In the present research, the use of 2-(3-hydroxyamino-2,3-dihydroimidazo[1,2-a]pyridine-2-ylidene)-2-(2-tienyl)acetonitrile as a new acid and base indicator in aquatic environments has been investigated. This compound has been synthesized by the reaction of 3-nitroimidazo [1,2-a] pyridine and 2-(2-thienyl) acetonitrile in a methanol solution by the hydrogen nucleophilic substitution. The aqueous-ethanol solution of this compound shows a change in color by adding acid and an base. For the potential function of this reagent as an indicator, the spectral properties of UV-Vis and the equilibrium of acid and base source have been examined. The results show that the reagent is an amphoteric with two stable ionization factors K_a and K_b with poor acid and base properties. Indicator dissociation constants in aqueous solutions specified by spectrophotometric method are pK_a = 9.73 and pK_b = 11.57. The types of base that can be titrated with this index have been reported. This index has been compared with effective acid and base indexes with similar pH range.

中文翻译：

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合成新型杂环染料化合物作为酸和碱反应的指示剂

在本研究中，使用2-（3-羟基氨基-2,3-二氢咪唑并[1,2- a ]吡啶-2-亚基）-2-（2-噻吩基）乙腈作为新的酸和碱指示剂水生环境已被调查。该化合物是通过3-硝基咪唑并[1,2- a ]吡啶和2-（2-噻吩基）乙腈在甲醇溶液中通过亲核氢取代反应合成的。通过加入酸和碱，该化合物的乙醇水溶液显示颜色变化。对于该试剂作为指示剂的潜在功能，已经检查了UV-Vis的光谱特性以及酸和碱源的平衡。结果表明，该试剂为两性离子，具有两个稳定的电离因子K _a和K_b具有较弱的酸和碱性质。通过分光光度法指定的水溶液中的指示剂解离常数为p K _a = 9.73和p K _b = 11.57。已经报道了可以用该指数滴定的碱的类型。该指数已与有效酸和碱指数相近的PH范围进行了比较。