2-[2′-(6-甲氧基-苯并噻唑)-偶氮]-1,8-二羟基萘-3,6-二磺酸的合成及其与钛的显色反应

Synthesis of 2[2′(6 Methoxy benzothiazolyl)azo]1,8 dihydroxynaphthalene 3,6 disulfonic Acid and Its Color Reaction with Titanium

合成了新的杂环偶氮变色酸类试剂———２［２′（６甲氧基苯并噻唑）偶氮］１，８二羟基萘３，６二磺酸，并系统探讨了在ｐＨ４．５的邻苯二甲酸氢钾ＮａＯＨ介质中显色试剂与钛的显色反应特性。结果表明，在溴化十六烷基吡啶存在下，试剂与Ｔｉ（Ⅳ）形成２∶１的络合物，显色反应１５ｍｉｎ完全并至少稳定４ｈ，最大吸收波长为６７０ｎｍ，表观摩尔吸光系数达１．６７×１０５Ｌ·ｍｏｌ－１·ｃｍ－１，钛的质量浓度在０～４００μｇ／Ｌ时符合比尔定律。用拟定的方法测定了硅砖等标准物质中的Ｔｉ（Ⅳ），所得结果与标准值的相对误差均小于４％，ＲＳＤ（ｎ＝５）小于３．５％。

The synthesis of 2 [2′ (6 methoxy benzothiazolyl) azo] 1,8 dihydroxynaphthalene 3,6 disulfonic acid (CH 3O BTCA) and its color reaction with titanium were studied spectrophotometrically. In the presence of CPB, titanium reacts with CH 3O BTCA to form a stable complex in a C 6H 4(COOK)COOH NaOH buffer solution at pH 4.2～4.8. The ratio of n Ti(Ⅳ) ∶ n CH 3O BTCA in the complex is found to be 1∶2. The chromogenic reaction completes within 15 mins and is stable for at least 4 h. The apparent molar absorptivity is 1.67×10 5 L·mol -1 ·cm -1 at 670 nm. Beer's law is obeyed in concentration range of 0～400 μg/L for titanium. The method is highly sensitive and selective and has been used for rapid determination of Ti(Ⅳ) in standard silicon brick reference materials. The relative errors of the results provided by this method are less than 4% with precision of less than 3.5% RSD( n =5).