Nuclear magnetic resonance spectroscopy carboxylic acids

The trifluoroethyl (CF3CH2—) derivative of organic acids and alcohols has been found to be useful for distinguishing carboxyl from primary hydroxyl from secondary hydroxyl functional groups by F nuclear magnetic resonance spectroscopy (Roller and Dorn, 1982). This derivative is formed under conditions shown in reaction (4) ... 

Boni, R., DiBlasi, R., and Verdini, A. S. (1975). Macromolecules 8, 140. Conformational Properties of Poly (b-Azetidine-2-Carboxylic Acid) in Solution as Studied by Carbon-13 and Proton Nuclear Magnetic Resonance Spectroscopy. 

In order to co clarify the role of complex formation, the new data on stability constants should be accumulated, being collected at strictly similar conditions. It should be also mentioned that any analysis of equilibrium in solutions involving anions of polybasic hydroxy carboxylic acids requires the data on the deprotonation constants of the acid in question. This information would be crucial for conclusions regarding the presence and stability of mixed complexes in the system. Valuable knowledge about the structure of complex compounds present in solutions (and in precursors as well, see later) may be gained by means of vibrational spectroscopy (IR and Raman spectra) and nuclear magnetic resonance. 

Fulvic and humic acids have been investigated with carbon-13 and proton nuclear magnetic resonance spectrometry, GC/MS, and IR spectroscopy. The fulvic and humic acids were found to be predominantly carboxylic and aromatic with a high proportion of 0- and Ji-substituted carbon atoms, although aliphatic ones were also observed. 

The incorporation of an aspartic acid residue with a atom at the side-chain carboxyl function at position 25 into aspartyl protease has made this catalytically essential group visible for nuclear magnetic resonance (NMR) spectroscopy (Fig. 2)... 

Increasing lA concentration in copol5mierization results in lower viscosities (Fig. 1.14). lA content of copol5miers was determined using Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) and nuclear magnetic resonance (NMR) spectroscopies. The absoption bands at 1628 and 1730 cm due to C=0 stretching vibrations in carboxylic acid showed an increase... 

So far it has been assumed, without any proof, that sulfonic groups in SPPO are attached to aromatic rings. In principle, sulfonic groups could also be attached to methyl groups as in case of other modified PPO polymers, for example, carboxylated PPO or methyl ester carboxylated PPO [22]. Acid-base and conductimetric titrations do not allow distinguishing between aryl and methyl substituted PPO. On the other hand, proton nuclear magnetic resonance ( H NMR) and infrared (IR) spectroscopy provide more information on the structure of SPPO. These techniques can also be used for determination of the DS of SPPO. 

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