Figure 4. Complex behaviour of a dynamic orthoester system.

Structures of predominant products as a function of time, template and other chemical stimuli. Reaction conditions: trimethyl orthoacetate (120 μmol), diethylene glycol (180 μmol), metal salt (60 μmol), TFA (0.6 μmol added per day), MS (4 Å, 1 g), CDCl₃ (6.0 ml), room temperature. Eight-membered ring products (3 for R=Me) could be quantitatively converted into cryptate [Na⁺⊂o-Me₂-1.1.1]X⁻ and vice versa. Pristine cryptand o-Me₂-1.1.1 could be prepared using anion exchange resin Lewatit MP64 (chloride form). Cryptand o-Me₂-1.1.1 could be transformed into lithium cryptate [Li⁺⊂o-Me₂-1.1.1]X⁻ and from there back into [Na⁺⊂o-Me₂-1.1.1]X⁻. NaX: NaBArF; LiX: LiTPFPB (lithium tetrakis(pentafluorophenyl)borate); KX: KBArF; M⁺: mixture of Na⁺ with residual Li⁺ or K⁺ due to cation exchange with MS.