一种钴配合物的制备的实验中英

Experiment: the preparation of a cobalt (III) complexes

First, the purpose of the experiment

Master the most common method of preparation of metal complexes - substitution reaction and the oxidation-reduction reaction in the aqueous solution;

Second, the experimental principle

The use of the aqueous solution of the substitution reaction of preparation of metal complexes, is the reaction between a metal and a ligand in an aqueous solution. Actually is a suitable ligand to replace the water molecules in the hydrated complex ions. The oxidation-reduction reaction, the different oxidation states of the metal complex, it appropriate oxidation or reduction of the metal complexes in the presence of ligand.

Co (II) complexes can be quickly substituted reaction (activity), and Co (III) complexes of a substitution reaction is very slow (which is inert). Co (III) complex preparation process is generally by Co (II) (actually it is hydrated with a rapid response generated Co (II) complexes thereof), and between the ligand, then it oxidized to the corresponding Co (III) complexes (the coordination number is six).

The Common Co (III) complexes: [Co (NH3) 6] 3 + (yellow), [Co (NH3) 5H2O] 3 + (pink), [Co (NH3) 5Cl] 2 + (purple) , [Co (NH3) 4CO3] + (mauve), [Co (NH3) 3 (NO2) 3] (yellow), [Co (CN) 6] - (purple), [Co (NO2) 6] 3 + (yellow) and the like.

Third, laboratory supplies

Instruments and materials: electronic scales, beakers, Erlenmeyer flasks, graduated cylinders, mortar, funnel, iron sets, kerosene lamp, and a test tube (15 mL), dropper, medicine spoon, test tube holder, funnel stand, asbestos net, thermometer, filter paper, etc. .

Solid drugs: ammonium chloride, cobalt chloride,

Liquid medicines: concentrated ammonia, hydrochloric acid (6 mol / L, concentration) and H2O2 (30%).

Experimental

1 Preparation of Co (III) complexes

Conical flask, 1.0g of ammonium chloride was dissolved in 6 mL of concentrated aqueous ammonia, holding tapered bottleneck continuous oscillation to be completely dissolved, the solution was homogeneous. Fractional added 2.0g cobalt chloride powder plus side shake, plus after continue to shake the solution brown slurry. Further wherein the dropwise addition of hydrogen peroxide (30%) 2-3ml, plus side edge shaking, and then the addition was complete shaking When the solution stopped bubbling, 6 mL of concentrated hydrochloric acid was slowly added, plus side shaking, and alcohol lamp micro heat, can not be heated to boiling (the temperature should not exceed 85 ° C) by heating for 10-15 minutes while shaking side, then at room temperature the mixture was cooled and shaken until completely cooled, the precipitate filtered off. Precipitation scores washes with 5 mL of cold water, followed by cold 5 mL of 6 mol / L hydrochloric acid washing, product drying and weighing around 105 ℃.

Preview content

1, to make the high yield of the product prepared in this experiment, What steps do you think is more critical? Why?

2 Summary prepared Co (Ⅲ) complex chemical principles and the preparation of several steps.

实验:一种钴(III)配合物的制备

一、实验目的

掌握制备金属配合物的最常用的方法――水溶液中的取代反应和氧化还原反应；

二、实验原理

运用水溶液的取代反应来制取金属配合物，是在水溶液中的一种金属盐和一种配体之间的反应。实际上是用适当的配体来取代水合配离子中的水分子。氧化还原反应，是将不同氧化态的金属配合物，在配体存在下使其适当的氧化或还原制得金属配合物。

Co（II）的配合物能很快地进行取代反应（是活性的），而Co（III）配合物的取代反应则很慢（是惰性的）。Co（III）的配合物制备过程一般是，通过Co（II）（实际上是它的水合配合物）和配体之间的一种快速反应生成Co（II）的配合物，然后使它被氧化成为相应的Co（III）配合物（配位数均为六）。

常见的Co（III）配合物有：[Co(NH3)6]3+（黄色）、[Co(NH3)5H2O]3+（粉红色）、[Co(NH3)5Cl]2+（紫红色）、[Co(NH3)4CO3]+（紫红色）、[Co(NH3)3(NO2)3]（黄色）、[Co(CN)6]3-（紫色）、[Co(NO2)6]3+（黄色）等。

三、实验用品

仪器与材料：电子台秤、烧杯、锥形瓶、量筒、研钵、漏斗、铁架台、酒精灯、试管（15mL）、滴管、药勺、试管夹、漏斗架、石棉网、温度计、滤纸等。

固体药品：氯化铵、氯化钴、

液体药品：浓氨水、盐酸（6 mol/L、浓）、H2O2（30%）。

四、实验内容

1. 制备Co（III）配合物

在锥形瓶中将1.0g氯化铵溶于6 mL浓氨水中，待完全溶解后持锥形瓶颈不断振荡，使溶液均匀。分数次加入2.0g氯化钴粉末，边加边摇动，加完后继续摇动使溶液呈棕色稀浆。再往其中滴加过氧化氢（30%）2-3mL，边加边摇动，加完后再摇动，当溶液中停止起泡时，慢慢加入6 mL浓盐酸，边加边摇动，并在酒精灯上微热，不能加热至沸（温度不要超过85℃），边摇边加热10-15分钟，然后在室温下冷却混合物并摇动，待完全冷却后过滤出沉淀。用5 mL冷水分数次洗涤沉淀，接着用5 mL冷的6 mol/L盐酸洗涤，产物在105℃左右烘干并称量。

五、预习内容

1、要使本实验制备的产品的产率高，你认为哪些步骤是比较关键的？为什么？

2、总结制备Co（Ⅲ）配合物的化学原理及制备的几个步骤。

六、思考题

1、将氯化钴加入氯化铵与浓氨水的混合液中，可发生什么反应，生成何种配合物？

2、上述实验中加过氧化氢起何作用，如不用过氧化氢还可以用哪些物质，用这些物质有什么不好？上述实验中加浓盐酸的作用是什么？