Picric acid, potassium salt

Picric acid Potassium, metal Potassium permanganate Silver salts, organic Sodium, metal Sulfuric acid, concentrated... 

Picric acid added in small quantities to colors deepens them and increases their brilliancy without making them burn much faster. Stars containing picric acid ought not to be used in aerial shells, for they are likely to detonate either from the shock of setback or later from being ignited in a confined space. Mixtures which contain picric acid along with potassium chlorate or salts of heavy metals are liable to detonate from shock. 

For the qualitative determination of picric acid a characteristic reaction with potassium cyanide may be utilized. When an aqueous solution of the two compounds is boiled a red-coloured potassium salt of isopurpuric acid is formed. Formula I was assigned to this compound by Nietzki and Petri [54], while Borsche and Bocker [55] suggested the formulae Ha or lib. 

Trinitro-m-cresol may be separated from picric acid in the form of its potassium salt, taking advantage of a difference in the solubility of the potassium salts of the two compounds, as shown below ... 

A first requirement for a substance to produce a taste is that it be water soluble. The relationship between the chemical structure of a compound and its taste is more easily established than that between structure and smell. In general, all acid substances are sour. Sodium chloride and other salts are salty, but as constituent atoms get bigger, a bitter taste develops. Potassium bromide is both salty and bitter, and potassium iodide is predominantly bitter. Sweetness is a property of sugars and related compounds but also of lead acetate, beryllium salts, and many other substances such as the artificial sweeteners saccharin and cyclamate. Bitterness is exhibited by alkaloids such as quinine, picric acid, and heavy metal salts. 

Negative substituents enhance the acidic properties of phenols, an effect opposite to that produced with aromatic amines. o and p-Chloro-phenols are considerably stronger acids than phenol itself, and o- and p-nitrophenols are still stronger. Trinitrophenol, picric acid, is a strong acid whose salts are neutral and not decomposed by carbonic acid or by ammonium salts. These salts of picric acid can be salted out of neutral solutions by sodium or potassium chloride. With negatively substituted phenols, it may be possible to separate the phenolate from solutions which are neutral or weakly alkaline to litmus. In doubtful cases, just as with the amines, the precipitated material must be studied to determine whether it is the free phenol or one of its salts. The color of the precipitate gives an indication in the case of the nitrophenols, since the free phenols have only a weak yellow color, whereas the alkali salts are deep yellow. Solubility tests with indififerent solvents may be used in the case of uncolored compounds. Only the free phenol can be separated from acidic solutions. 

The potassium salt of this acid, which is also known as picro-cyaminic acid, is obtained by treating picric acid with solution of potassium cyanide. The ammonium salt obtained from the potassium salt by double decomposition with ammonium chloride was formerly used in dyeing under the name Grenat soluble. It produces reddish-brown shades on wool and silk, but has now entirely disappeared. 

Dr, Borlinetlo s Gunpowder. Mix very intimately 10 fjarts of Chili salt-] tre, 10 of picric acid, and 8J of potassium bichromate,... 

Trinitrocr sQi resembles picric acid in general, but melts at 107 and gives a readily soluble potassium salt. 

Perhaps the first of the numerous patents for mixtures of starch nitrate with oxidants, and the like, was assigned to W. Schiickher in 1889 for the production of a smokeless gunpowder. His mix included ammonium, barium, potassium, sodium and starch nitrates, together with potassium chlorate, picric acid salts, nitronaphthalene, and carbon. The starch nitrate used was probably defective in stability. 

Anhydrous potassium phenoxide was prepared by the method of Komblum and Lurie (47). Picryl chloride was prepared from picric acid by published procedures (48). DNBF (16) was prepared by nitration of benzofuroxan (49) and recrystallized from glacial acetic acid. The potassium salt of the methoxy adduct 17 was obtained from the reaction of methanolic DNBF with potassium hydroxide (50). PiDNBT (30) was prepared by cyclization of 2,2, 4,4, 6,6 -hexanitrohydrazobenzene (51) with concentrated sulfuric acid and recrystallized from glacial acetic acid yellow plates mp 291-294 °C (decomposition) NMR [100 MHz, (CH3)2SO-d6] 9.09 (d, 1 HJ = 1.9 Hz), 9.48 (s, 2 H), 9.45 (d, lH,/= 1.9 Hz). 

