The residue is dissolved in alcohol and to the cold saturated solution a cold alcoholic solution of picric acid is added.
Picric Acid >>
We may also notice the conversion of picric acid.
With picric acid it forms a sparingly soluble picrate, which melts at 145 0 C. On the condition of phenanthrene in alcoholic solution see R.
The products of the action of nitric acid on cellulose are not nitro compounds in the sense that picric acid is, but are nitrates or nitric esters.
Shenstone, two classes are to be recognized: (I) Nataloins, which yield picric and oxalic acids with nitric acid, and do not give a red coloration with nitric acid; and (2) Barbaloins, which yield aloetic acid, C7H2N205, chrysammic acid, C 7 H 2 N 2 0 6, picric and oxalic acids with nitric acid, being reddened by this reagent.
Picric acid can also be obtained from it by first treating acetylene with sulphuric acid, converting the product into phenol by solution in potash and then treating the phenol with fuming nitric acid.
Hot concentrated nitric acid oxidizes it to picric acid and oxalic acid, whilst on treatment with hydrochloric acid and potassium chlorate it yields chloranil (tetrachloroquinone).
It forms a crystalline compound with picric acid.
Alkaline potassium ferricyanide oxidizes it to picric acid.
Picric acid forms many well-defined salts, of a yellow or red-brown colour.
The chief application of picric acid and its salts is in the manufacture of explosives.
When ignited, picric acid burns quietly with a smoky flame.
The more important picric powders are melinite, believed to be a mixture of fused picric acid and gun-cotton; lyddite, the British service explosive, and shimose, the Japanese powder, both supposed to be identical with the original melinite; Brugere's powder, a mixture of 54 parts of ammonium picrate and 45 parts of saltpetre; Designolle's powder, composed of potassium picrate, saltpetre and charcoal; and emmensite, invented by Stephen Emmens, of the United States.
Anschutz (Ber., 1884, 1 7, p. 439) estimates picric acid by precipitation with acridine.