2,5-DIALKOXY SUBSTITUTED OLIGO(1,4-PHENYLENEETHENYLENE)S AND POLY(1,4-PHENYLENEETHENYLENE)S

O-Alkylation and regioselective Rieche formylation of 2-methylhydroquinone (1) yields the 2,5-dialkoxy-4-methylbenzaldehydes 4a-j. The corresponding azomethines 5a-j enter in a strongly alkaline medium a self-condensation reaction leading to the title compounds 6/7a-j. These conjugated oligomers and polymers possess highly regular structures with exclusively (E)-configurated double bonds. GPC, IR, H-1-, C-13-NMR and MS-FD measurements were used for their characterization. Somewhat different results were obtained for the similarly prepared Schiff base 51 which contains chlorine substituents in the side chains. Cleavage of hydrogen chloride leads not only to unsaturated alkoxy groups; additionally, cyclization reactions (51 --> 81) are observed.