Naslov
NMR Spectroscopic Characterization of Acid-base Equilibria in Aprotic Organic Solvents

Autori
Bregović, Nikola ; Barišić, Dajana ; Tomišić, Vladislav

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Adriatic NMR Conference 2017 : Book of Abstracts / Namjesnik, Danijel ; Pičuljan, Katarina ; Bregović, Nikola ; Novak, Predrag - Zagreb : Kemijski odsjek Prirodoslovno-matematičkog fakulteta Sveučilišta u Zagrebu ; Geološki odsjek Prirodoslovno-matematičkog fakulteta Sveučilišta u Zagrebu, 2017, 26-26

ISBN
978-953-6076-41-3

Skup
Adriatic NMR Conference

Mjesto i datum
Mali Ston, Hrvatska, 16.06.2017. - 18.06.2017

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
NMR ; acid-base equilibria ; aprotic organic solvents ; aromatic urea derivatives

Sažetak
Acid-base reactions are ubiquitous in chemistry, often playing the key role in biological systems, in the development of new pharmaceuticals or materials, etc. Although (de)protonation reactions in water are among the most studied equilibria, analogous investigations in non-aqueous media are rather scarce. This is partly due to experimental difficulties regarding the potentiometric measurement of pH, but also because the complexity of the corresponding equilibrium systems increases in such solutions. Namely, the protonation constants are much higher in organic solvents in comparison to water, and many acids are prone to homoconjugation (interaction with their conjugated bases) and dimerization. NMR spectroscopy has been extensively used as a tool for quantitative thermodynamic characterization of diverse reactions. However, its utilization for the study of (de)protonation equilibria commonly includes measurement of pH (pD) dependence of 1H NMR spectra, and it is in most cases limited to aqueous systems. In this work, the characterization of acid-base behavior of rather important and extensively studied organic (acetic acid) and inorganic (phosphoric acid) acids in dimethyl sulfoxide and acetonitrile was carried out by means of several experimental methods (UV and NMR spectroscopies, ITC, and conductometry). In addition, the deprotonation of aromatic urea derivatives acting as anion receptors was studied in DMSO using competitive NMR titrations. The focus of the talk will be on the results obtained by NMR spectroscopy which will be compared to those gathered by other techniques. The concepts, advantages, and limitations of the NMR-spectroscopic investigations of proton transfer, homoconjugation, and dimerization equilibria of the studied systems will be discussed in detail.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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