Lanthanide(III)-catalysed addition of glycolate to maleate. Investigation of intermediates using multinuclear magnetic resonance spectroscopy
- 1 January 1988
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 11,p. 2723-2728
- https://doi.org/10.1039/dt9880002723
Abstract
The lanthanum(III)-catalysed addition of glycolate to maleate to yield carboxymethoxysuccinate(3–)(cmos) is described. It is shown that the reaction only proceeds above pH 6, indicating the formation of di-ionised glycolate as a pre-equilibrium for the rate-limiting step, i.e. the addition of the CH2–O– to the olefinic bond. Due to strong complexation of LaIII by the product cmos, the reaction requires one LaIII ion per two cmos formed. The inhibitory effects of non-reacting strong chelators such as ethylenediaminetetra-acetate, nitrilotriacetate, and 2,6-pyridinedicarboxylate indicate the formation of mixed-ligand complexes leading to the addition reaction. This has been confirmed by GdIII-induced 13C relaxation rate enhancements, and DyIII-induced 17O shift measurements.Keywords
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