SYNTHESES OF AMPHIPHILIC BENZOTHIAZOLIUM AZO DYES AND BEHAVIOR OF THEIR MONOLAYERS ON A WATER-SURFACE

Syntheses of several 2-(4-alkylaminophenylazo)-N-methylbenzothiazolium perchlorates having octadecyl groups were carried out in order to investigate the spreading properties of the monolayers on a water surface. These amphiphilic azo dyes were prepared by the reaction of N-octadecylated aromatic amines with a 3-methyl-2-benzothiazolinone hydrazone hydrochloride in acetic acid containing lead dioxide. When the chloroform solution containing the dyes was developed on water, it found that the dyes formed stable monolayers at the air-water interface, respectively. From the results of pi-A isotherms and occupied molecular area measurements, it can be considered that the chromophores appear to be oriented in the monolayer, having a degree of c. 80-85-degrees to the water surface. The degree of the orientation in the mixed monolayers with arachidic acid (AA) are only slightly larger than that in the pure monolayer systems.