Tropilium iodide

The fluoborate group can be displaced by the iodide ion to prepare tropilium iodide. You can see that the iodide ion is ionic by watching the reaction of the aqueous solution of this ion with silver ion. 

Tropilium iodide Tropilium fluoborate Triphenylmethane Cycloheptatriene Triphenylmethyl fluoborate... 

The tropilium fluoborate can be converted to tropilium iodide by dissolving the borate in the minimum amount of hot, but not boiling, water (a few drops) and adding to this solution 1.25 mL of a saturated solution of sodium iodide. Cool the mixture in ice, remove the solvent with a pipette, and wash the crystals with 2.5 mL of ice-cold methanol. Scrape most of the crystals onto a piece of filter paper and allow them to dry before determining the weight. To the crystalline residue in the test tube add a few drops of water warm the tube, if necessary, to dissolve the tropilium iodide and then add a drop of 2% aqueous silver nitrate solution and note the result. 

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See also in sourсe #XX -- [ ]

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