Polyamides and polyesters containing 2,4:3,5‐di‐O‐methylene‐L‐idaroyl residues

Electrochemical oxidation of 2,4:3,5-di-O-methylene-D-gluconic acid in strong alkaline medium afforded a mixture of 2,4:3,5-di-O-methylene-D-glucaric acid 4 and 2,4:3,5-di-O-methylene-L-idaric acid 1 in a 1/8 ratio with a current efficiency of 53%. Force-field calculations using Allinger's molecular mechanics program MM2p85 on 1 and 4 indicate that these cis-fused tetrahydro-[1,3]dioxino[5,4-d]-1,3-dioxin ring systems possess an O-inside conformation with a steric energy of 110.3 and 123.5 kJ·mol−1, respectively. Their conformation was confirmed by 400-MHz 1H- and 100-MHz 13C NMR measurements. A series of polycondensates were prepared by homogeneous solution polymerisation of 1 with an aromatic diol or aromatic diamine, which were analyzed by DSC and TGA.