °C), , and 3-bromo-5-methyl-1-(2,4,6-trinitrophenyl)-4,5-dihydro-1 H -pyrazole ( 3q , mp: 186–187 °C). , …”

“…At the beginning, our own research , consisted of extending the reaction discovered by Mousseron et al to other pyrazolines and other halonitrobenzenes. Subsequently, when 1 H, 13 C, 15 N NMR was available, a series of papers were devoted to the use of these techniques to structural studies of nitrophenylpyrazolines. − A less explored approach to the structure of 1-nitrophenyl-2-pyrazolines was the use of mass spectrometry to determine the gas-phase basicities of these compounds, whose p K a values we have previously determined. − …”

The use of DOSY experiments to determine the solution structures of coinage metal pyrazolates: The case of {[3,5‐(CF3)2Pz]Ag}3

“…Compound (12Ag) 3 was prepared according to reference Dias et al [ 34 ] Antipyrine 1 is a commercial compound. 1‐(2,4‐dinitrophenyl)‐3,5‐dimethyl‐4,5‐dihydro‐1 H ‐pyrazole 2 and tris(2‐methyl‐1 H ‐benzimidazolyl) methane were reported in references, [ 51,52 ] respectively. Compound 4 was synthesized by Ana San‐Félix's research group according to reference San‐Félix et al53 The origin of the compounds of Figure 4, except 5 and 6 that are commercial, were prepared for this work according to literature procedures: 7, 54 8 55 and 9.…”

Basicity of 1-nitroaryl-4,5-dihydropyrazoles: pKa �measurements and theoretical calculations

“…The synthesis of and spectroscopic data for all the 4,5-dihydropyrazoles used in this study (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21) can be found in the literature. [12][13][14][15][16][17] Basicity measurements. The pK a values of the 16 dihydropyrazoles 5, 8-17, 6 and 18-21 in water at 20°C are reported in Table 1.…”