Pyridine nuclear magnetic resonance spectroscopy

Infrared spectroscopy is an important technique for studying acidity. Acidic OH groups can be studied directly. Probe molecules such as pyridine may be used to study both Bronsted and Lewis acidity since two forms of adsorbed probes are easily distinguished by their infrared spectra. Quantitative infrared spectroscopy may be performed by measuring the spectrum of acidic OH or probes adsorbed on thin, self-supporting wafers of the acidic solid. Other spectroscopic methods which may provide information in specific cases include Fourier Transform Raman spectroscopy, electron spin resonance spectroscopy, ultraviolet spectroscopy, and nuclear magnetic resonance spectroscopy. 

Nuclear Magnetic Resonance Spectroscopy.—As noted above, conformational analysis of bicyclo[3.3.1]nonanes is still a topic of considerable interest. A variable-temperature n.m.r. analysis now provides the first case in which the boat-chair-chair-boat equilibrium is directly observed in the amines (17) and (18). In a related case, re-examination of the acetal (19) suggests that the preferred conformation involves a chair carbocyclic ring and a boat heterocyclic ring. This conclusion was made by n.m.r. analysis, using lanthanide shift reagents, by a study of nuclear Overhauser effects, and by measurement of relaxation times of protons. Details have been reported for other 3-azabicyclo[3.3.1]nonanes, and the non-additivity of substituent effects on chemical shifts in 9-thiabicyclo[3.3.1]non-2-enes has been analysed. Both and n.m.r. data have been reported for a series of 9-borabicyclo[3.3.1]non-anes and their pyridine complexes. 

Sarma RH, Mynott RJ (1973) Confoimatirai of pyridine nucleotides studied by phosphorus-31 and hydrogen-1 FoniiCT transform nuclear magnetic resonance spectroscopy. I. Oxidized and reduced monrmucleotides. J Am Chem Soc 95 1641—1649... 

Extensive nuclear magnetic resonance and ultraviolet spectroscopy methods were reviewed in <1996CHEC-II(7)363>, as well as mass spectral fragmentation patterns of [l,2,3]triazolo[4,5-/ ]pyridines (Section 7.10.8.1). More recently, furoxan rearrangement of some pyridofuroxan derivatives has been studied by H, and... 

Equivalent Weight. Three reliable analytical methods are available to determine the equivalent weight of CTPB prepolymer (1) titration by 0.1 N sodium methylate in pyridine solution to the thymol blue end point, (2) infrared spectroscopy, and (3) nuclear magnetic resonance. Satisfactory agreement has been obtained between these instrumental analyses and the acid content as determined by titration (Table XVI). 

To benzo[A]quinolinyl palladium(II) pyridine-sulfonamido complex (12.8 mg, 0.0200 mmol) in acetonitrile-c/i (0.6 mL) at 23 °C was added l-chloromethyl-4-fluoro-l,4-diazoniabicyclo [2.2.2]octane bis(tetrafluoroborate) (7.1 mg, 0.020 mmol). After stirring for 10 min at 23 °C, the colorless suspension formed a dark purple solution. The complex was characterized by nuclear magnetic resonance (NMR spectroscopy) in acetonitrile solution without purification. ... 

---