Binding Profiles for Oligoethylene Glycols and Oligoethylene Glycol Monomethyl Ethers and an Assessment of Their Abilities To Catalyze Phase-Transfer Reactions

Article abstract of DOI:10.1021/jo00165a011

The equilibrium binding or stability constants (K₈) between Na⁺ and oligoethylene glycols , monomethyl ethers , and dimethyl ethers have been determined in anhydrous methanol solution.The ranges of compounds involved are as follows: diols, n = 3-312; monoethers, n = 6-15; diethers, n = 3-21.Although the slopes vary some from species to species, the plot of log K₈ vs. log molecular weight is an essentially straight line.There is no peak in binding observed when a particular number of oxygens might be present to provide, for example, an octahedron of donor groups or a quasi-crown coil.The molecular weight is not crucial to the binding since equal weights of different glycols afford the same net sodium binding.This similarity does not extend to reactivity in the liquid-liquid phase-transfer catalytic system in which it appears that one molecule of polyethylene glycol derivative effects one reaction at a time.Thus equal weights of shorter chains are much more effective than longer chain lengths of similar species.