2-Formylbenzenesulfonic acid sodium salt (Sodium o-sulfonate benzaldehyde) is the primary intermediate for synthesizing fluorescent whitening agent CBS, triphenylmethane dye, and moth-repellent N. Fluorescent whitening agent CBS is a new fluorescent whitening agent. It has excellent resistance to chlorine bleaching, acid and alkali resistance, and sunlight resistance. It is an ideal additive for light, textile, and daily chemical industries, mainly used in washing powders, laundry pastes, soaps, toilet soaps, and liquid detergents. Improve the performance of the product, improve the intrinsic quality and appearance quality of the product. Industrially, 2-Formylbenzenesulfonic acid sodium salt is usually obtained by sulfonating sodium sulfite in water with o-chlorobenzaldehyde as the raw material and potassium iodide as the catalyst. The catalyst can be potassium iodide, sodium iodide, and other inorganic substances containing iodide ions.
It forms prisms or plates by extracting with boiling EtOH, filtering, evaporating to dryness and recrystallising the Na salt from a small volume of H2O. The N-phenylhydrazone sodium salt recrystallises from H2O with m 174.5o. [Gnehm & Schüle Justus Liebigs Ann Chem 299 363 1898, Beilstein 11 IV 652.]
