Seven naphthol dyes which were synthesized by diazotization and coupling reactions (substituted anilines→2-naphthol) were treated with sodium hypochlorite at a room temperature under some pH's in a two-phase solvent system of dichloromethane and water.p-OCH₃, H, o-Cl, m-Cl, p-Cl, p-NO₂, and 2, 4-DiCl were selected as substituents. The oxidation-rates were pursued by HPLC, and the structure of the oxidation products were mainly determined by Gas Chromatography/Mass Spectroscopy (GC-MS) as well as by comparison with authentic sample. The following results were obtained:
1. The oxidation products were polychloro-2-naphthols, azobenzenes, azoxybenzenes, diazonium ions (trapped by 2-naphthol), and polychloro compounds of naphthol dyes, regardless of the substituent.
2. In contrast, the remarkable substituent effects on the oxidation-rate were observed: acceleration by the electron-donating methoxy group and retardation of the electron-attracting nitro group.
Judging both from the oxidation product identified and from the relationship between the rate and substituent constant (σ), the decomposition mechanism was proposed that the electrophilic chlorinations toward benzene and/or naphthalene rings took place as well as chloro-dediazotizations under the relatively acidic conditions. By the prolonged oxidation, further chlorination and oxidation of the primary products occurred to afford many products. Finally, it was also proposed that a requisite for an anti-bleaching dye molecule was to contain electron-attracting groups in the dye; the ortho substituent to the azo group was more effective.

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In order to estimate the effect of surfactant on removal of solid particles, polyethylene, polystyrene latex and glass particles adhered to glass plates were removed in the washing device as has already been reported. The force necessary to detach the soils, F_H1/2, was estimated. The particle behavior was analyzed by VTR system and a personal computer. The results were compared with those previously obtained using water without surfactant.
The following results were obtained:
1) The removal percentage increased with surfactant concentration and the duration of washing time, and was proportional to a flow speed.
2) F_H1/2was obtained for glass particles of 4.00μm and 7.60μm, which were estimated as 106 and 233pN, respectively.
3) The behavior of polystyrene latex and glass particles was ascertained to be of the two types that have already been reported, namely A-type removal and B-type removal. For the polyethylene particles, B-type removal was ascertained.
4) The behavior of glass particles was ascertained to be of two types, namely A₁-type removal and A₂-type removal, and the moving speed of particles was dependent on the particle size.
5) The removal percentage under the washing conditions with surfactant was larger than that with water.

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