8-Hydroxyquinoline-5-sulfonic acid 를 alkali 媒質에서 $10^{circ}C$以下로 維持하여 nitroso 化시켜 7-nitroso-8-hydroxy-quinoline-5-sulfonate (NHQS)를 合成하였으며 그 酸解離定數를 分光光度法과 pH滴定法에 依하여 測定하였다. 두 方法에 依하여 近似하게 같은 값은 얻어졌고 이것들은 8-hydorxyquinoline의 該當 pK값에 比해 작다. 8-hydroxyquinoline에 比해 NHQS의 낮은 鹽基性은 導入된 電子吸引性基들의 影響으로 생각되며 特히 nitroso 基는 ortho位의 phenol性 OH基의 酸性度의 增加에 많은 影響을 주는 것으로 생각된다.
7-Nitro-8-hydoxyquinoline-5-sulfonate (NHQS) have been synthesized from 8-hydroxyquinoline-5-sulfonic acid by nitrosation in alkaline medium at temperature below $10^{circ}C$ and the acid dissociation constants of NHQS have been determined by spectrophotometric and potentiometric methods. Almost same values are obtained by both methods but the values are lower than the corresponding 8-hydroxyquinoline. The lower basicity of NHQS is considered as the effect of electron withdrawing groups, especially adjacent nitroso group.
