Solvent Effects on the Monomer/Hydrogen‐Bonded Dimer Equilibrium in Carboxylic Acids: (+)‐(S)‐Ketopinic Acid as a Case Study |
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| Authors: | Dr Pilar Gema Rodríguez?Ortega Prof Manuel Montejo?Gámez Prof Fernando Márquez?López Prof Juan Jesús López?González |
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| Institution: | 1. Department of Physical and Analytical Chemistry, University of Jaén, Jaén, Spain;2. Department of Chemistry, University of Antwerp, Antwerp, Belgium |
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| Abstract: | The hydrogen‐bond‐assisted self‐association process of a chiral semirigid carboxylic acid, namely, (+)‐(S)‐ketopinic acid, has been studied. The multiconformational monomer/dimer equilibrium has been evaluated by means of a concentration‐dependent FTIR study that enabled the experimental equilibrium constants of the dimer formation reaction (Kdim) to be determined in two solvents of different polarity. In CDCl3, dimeric forms predominate, even in diluted solutions ( =5.074), whereas in CD3CN the self‐association process is hindered and monomers are always the main species, irrespective of solute concentration ( =0.194). The reliability of the dimerization constants and the derived mono‐ and dimeric experimental fractions have been proven by means of accurate matching between the experimental vibrational circular dichroism spectra of the species and the theoretical spectra generated by considering the simultaneous weighted contributions of the concomitant monomers and dimers. |
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| Keywords: | carboxylic acids crystal growth density functional calculations hydrogen bonding self-association |
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