Pyrogallol and Tungstocilic Acid (TSA). I get a yellow color and was wondering what reaction is causing this.
Bearing in mind that pyrogallol is quite easily oxidised, it is possible that what you have observed is a reaction quite similar to that of tin (II) chloride reducing tungstates. If you look in Qualitative Inorganic Analysis by A. I. Vogel (my copy is the 4th edition hardcover page 574) the formula of the yellow colouration is given as W2O5, but this is very probably an oversimplification as both molybdenum and tungsten form polynuclear clusters in aqueous solution the identity of which varies greatly with pH.
Hope this helps.
Bearing in mind that pyrogallol is quite easily oxidised, it is possible that a reaction very similar to that of tin(II) chloride with tungstates has occured. If you look in Qualitative inorganic Analysis by A I Vogel (p574 in the hard back 4th edition) the formula of the yellow colouration is given as W2O5. This, though is probably an oversimplification as as oxoanions of tungsten and molybdenum have a tendency to form polynuclear clusters whose composition varies greatly with pH and concentration. Hope this helps
Sure it is a polynuclear tungstate. To make sure of that, add KHSO3 in NH3 0.1N, should turn blue.
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