Measurement of the dimerization equilibrium constants of enantiomers

Renato Baciocchi, Gianmarco Zenoni, Massimiliano Valentini, Marco Mazzotti, Massimo Morbidelli*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)

Abstract

The formation of homochiral and heterochiral dimers in solutions of enantiomers causes a number of remarkable phenomena, such as the enantiomeric enrichment of nonracemic mixtures on achiral chromatographic columns when chiral monomers and dimers exhibit different retention behavior. In this work, such effects on optical rotation and UV absorbance are analyzed theoretically and experimentally. In particular, it is demonstrated how optical rotation measurements can be used to estimate the dimerization equilibrium constants. It is shown how significant this is for polarimeter calibration, as well as for the determination of enantiomer concentrations in process streams, when optical rotation and UV absorbance measurements are combined. All experimental measurements refer to the enantiomers of the chiral 2,2'-dihydroxy-1,1'-binaphthyl in chloroform, at a temperature of 23 °C. The measured values of its dimerization equilibrium constants are 1.3 ± 0.5 and 3.1 ± 1.0 L/mol for the formation of homochiral and of heterochiral dimers, respectively.

Original languageEnglish
Pages (from-to)10461-10469
Number of pages9
JournalJournal of Physical Chemistry A
Volume106
Issue number43
DOIs
Publication statusPublished - Oct 31 2002

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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