Incompatibility of all strychnine salts alkalies, alkali carbonates and bicarbonates, benzoates, dichromates, bromides, iodides, tannic and picric acids, salicylates, borax, gold chloride and other alkaloid precipitants, piperazine, potassium -mercuric iodide (riot if acacia is present). 

Analytical Characters.—(1.) Its intensely bitter taste. (3.) Its alcoholic solution, when shaken with a potassium salt, gives a yellow, crystalline ppt. (3.) An ammoniacal solution of cupric sulfate gives a green, crystalline ppt. (4.) Glucose, heated with a dilute alkaline solution of picric acid, communicates to it a blood-red color. (5.) Warmed with an alkaline solution of potassium cyanid, an intense red color is produced (the same effect is produced by ammonium sulfhydrate). (6.) Unbleached wool, immersed in boiling solution of picric acid, is dyed yellow. 

II. The albuminoids are precipitated in an insoluble form by 1, the concentrated mineral acids, notably HNOs 2, by potassium ferrocyanid in presence of acetic acid 3, by certain organic acids in the presence of cpncentrated solutions of NaCl or Na SO< 4, by tannin in acid solution 5, by phosphomolybdic or phospho-tungstic acid 0, by double lodid of potassium and mercury, or double iodid of potassium and bismuth, in acid solution 7, by solutions of the salts of Pb, Cu, Ag, Hg, U 8, by chloral, picric acid, phenol or trichloracetic acid. 

It is a strong acid, forming well crystallised yellow salts, which detonate violently when heated, some of them also by percussion. The potassium salt, C 6 H 2 (NO 2 ) 3 OK, crystallises in long needles very slightly soluble in water. The sodium, ammonium, and barium salts are, however, easily soluble in water. Picric acid, when heated, bums with a luminous and smoky flame, and may be burnt away in large quantity without explosion but the mere contact of certain metallic oxides, with picric acid, in the presence of heat, develops powerful explosives, which are capable of acting as detonators to an indefinite amount of the acid, wet or dry, which is within reach of their detonative influence. The formula of picric acid is... 

Potassium Picrate [KC 6 H 2 (N0 2 ) 3 0]. When a strong solution of picric acid is neutralised by carbonate of potash, this salt is thrown down in yellow crystalline needles, which require 260 parts of cold or 14 parts of hot water for their solution. In alcohol it is much less soluble. 

The active substance most often used in pyrotechnic whistles is gallic acid (3, 4, 5 trihydroxybenzoic acid). The potassium salts of benzoic acid of 2, 4, dinitrophenol and of picric acid (2, 4, 6 trinitro-phenol) and the sodium salt of salicylic acid (o-hydroxy benzoic acid) are also effective. They are combined with potassium chlorate, perchlorate, or nitrate (Formulas 156—160). 

For preparative purposes, purifications based on the precipitation of alkaloids are sometimes employed. A crude extract of the alkaloids is made with aqueous acid, subsequently the alkaloids are precipitated with reagents such as Mayer s reagent (IM mercury chloride in potassium iodide) or Reinecke s salt (5% ammonium reineckate in 30% acetic acid) at pH 2, or picric acid (saturated aqueous solution) at pH 5-6. After collection of the precipitate by filtration or centrifugation, the precipitate is dissolved in an organic solvent (acetone-methanol-water 6 2 1). The complexing group is then removed by means of an anion exchanger (Jordan and Scheuer 1965 Verpoorte and Baerheim Svendsen 1976). This method is particularly suited for the purification of quaternary alkaloids. 

---