Among bis-substituted derivatives of sodium 4, 4′-diaminostilbene 2, 2′-disulfonate (1), the following types of fluorescent whitening agents were synthesized : acylamide type (3; with an unconjugated substituent group adjacent to the carbonyl group, (3) -a ; with a conjugated substituent group, (3) -b), ureide type (5), triazinylaminotype (8), and naphthotriazole type (10).
Solution of each derivative of 1.00×10
-5 mol/
l was irradiated at 30±0.2°C for one hour under UV light (360 mμ). The UV absorption and fluorescence spectra of the solutions were also examined before and after the irradiation.
Results : In view of fluorescence intensity and stability to light in solution, these derivatives were classified into three types.
1. Derivatives whose fluorescence intensity increases with the value of ε
max, but with poor photostability… (3) -a, (5), (8).
2. Derivatives whose fluorescence intensity and the value of ε
max are both large, and with good photostability… (10).
3. Derivatives whose fluorescence intensity is very poor considering the value of ε
max, but with good photostability… (3) -b.
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