Nuclear magnetic resonance nitrogen-15 spectra

Since the product slowly darkens on exposure to air, it should be stored under nitrogen in a refrigerator. The compound solidifies on cooling m.p. 16.0-16.5°. Nuclear magnetic resonance spectrum (neat, tetramethylsilane internal standard) singlets at d 7.00 (aromatic protons), 3.93 (CH2), and 2.24 p.p.m. (NH). 

Primary amines may be readily distinguished from secondary and tertiary analogues by the presence of two absorption bands in the infrared spectrum between 3320 and 3500 cm-1 (symmetric and antisymmetric NH str.). Secondary amines exhibit a single absorption band at about 3350 cm-1 (NH str.). In both cases deformation modes for the NH bond appear at about 1600 cm-1. There is no satisfactory absorption to allow a definitive characterisation in the case of tertiary amines. In the nuclear magnetic resonance spectrum of primary and secondary amines, the nitrogen-bound hydrogens are recognisable by their replaceability on the addition of deuterium oxide. 

The nuclear magnetic resonance spectrum of pseudouridine is in agreement with this formulation, in that it shows that there is no proton attached to C-5 in the pyrimidine ring. Moreover, the signal from the C-1 proton occurs at a S value lower than that given by the C-1 proton in uridine, as would be expected for a C—CH proton as against an N—CH proton. The ultraviolet spectrum shows that neither nitrogen atom is substituted, and methylation with diazomethane yields two mono-A -methyl derivatives and one di-iV-methyl derivative. 

Lerner L, Bax A (1986) Sensitivity-enhanced two-dimensional heteronuclear relayed coherence transfer NMR spectroscopy. J Magn Reson 69 375-380 Leupin W, Wagner G, Denny WA, Wiithrich K (1987) Assignment of the carbon-13 nuclear magnetic resonance spectrum of a short DNA-duplex with proton-detected two-dimensional heteronuclear correlation spectroscopy. Nucl Acid Res 15 267-275 Levy GC, Lichter RL (1979) Nitrogen-15 nuclear magnetic resonance spectroscopy. John Wiley, New York... 

What would be the nuclear magnetic resonance spectrum for a proton resonance line that was split by interaction with (a) two and (b) three equivalent nitrogen nuclei (the spin of a nitrogen nucleus is 1) ... 

Physical Chemical Characterization. Thiamine its derivatives, and its degradation products have been fuUy characterized by spectroscopic methods (9,10). The ultraviolet spectrum of thiamine shows pH-dependent maxima (11). H, and nuclear magnetic resonance spectra show protonation occurs at the 1-nitrogen, and not the 4-amino position (12—14). The H spectmm in D2O shows no resonance for the thiazole 2-hydrogen, as this is acidic and readily exchanged via formation of the thiazole jlid (13) an important intermediate in the biochemical functions of thiamine. Recent work has revised the pTC values for the two ionization reactions to 4.8 and 18 respectively (9,10,15). The mass spectmm of thiamine hydrochloride shows no molecular ion under standard electron impact ionization conditions, but fast atom bombardment and chemical ionization allow observation of both an intense peak for the parent cation and its major fragmentation ion, the pyrimidinylmetbyl cation (16). 

Then, with the help of a colleague, Asher Mandelbaum, at the Technion in Haifa, we got a high-resolution mass spectrum, which indicated that the molecule contains a nitrogen, certainly not a common feature in fatty acids. However, the structure was now close at hand. Some more mass spectra and a better nuclear magnetic resonance (NMR) led to a final formulation of the ligand as arachidonoyl ethanol amide (Devane, Hanus, et al., 1992). 

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