Hydration and ion association of aqueous choline chloride and chlorocholine chloride. Issue 21 (20th May 2019)

• Record Type: Journal Article
• Authors: Shaukat, Saadia; Fedotova, Marina V.; Kruchinin, Sergey E.; Bešter-Rogač, Marija; Podlipnik, Črtomir; Buchner, Richard
• Is Part Of: Physical chemistry chemical physics. Volume 21:Issue 21(2019)
• Page Start: 10970
• Page End: 10980
• Publication Date: 2019-05-20
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c9cp01016e
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Choline hydration occurs predominantly via its hydroxyl group, and weak contact ion pair formation with Cl − is via the onium moiety. Abstract : The choline ion (Ch + ) is ubiquitous in nature and also its synthetic homologue, chlorocholine (ClCh + ), is widely used. Nevertheless, surprisingly little information on the hydration and counter-ion binding of these cations can be found in the literature. In this contribution we report effective hydration numbers, determined by dielectric relaxation spectroscopy, and ion-pair association constants with Cl −, determined by dilute-solution conductivity measurements. In combination with RISM calculations the obtained data suggest that for Ch + water is bound to the hydroxy group via hydrogen bonds whereas for ClCh + a rather stiff clathrate-like shell around the chlorine atom seems to be formed. With Cl − both cations form contact ion pairs with association constants of only ∼2 to 3 M −1 .