Gel Permeation Chromatography of Alkali Cations in Methanol Effect Of Macromolecular Ligands on the Volume of Elution

Abstract

L a b o r e t o i r e de C h i m i e O r g a n i q u e de S y n t h P s e . U n i v e r s i t b C a t h o l i q u e de L o u v a i n , P l a c e L. P a s t e u r , 1 . B-1 3 4 8 Louvain-La-Neuve. BELGIUM S U M M A R Y T h e gel permeation of low c o n c e n t r a t i o n s of s a l t s of a l k a l i m e t a l s on S e p h a d e x LH-20 using methanol-acetic acid a s e l u e n t allowed r e s o l u t i o n of binary m i x t u r e s of t h e salts. T h e a d d i t i o n of poly(ethyleneglyco1) m o n o m e t h y l ether (M.W. 5000) ( P E G ) t o t h e m o b i l e phase induced a l a r g e r e d u c t i o n of t h e v o l u m e o f e l u t i o n o f potassium and r u b i d i u m but s o d i u m w a s l i t t l e affected. A PEG-18-crown-6 c o n j u g a t e w a s synthesized and t h e a s s o c i a t i o n c o n s t a n t s of t h e c r o w n with v a r i o u s c a t i o n s w e r e determined. T h e PEG-crown c o n j u g a t e did not further a c c e l e r a t e t h e c a t i o n s a s compared t o P E G alone.

Supramolecular complexes: Determination of stability constants on the basis of various experimental methods

“…In a series of macrocycles for which the logK values were measured in MeOH, the correlation relationship is found between the cor responding stability constants of complexes (M + )L of [158][159][160][161] and can be used for determination of the stability constants of complexes of the benzylammonium cation with mac rocyclic ligands in methanol, if similar data are known for the sodium or potassium cation or vice versa. This is of interest, as there are few data in the literature [ [162], respectively. Replacement of only one oxygen atom in 18 crown 6 by a CH 2 group at a transition to 18 crown 5 results in a decrease in the stability constant by two to three orders in magnitude in MeOH (Tables 9, 10, and 12) for com plexes (M + )L of Na + , K + , and BzN cations.…”