Process for the production of 2-stilbylnaphthotriazole optical bleaches
AssigneeCiba-Geigy Corporation
InventorsRichard B. Lund, Larry W. Bass
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Abstract
An improved process for the production of 2-stilbylnaphthotriazole optical bleaches which involves diazotizing aminostilbene 2-sulfonic acids, coupling the thus formed diazonium salt with naphthylamino-sulfonic acid to form the stilbylnaphthyl monoazo salt by adding the naphthylamino-sulfonic acid to the diazonium salt from the diazotization, neutralized to a pH in the range of 6-8, in the presence of 2-butoxyethanol, oxidizing said monoazo salt to form the 2-stilbylnaphthotriazole compounds with air in an aqueous alkaline medium containing butoxyethanol and isolating and recovering said 2-stilbylnaphotriazole optical bleaches as their sodium salts.
Claims4
In a process for preparing a 2-stilbylnaphthotriazole optical bleach having the steps of:
- (a) diazotizing an aminostilbene 2-sulfonic acid;
- (b) coupling the thus formed diazonium salt with a naphthylamino-sulfonic acid to form a stilbylnaphthyl monoazo salt;
- (c) oxidizing said monoazo salt to form a 2-stilbylnaphthotriazole compound;
- and
- (d) isolating and recovering said 2-stilbylnaphthotriazole optical bleach as its sodium salt;
- the improvement comprising the step of conducting said coupling (b) by adding said naphthylaminosulfonic acid to said diazonium salt from the diazotization, neutralized to a pH in the range of 6-8 and maintaining the pH in the range of 6-8, in the presence of 2-butoxyethanol as a solvent for the organic reactants and products.
Dependencies are inferred from the claim text.