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Catalytic effect of dipotassium glycyrrhizinate on the hydrolysis of nonionic ester surfactants
Author(s) -
Koide Misao,
Takahashi Masahiko,
Tamagaki Seizo,
Tagaki Waichiro
Publication year - 1996
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/bf02517995
Subject(s) - hydrolysis , chemistry , catalysis , organic chemistry , molecule , circular dichroism , ester hydrolysis , polymer chemistry , castor oil , stereochemistry
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 complex via 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.