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Titration of fatty acids in sugar-derived (APG) surfactants: A C-13 NMR study of the effect of headgroup size, chain length, and concentration on fatty acid pKa at a nonionic micellar interface

Whiddon, Christy LU ; Bunton, C A and Söderman, Olle LU (2003) In The Journal of Physical Chemistry Part B 107(4). p.1001-1005
Abstract
The pK(a) of a C-13-enriched fatty acid probe, tetradecanoic acid, was investigated in a variety of sugar-derived (APG) surfactants by using C-13 NMR to monitor the chemical environment of the probe during titration with base. There was an increase of approximately 2 pK(a) units for the probe within the micellar systems compared to the value of acetic acid in water. Analysis shows that the interfacial environment of alkylglucoside surfactants is similar to, although slightly more polar than, that of ethylene glycol-derived (EO) nonionic surfactants, and there is no indication that the alkylglucoside surfactants are deprotonated at pH levels between 2 and 10. The average pK(a) of the fatty acid probe in the APGs is measured to be 6.3, and... (More)
The pK(a) of a C-13-enriched fatty acid probe, tetradecanoic acid, was investigated in a variety of sugar-derived (APG) surfactants by using C-13 NMR to monitor the chemical environment of the probe during titration with base. There was an increase of approximately 2 pK(a) units for the probe within the micellar systems compared to the value of acetic acid in water. Analysis shows that the interfacial environment of alkylglucoside surfactants is similar to, although slightly more polar than, that of ethylene glycol-derived (EO) nonionic surfactants, and there is no indication that the alkylglucoside surfactants are deprotonated at pH levels between 2 and 10. The average pK(a) of the fatty acid probe in the APGs is measured to be 6.3, and it is argued that this value

s an appropriate choice for pK(a)(0), the intrinsic dissociation constant for an acid at a hydrophobic/hydrophilic interface, when calculating the surface potential of charged systems. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
The Journal of Physical Chemistry Part B
volume
107
issue
4
pages
1001 - 1005
publisher
The American Chemical Society
external identifiers
  • wos:000180649100016
  • scopus:0037473032
ISSN
1520-5207
DOI
language
English
LU publication?
yes
id
ac030ea8-c97e-4171-8df1-3a1ac80baf18 (old id 122271)
date added to LUP
2007-07-12 14:21:16
date last changed
2018-05-29 09:51:35
@article{ac030ea8-c97e-4171-8df1-3a1ac80baf18,
  abstract     = {The pK(a) of a C-13-enriched fatty acid probe, tetradecanoic acid, was investigated in a variety of sugar-derived (APG) surfactants by using C-13 NMR to monitor the chemical environment of the probe during titration with base. There was an increase of approximately 2 pK(a) units for the probe within the micellar systems compared to the value of acetic acid in water. Analysis shows that the interfacial environment of alkylglucoside surfactants is similar to, although slightly more polar than, that of ethylene glycol-derived (EO) nonionic surfactants, and there is no indication that the alkylglucoside surfactants are deprotonated at pH levels between 2 and 10. The average pK(a) of the fatty acid probe in the APGs is measured to be 6.3, and it is argued that this value <br/><br>
s an appropriate choice for pK(a)(0), the intrinsic dissociation constant for an acid at a hydrophobic/hydrophilic interface, when calculating the surface potential of charged systems.},
  author       = {Whiddon, Christy and Bunton, C A and Söderman, Olle},
  issn         = {1520-5207},
  language     = {eng},
  number       = {4},
  pages        = {1001--1005},
  publisher    = {The American Chemical Society},
  series       = {The Journal of Physical Chemistry Part B},
  title        = {Titration of fatty acids in sugar-derived (APG) surfactants: A C-13 NMR study of the effect of headgroup size, chain length, and concentration on fatty acid pKa at a nonionic micellar interface},
  url          = {http://dx.doi.org/},
  volume       = {107},
  year         = {2003},
}