4-nitrobenzene-diazonium chloride, reagent

Nitrobenzene-diazonium chloride reagent the reagent (1) yields a red colouration (due to 2) with an ammonium salt in the presence of sodium hydroxide solution. 

Nitrobenzene-diazonium chloride reagent. Dissolve Ig 4-nitroaniline, N02 C6H4 NH2, in 25 ml 2m hydrochloric acid and dilute with water to 160 ml. Cool, add 20 ml of 5 per cent sodium nitrite solution and shake until the precipitate dissolves. The reagent becomes turbid on keeping but can be employed again after filtering. 

The spot-test technique is carried out as follows. Place a drop of the test solution in the tube of Fig. 11.56, add 1-2 drops 20 per cent sodium hydroxide solution and a few milligrams of Devarda s alloy. Place a watch glass with a drop of p-nitrobenzene-diazonium chloride reagent (for preparation, see under Ammonium, Section III.38, reaction 8) on its underside upon the funnel stopper. Heat the apparatus gently for a short time. Add a tiny fragment of calcium oxide to the drop of the reagent a red ring forms within 10-15 seconds. 

Ammonium, NH4 Sodium hydroxide Potassium tetraiodomercurate (Messier s reagent) Tannic acid-silver nitrate p-Nitrobenzene-diazonium chloride Evolution of ammonia gas upon heating Brown-yellow color or brown precipitate of mercury (II) amidoiodide high sensitivity all other metals (except Na and K) interfere Precipitate of black elemental silver, from neutral solution very sensitive Red-colored solution results in the presence of sodium hydroxide sensitivity, 0.7 pg of NH4+... 

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