α-Cyclodextrin affects the acid-base properties of octanoic acid/sodium octanoate

Jorge C. Pereira; Artur J.M. Valente; Olle Söderman

doi:10.1016/j.molliq.2022.119955

α-Cyclodextrin affects the acid-base properties of octanoic acid/sodium octanoate

Jorge C. Pereira, Artur J.M. Valente, Olle Söderman

Physical Chemistry

University of Coimbra

Research output: Contribution to journal › Article › peer-review

Abstract

The interaction of octanoic acid and its conjugate base sodium octanoate with α-cyclodextrin was studied by ¹H NMR and isothermal titration calorimetry, respectively, at 298.15 K. The results are in agreement with a 1:1 stoichiometry in the complex. The binding of octanoate with α-cyclodextrin is characterized by a positive entropy, stressing the relevance of hydrophobic interactions. Based on the host-guest complex formation, the effect of α-cyclodextrin on the acidity behavior of the acid was evaluated by potentiometric titration. The results are interpreted in terms of the Henderson-Hasselbalch equation and by using an analytical equation for the titration curve. The apparent ionization constants of the complexes are higher than those obtained in water, indicating that octanoic acid becomes a weaker acid after complexation.

Original language	English
Article number	119955
Journal	Journal of Molecular Liquids
Volume	364
DOIs	https://doi.org/10.1016/j.molliq.2022.119955
Publication status	Published - 2022

Subject classification (UKÄ)

Organic Chemistry

Free keywords

Acidity
Cyclodextrin
Equilibrium constants
Octanoic acid
pKa

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10.1016/j.molliq.2022.119955

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title = "α-Cyclodextrin affects the acid-base properties of octanoic acid/sodium octanoate",

abstract = "The interaction of octanoic acid and its conjugate base sodium octanoate with α-cyclodextrin was studied by 1H NMR and isothermal titration calorimetry, respectively, at 298.15 K. The results are in agreement with a 1:1 stoichiometry in the complex. The binding of octanoate with α-cyclodextrin is characterized by a positive entropy, stressing the relevance of hydrophobic interactions. Based on the host-guest complex formation, the effect of α-cyclodextrin on the acidity behavior of the acid was evaluated by potentiometric titration. The results are interpreted in terms of the Henderson-Hasselbalch equation and by using an analytical equation for the titration curve. The apparent ionization constants of the complexes are higher than those obtained in water, indicating that octanoic acid becomes a weaker acid after complexation.",

keywords = "Acidity, Cyclodextrin, Equilibrium constants, Octanoic acid, pKa",

author = "Pereira, {Jorge C.} and Valente, {Artur J.M.} and Olle S{\"o}derman",

year = "2022",

doi = "10.1016/j.molliq.2022.119955",

language = "English",

volume = "364",

journal = "Journal of Molecular Liquids",

issn = "0167-7322",

publisher = "Elsevier",

}

TY - JOUR

T1 - α-Cyclodextrin affects the acid-base properties of octanoic acid/sodium octanoate

AU - Pereira, Jorge C.

AU - Valente, Artur J.M.

AU - Söderman, Olle

PY - 2022

Y1 - 2022

N2 - The interaction of octanoic acid and its conjugate base sodium octanoate with α-cyclodextrin was studied by 1H NMR and isothermal titration calorimetry, respectively, at 298.15 K. The results are in agreement with a 1:1 stoichiometry in the complex. The binding of octanoate with α-cyclodextrin is characterized by a positive entropy, stressing the relevance of hydrophobic interactions. Based on the host-guest complex formation, the effect of α-cyclodextrin on the acidity behavior of the acid was evaluated by potentiometric titration. The results are interpreted in terms of the Henderson-Hasselbalch equation and by using an analytical equation for the titration curve. The apparent ionization constants of the complexes are higher than those obtained in water, indicating that octanoic acid becomes a weaker acid after complexation.

AB - The interaction of octanoic acid and its conjugate base sodium octanoate with α-cyclodextrin was studied by 1H NMR and isothermal titration calorimetry, respectively, at 298.15 K. The results are in agreement with a 1:1 stoichiometry in the complex. The binding of octanoate with α-cyclodextrin is characterized by a positive entropy, stressing the relevance of hydrophobic interactions. Based on the host-guest complex formation, the effect of α-cyclodextrin on the acidity behavior of the acid was evaluated by potentiometric titration. The results are interpreted in terms of the Henderson-Hasselbalch equation and by using an analytical equation for the titration curve. The apparent ionization constants of the complexes are higher than those obtained in water, indicating that octanoic acid becomes a weaker acid after complexation.

KW - Acidity

KW - Cyclodextrin

KW - Equilibrium constants

KW - Octanoic acid

KW - pKa

U2 - 10.1016/j.molliq.2022.119955

DO - 10.1016/j.molliq.2022.119955

M3 - Article

AN - SCOPUS:85135378823

SN - 0167-7322

VL - 364

JO - Journal of Molecular Liquids

JF - Journal of Molecular Liquids

M1 - 119955

ER -

α-Cyclodextrin affects the acid-base properties of octanoic acid/sodium octanoate

Abstract

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