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.