Tg. Levitskaia et al., Synthesis, structure, and extraction behavior of 4,5',4 '' 5 '''-tetra-tert-butyltetrabenzo-24-crown-8, J CHEM S P2, (5), 2001, pp. 808-814
Citations number
46
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2
Isomerically pure 4,5',4",5"'-tetra-tert-butyltetrabenzo-24-crown-8 was syn
thesized by a route that eliminates any need for isomer separation. Its str
ucture was determined using single crystal X-ray diffraction methods. Since
the observed saddle-shaped conformation of the crown ether is the same as
previously reported for the closely related tetrabenzo-24-crown-8, the pres
ence of the peripheral tert-butyl groups has no apparent effect on ring str
ucture. This structure experiences few intermolecular interactions beyond L
ondon forces, suggesting it represents a low energy conformation. Liquid-li
quid distribution behavior of CsNO3 and CsClO4 between water and 1,2-dichlo
ro-ethane (1,2-DCE) containing 4,5',4",5"'-tetra-tert-butyltetrabenzo)-24-c
rown-8 was investigated. Equilibrium constants corresponding to the extract
ion of ion pairs and dissociated ions, formation of the caesium complex, an
d dissociation of the ion pairs in water-saturated 1,2-DCE at 25 degreesC w
ere obtained from equilibrium modeling using the SXLSQI program. 4,5',4",5"
'-Tetra-tert-butyltetrabenzo-24-crown-8 exhibits stronger caesium binding a
nd a similarly low tendency towards ion-pairing, in comparison with the pre
viously characterized isomeric 4,4'- and 4,5'-di-tert-octyltetrabenzo-24-cr
own-8 ethers.