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

O-Alkylation and regioselective Rieche formylation of 2-methylhydroqui none (1) yields the 2,5-dialkoxy-4-methylbenzaldehydes 4a-j. The corre sponding azomethines 5a-j enter in a strongly alkaline medium a self-c ondensation reaction leading to the title compounds 6/7a-j. These conj ugated oligomers and polymers possess highly regular structures with e xclusively (E)-configurated double bonds. GPC, IR, H-1-, C-13-NMR and MS-FD measurements were used for their characterization. Somewhat diff erent results were obtained for the similarly prepared Schiff base 51 which contains chlorine substituents in the side chains. Cleavage of h ydrogen chloride leads not only to unsaturated alkoxy groups; addition ally, cyclization reactions (51 --> 81) are observed.