O.A. Zakurdaeva

Distribution of benzo-substituted crown-ethers between chloroform and water: effects of macrocycle ring size and lithium chloride

AbstractSmall size benzo-substituted crown ethers are attractive complexing agents for lithium isotope separation by solvent extraction. Low transfer of the crown ethers from solvent to water is a key point for applicability of the extractants. In the present study, 9- and 12-membered crown ethers were synthesized, and their distribution between chloroform and water was studied. Polyether ring size, benzene substituents and addition of LiCl to water were found to effect on distribution constants. Low losses of the macrocycles were observed at single-stage contact with aqueous phase. However, these losses should be taken into account in the design of multistage processes for the preparation of highly enriched lithium isotopes.

Radical intermediates of low temperature radiolysis of di-tert-butylcyclohexano-18-crown-6/1-octanol extractant

Abstract Intermediates of low temperature (77 K) X-rays radiolysis of 1-octanol and di-tert-butylcyclohexano-18-crown-6 solutions in 1-octanol were studied by ESR spectroscopy. Hydroxyalkyl CH3(CH2)6C•HOH and interior-type alkyl R1C•HR2OH radicals were found to be main paramagnetic products stabilized in 1-octanol irradiated at 77 K. In addition to abovementioned radicals, macrocyclic –O–CH2–C•H– and acyclic –C•H–C(H)=O radicals produced from crown ether were identified in irradiated 1.0 M DtBuCH18C6 solution in octanol. No deviation in radiation-chemical yield of the stabilized acyclic radicals from the value expected in accord with “additive” rule was observed in the latter case. It was supposed that macrocycle cleavage in DtBuCH18C6 occurred at early stages of radiolysis rather than in secondary radical reactions between products of 1-octanol radiolysis and crown ether. Meanwhile, alkyl radicals formed from 1-octanol can react with crown ether, resulting in formation of macrocyclic products of radiolysis.