86619-00-3Relevant academic research and scientific papers
Molecular Desidn of Crown Ethers. 4. Syntheses and Selective Cation Binding of 16-Crown-5 and 19-Crown-6 Lariats
Ouchi, Mikio,Inoue, Yoshihisa,Wada, Kazuhito,Iketani, Shin-ichi,Hakushi, Tadao,Weber, Edwin
, p. 2420 - 2427 (2007/10/02)
A number of new lariat 16-crown-5 and 19-crown-6 ethers posesing a variety of single or double side arm(s) were synthesized, and their cation-binding abilities were evaluated by solvent extraction technique.In general, the extractabilities of the 16-crown-5 lariats for most mono- and divalent cations increased gradually with extending oxyethylene side arm.However, sodium and silver ions, which are best size fitted to the crown cavity, showed peac extractability/selectivity at a specific length of the donating side arm.The complexation stoichiometry is 1 : 1 forall cations employed as confirmed by measurement of the extraction equilibrium constants for the single-armed 16-crown-5 (3p).The tetrasubstituted pivot carbon is shown to be a reguirement for lariat 16-crown-5 to effect extra side-arm ligation, although the second side arm of lariat ether 3e seems ineffective in extractability enhancement with reference to the single-armed analogue 3p.By contrast, the corresponding 19-crown-5 lariat with potential donor side arms at an appropiate position did not show any enhancement in extractability for most cations, which may be attributed to its flexible framework.
Chemistry of crown ethers XIX. Functionalized crown ethers for the solubilization of barium sulfate
Jong, F. de,Zon, A. van,Reinhoudt, D. N.,Torny, G. J.,Tomassen, H. P. M.
, p. 164 - 173 (2007/10/02)
The use of seawater as injection fluid in oil-producing formations often leads to blocking of the wells as a result of barium sulfate-scale formation.Macrocylic complexants specifically designed to solubilize barium sulfate efficiently into water have been synthesized and their BaSO4-solubilizing capacities have been determined.The stability of barium complexes of macrocyclic polyethers can be greatly increased by the introduction of flexible side-chains containing anionic groups.Most of newly synthesized complexants, based mainly on diaza-18-crown-6, give very stable complexes.However, many o f them are extremely insoluble in water.Only bis(carboxymethyl)diaza-18-crown-6, bis(phosphonomethyl)diaza-18-crown-6 and, to a lesser extent, bis(dicarboxymethyl)diaza-18-crown-6 and bisdiaza-18-crown-6 are efficient solubilizers of BaSO4 in water.
