Nuclear magnetic resonance spectroscopy esters

Tracey, A.S. and M J. Gresser. 1988. The characterization of primary, secondary, and tertiary vanadate alkyl esters by 51-V nuclear magnetic resonance spectroscopy. Can. J. Chem. 66 2570-2574. 

Lim, S., and Seib, P. A. 1993. Location of phosphate esters in wheat starch phosphate by 31P-nuclear magnetic resonance spectroscopy. Cereal Chem. 70, 145. 

Nuclear magnetic resonance spectroscopy can be used to distinguish between the phosphate esters of steroids. The free steroids can be distinguished by infra-red spectrophotometry, but the phosphate esters are sufficiently polar to give rise to absorption bands that dominate the IR spectra and make distinction difficult. The NMR spectra of these steroid esters are not subject to this interference, and although they may be very difficult to interpret, they do provide the necessary distinction. 

Supercritical fluid chromatography was coupled online to Proton High Field Nuclear Magnetic Resonance Spectroscopy by an specially designed pressure-proof continuous-flow probe head. Separation of phthalate esters was carried out under supercritical conditions using carbon dioxide as eluent. ... 

Nuclear magnetic resonance spectroscopy may provide a convenient measure of the formaldehyde or formic acid produced in some periodate oxidations, and may also permit differentiation between free formic acid and that bound as formic esters deuterium oxide is a convenient solvent for these determinations. Mechanical, automated techniques for determining the amounts of various oxidation products have been developed. ... 

These studies opened the way to a new area of macromolecular science based on renewable resources pursued by approaches based on pristine oils and their commercial derivatives. The bulk reaction of epoxidised vegetable oils with an excess of furfurylamine was studied in green chemistry conditions and formd to take place through two parallel mechanisms occurring at approximately the same rate. That is, aminolysis of ester bonds and oxirane ring-opening, as shown in Scheme 7.5 for the case of epoxidised linseed oil [12], These reactions were followed by Fourier-Transform infrared spectroscopy and H-nuclear magnetic resonance spectroscopy, respectively, and both reached completion. 

With the advent of high resolution proton and carbon nuclear magnetic resonance spectroscopy, however, determining the DS and the DS distribution of mixed ester systems by aqueous saponification has become obsolete. Numerous studies have shown NMR to be a fundamental tool for probing the microscopic behavior of a... 

The role of specific interactions in the plasticization of PVC between the carbonyl fimctionality of the plasticizer were proposed on the basis of results from Fourier transform infrared spectroscopy. Reported shifts in the absorption frequency of the carbonyl group of the plasticizer ester to lower wave number are indicative of a reduction in polarity. These ideas have been extended using newer analytical techniques, in particular molecular modeling and solid-state nuclear magnetic resonance spectroscopy (nmr). 

A potassium bromide pellet prepared from the major component indicated the formation of an ester linkage, the presence of a phosphate, and an A -t-butoxycarbonyl group. A UV spectrum with a maximum absorption at 257.5 nm identical to that of ATP eliminated the possibility that aminoacylation may have taken place at 6-amino group of nucleotide. Nuclear magnetic resonance spectroscopy demonstrated the presence of tertiary butyl protons. On the basis of the above evidence, structure (II) has been assigned to this product. 

The structures of vanicosides A (1) and B (2) and hydropiperoside (3) were established primarily by one- and two-dimensional nuclear magnetic resonance (NMR) spectroscopy techniques and fast atom bombardment (FAB) mass spectrometry (MS).22 The presence of two different types of phenylpropanoid esters in 1 and 2 was established first through the proton (4H) NMR spectra which showed resonances for two different aromatic substitution patterns in the spectrum of each compound. Integration of the aromatic region defined these as three symmetrically substituted phenyl rings, due to three p-coumaryl moieties, and one 1,3,4-trisubstituted phenyl ring, due to a feruloyl ester. The presence of a sucrose backbone was established by two series of coupled protons between 3.2 and 5.7 ppm in the HNMR spectra, particularly the characteristic C-l (anomeric) and C-3 proton doublets... 

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