Eine qualitative Probe auf Monosaccharide

Ohne Zusammenfassung     

Étude de quelques dérivés de la pyrazoline-2: Spectres infrarouge et methode CNDO/2

The infrared spectra of some derivatives of 2-pyrazoline have been studied in the region of the CN and N-H stretching bands.The N-H stretching frequency seems to be related to Taft's σ^* constants of the substituents bound to the intracyclic carbon atoms. The “acidity” of this group seems to be considerably less than in pyrrole or in carboxylic amides.Absorption spectra of the pure compounds or of moderately concentrated solutions suggest the existence of intermolecular hydrogen bonding.The hybridization state of nitrogen atom (1) seems to be approximatively sp³, without any noticeable conjugation with the CN(2) double bond. In those cases where two conformers could be assumed to exist only one has been observed.These results are in accordance with those of a molecular orbital calculation by the CNDO/2 method. This calculation suggests that in 5-methyl-2-pyrazoline, the hydrogen atom bound to N(1) is trans with respect to the methyl group.     

π+-Electroproduction of hydrogen near threshold at four-momentum transfers of 0.2, 0.4 and 0.6 GeV2

The reaction e + p → e′ + π⁺ + n was measured near the one pion threshold, detecting the final electron and neutron in coincidence for values of q² = 0.2, 0.4 and 0.6 GeV². The normalized axial vector form factor to the nucleon $\text{F}{}_{\mathrm{<mtext>A</mtext>}}\text{(q}{}^2\text{)}\text{F}{}_{\mathrm{<mtext>A</mtext>}}\text{(0)}$ was determined from the data within a theoretical framework based on PCAC and current algebra.     

Spectroscopic studies on N,N-dimethylamides—III Amide-rotational barriers of N,N-dimethylbenzamides and -cinnamamides. A comparison of the NMR intensity ratio- and iterative total line shape method

Amide-rotational barriers of a series of para-substituted N,N-dimethylbenzamides and -cinnamamides have been obtained by both the intensity ratio method, according to Rogers and Woodbrey,² and an iterative total line shape analysis. From a comparison of the results, it is concluded that a discussion of rotational barriers obtained with the intensity ratio method should preferably be based on ΔG values, which are nearly equal for both methods, rather than on ΔG^? at other temperatures.     

Über 1, 5-Diphenyl-2, 3, 6, 7-tetrahydro-1H, 5H-pyrazolo[1, 2-a]pyrazole(2, 6-Diphenyl-1, 5-diazabicyclo[3, 3, 0]octane)

The synthesis of a 1, 5-diphenyl perhydro-pyrazolo-[1, 2-a] pyrazole (IV) (m. p. = 170–171°) by LiAlH₄-reduction of its 3, 7-dioxo derivative Va, one of the stereoisomers of V, is described. Va was obtained in small yield by the reaction of cinnamic acid with its hydrazide or with hydrazine. It proved to be identical with the compound obtained previously by interaction of cinnamic acid hydrazide with iodine which in the literature erroneously had been described as N, N′-dicinnamoyl hydrazine. This hydrazine now was obtained by bis-acylation of hydrazine with cinnamoyl chloride. In Va the extremely low NMR. absorption of the tertiary protons at ρ = 4,6 ppm is probably due to the spatial grouping with the proton situated in the deshielding region of the carbonyl group. Previously, another tertiary proton with a very low NMR. absorption at ρ = 4,85 ppm has been observed in the «bisimide M», the main criss-cross addition product of one mole benzaldazine and two moles of N-(n-butyl)-maleinimide. A stereostructure for bisimide M is now proposed, which is a hybrid between those of the bisimides L and H.     

Spectroscopic studies on N,N-dimethylamides—I: Structure-reactivity correlation for rotational barriers from a nuclear magnetic resonance study of p- and m-substituted N,N-dimethylbenzamides

Rotational barriers in 21 p- and m-substituted N,N-dimethylbenzamides in CDCl₃ as solvent have been determined using the intensity ratio method of Woodbrey. These data compare very well with values from the literature¹ obtained with a total line shape analysis. From structure-reactivity correlations evidence has been obtained for a relatively strong resonance interaction between the substituent in the aromatic ring and the partially double amide bond.