Chemical Models for Aqueous Biodynamical Processes
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Issue Date
1975-05Author
Mata-Segreda, Julio F.
Publisher
University of Kansas
Format
171
Type
Dissertation
Degree Level
Ph.D.
Discipline
Chemistry
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This item is protected by copyright and unless otherwise specified the copyright of this thesis/dissertation is held by the author.
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Show full item recordAbstract
The proton inventory method was applied to the study of three
processes: the viscous flow of water, the neutral hydrolysis of
esters, and the exchange reaction between aqueous sodium ion and the
carboxylic exchanger Amberlite CG-50®.
The fluidity (1/viscosity; of mixtures of protium and deuterium
oxides at 298.16 K can be described by the equation $ = $ (1 ~ n + 0.90n)
J ^ n o
This result indicates that two protons contribute equally to the overall
isotope effect. The proposed mechanism for momentum transfer involves
an interstitial water molecule linked to "flowing" molecular sheaths.
The rate constants of neutral hydrolysis of ethyl trifluoroacetate
at 298.16 K can be described by the equation k = k (l-n+0.47n) (l-n+0. 78«)
n o .
This result suggests a catalytic entity with 67% hydronium ion character
which we have called the poena -hydronium ion.
The rate of exchange of the reaction Na(aq)+ + Arnberlite CG-50®
4.
was found to be independent of a) [Na ] / (resin) ; b) hydrodynamic condi-
4- -j- -ftions;
c) nature of cation (Li , Na , K ) . The solvent isotope effect
for Na and K exchange was found to be 3.06 ± 0.17 and 3.31 i 0.38,
respectively. These results suggest that diffusion of the newly exchanged
hydronium ion through the polymeric matrix is rate determining. The
reaction rate constants for sodium exchange in mixtures of H20~D20 at
298.16 K can be described by the equation k = k (1 - n + 0. 70n)3 which
n o
supports the proposed mechanism.
Fractionation factors were measured for four geminal hydroxylic
compounds as models for the tetrahedral intermediate in the hydrolysis
of carboxylic acid derivatives. The values are 1.23 ± 0.08 for chloral
hydrate; 1.24 ± 0.20 for ninhydrin; 1-28 ± 0.17 for D-glucose; and
1.23 ± 0.02 for D-fructose. These values indicate that hydrogens are
more tightly bound in these molecules than in bulk water. A theoretical
calculation of deuterium isotope effects was made on a gem-diol model.
The isotope effect K.JK^ increases with an increase in the hydroxylic
D li
torsional force constant. An extensive table of isotopic fractionation
factors is given.
vi
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