Crown ether acetals: synthesis and characterisation of a family of novel oxygen macrocyclic compounds

Abstract

The synthesis of cyclic acetals containing a repetitive –CH₂CH₂O–grouping within the ring is described. Compounds with rings of up to thirty-four members and with one or two acetal groups have been prepared and characterised by their ¹H and ¹³C n.m.r. spectra, the amount of acetaldehyde released on hydrolysis, and their molecular weights. The general formulae of the new compounds are CH₃[graphic omitted] with n= 2—6; CH₃[graphic omitted], with n= 2—5; R[graphic omitted] with R = Pr, Prⁱ, Ph; and [graphic omitted], with n= 0, 1, 2. As precursors for compounds related to the last of these series, the new open-chain dichloroacetals CH₃CH[(OCH₂-CH₂)_nCl]₂, with n= 2, 3 were prepared. Rate constants for the acid-catalysed hydrolysis of some of the new acetals are reported.