Abstract
The family of dipotassium glycyrrhizinate (GK2) catalyzes the hydrolysis of nonionic ester surfactants (NES), such as hydrogenated castor oil with 60 oxyethylene units attached (HCO-60) and monostearate with 25 oxyethylene units attached (SA-25), even in the pH range of 3–6, where NES are generally stable in the absence of GK2. Long-chain fatty acids also accelerate the hydrolysis reaction. Analyses, based on circular dichroism spectroscopy, and empirical force field calculations suggest that a GK2 and an NES molecule form an energetically stable complexvia hydrophobic interactions in which the ester carbonyl is in close contact with either one of the three different carboxyl groups in GK2, acting as an acid catalyst.
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Koide, M., Takahashi, M., Tamagaki, S. et al. Catalytic effect of dipotassium glycyrrhizinate on the hydrolysis of nonionic ester surfactants. J Am Oil Chem Soc 73, 913–920 (1996). https://doi.org/10.1007/BF02517995
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DOI: https://doi.org/10.1007/BF02517995