Enthalpy characteristics of dissolution of <Emphasis Type="SmallCaps">l</Emphasis>-cysteine and <Emphasis Type="SmallCaps">l</Emphasis>-asparagine in aqueous solutions of acetonitrile and dimethyl sulfoxide at 298.15 K |
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Authors: | I N Mezhevoi V G Badelin |
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Institution: | (1) Institute of Solution Chemistry, Russian Academy of Sciences, 1, Academicheskaya str., 153045 Ivanovo, Russia |
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Abstract: | The integral enthalpies of dissolution Δsol
H
m of l-cysteine and l-asparagine in mixtures of water with acetonitrile and dimethyl sulfoxide at the concentration of organic solvent up to 0.32
molar fractions were measured by means of dissolution calorimetry. The standard enthalpies of dissolution (Δsol
H°) and transfer (Δtrans
H°) of the amino acids from water to a mixed solvent were calculated. The enthalpy coefficients of pair interactions for L-cysteine
and L-asparagine with cosolvent molecules are positive, except for the L-asparagine-water-acetonitrile system. The concepts
on the prevailing effect of specific interactions in solutions and the influence of the nature of the cosolvents and lateral
substituents of the amino acids on the thermochemical characteristics of dissolution were used to explain the data obtained. |
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Keywords: | |
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