Chemistry of crown ethers: Synthesis of crown ethers derived from α,γ‐and α,δ‐bis(halomethyl)‐ or α,γ‐bis(hydroxymethyl)‐substituted aromatics

Three series of novel crown ethers have been prepared in which polyether rings of various sizes are linked to a benzene ring through the 1,3‐ or 1,4‐positions or to a furan ring through the 2,5‐positions. They were synthesized from the corresponding α,γ‐ or α,δ‐bis(halomethyl)‐substituted aromatics by reaction with polyethylene glycol disalts or from the disalts of bis(hydroxymethyl)‐substituted aromatics by reaction with polyethylene glycol ditosylates. Both 1:1 (2−67 % yield) and 2:2 (6−30% yield) cyclic reaction products were formed. The fact that the above compounds, which may contain up to 31 ring atoms, are obtained in such high yields without operating at high dilution is connected with the relationship between the chain length of the polyethylene glycol and the diameter of the cation used in the synthesis (template effect).