TY - JOUR
T1 - Measurement of the dimerization equilibrium constants of enantiomers
AU - Baciocchi, Renato
AU - Zenoni, Gianmarco
AU - Valentini, Massimiliano
AU - Mazzotti, Marco
AU - Morbidelli, Massimo
PY - 2002/10/31
Y1 - 2002/10/31
N2 - 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.
AB - 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.
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U2 - 10.1021/jp020352n
DO - 10.1021/jp020352n
M3 - Article
AN - SCOPUS:0037206755
SN - 1089-5639
VL - 106
SP - 10461
EP - 10469
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
IS - 43
ER -