SYNTHESIS AND LIGHT-ABSORPTION OF BENZOTELLURAZOLE CROWN-ETHER CYANINE DYE

Various methods for synthesis of 2-methyl-5,6-(1,4, 7,10,13-pentaoxatridecamethylene)benzotellurazole (8) are described. Under different conditions, alkylation of compound 8 with methyl iodide gave telluronium salt 1,2-dimethyl-5,6-(1,4,7,10,13-pentaoxatridecamethylene)benzotellurazolium iodide (15) or quaternary ammonium salt 2,3-dimethyl-5,6-(1,4,7,10,13-pentaoxatridecamethylene)benzotellurazolium iodide (14) in high yields, repectively. The cyanine dye 3,3'-dimethyl-5,6,5',6'-bis(1,4,7,10,13-pentaoxatridecamethylene)telluracarbocyanine iodide (16) is obtained by condensation of 14 with ethyl orthoformate in acetic anhydride, The visible absorption of the cyanine dye is also discussed.