Sodium picrate

Identification of Amines. Picric acid combines with many amines to give crystalline picrates, of general formula B,(NO )aCeHjOH, where B is a molecule of a monacidic base. These picrates have usually sharp melting- or decomposition-points, and serve to characterise the amines concerned. They may be formed either by (a) direct union of the acid and the base in a suitable solvent, or (6) by the interaction of sodium picrate and a salt of the amine in aqueous solution. 

If an ethanolic solution of picric acid is similarly added to one of aniline, no precipitation occurs, owing to the high solubility of aniline picrate in ethanol. If, however, a cold aqueous solution of aniline hydrochloride is added to a similar solution of sodium picrate and the mixture shaken, yellow crystals of aniline picrate, m.p. 165 , soon separate. 

Detection of Potassium in the presence of Sodium. Add a cold saturated aqueous solution of sodium picrate to a solution of potassium chloride. A rapid precipitation of the less soluble potassium picrate occurs, even from a i°o solution of potassium chloride. 

Dissolve a small quantity of the methiodide in cold water and add it with shaking to an excess of cold saturated aqueous sodium picrate solution. A yellow dovible salt of quinaldine niethoi icrate ami sodium picrafe. 

I or examples of other similar methopicriitcs uniting tvith picric acid or sodium picrate to livc "double piciatcs" ot larioiis stiibilifics, see b. (i. M inii... 

Procedure. Prepare a set of external standards containing 0.5 g/L to 3.0 g/L creatinine (in 5 mM H2SO4) using a stock solution of 10.00 g/L creatinine in 5 mM H2SO4. In addition, prepare a solution of 1.00 x 10 M sodium picrate. Pipet 25.00 mL of 0.20 M NaOH, adjusted to an ionic strength of 1.00 M using Na2S04, into a thermostated reaction cell at 25 °C. Add 0.500 mL of the 1.00 x 10 M picrate solution to the reaction cell. Suspend a picrate ion-selective electrode in the solution, and monitor the potential until it stabilizes. When the potential is stable, add 2.00 mL of a... 

It is not advisable to store large quantities of picrates for long periods, particularly when they are dry due to their potential EXPLOSIVE nature. The free base should be recovered as soon as possible. The picrate is suspended in an excess of 2N aqueous NaOH and warmed a little. Because of the limited solubility of sodium picrate, excess hot water must be added. Alternatively, because of the greater solubility of lithium picrate, aqueous 10% lithium hydroxide solution can be used. The solution is cooled, the amine is extracted with a suitable solvent such as diethyl ether or toluene, washed with 5N NaOH until the alkaline solution remains colourless, then with water, and the extract is dried with anhydrous sodium carbonate. The solvent is distilled off and the amine is fractionally distilled (under reduced pressure if necessary) or recrystallised. 

Note Sodium Picrate, Double Salts of. When an aq soln of Na picrate (3 moles) is stirred and heated with 3 moles of finely powdered Ba or Fb picrate, the resulting double salts are less sensitive to impact than the single salts (and for this reason are less dangerous to handle). The same can be said for other picrate double salts (Ref 4)... 

A large scale explosion involving initiation of wet sodium picrate by impact was investigated [1], A small sample heated to above 250°C exploded with sufficient violence to destroy the DTA thermocouple [2],... 

Favretto and co-workers [198,206-208] have described direct spectrophoto-metric methods for non-ionic surfactants based on the formation of a sodium picrate surfactant adduct. This method has been applied to seawater. A mean value of 93 1% was obtained in recovery experiments on C12E9 (at an aqueous concentration of 0.10 mg/1) extracted from synthetic sea water by means of this... 

Trimethyldecahydroquinolinium picrate, 3765 Ammonium picrate, 2322 Calcium picrate, 3430 Cobalt(II) picramate, 3460 Copper(II) picrate, 3432 Lanthanum picrate, 3741 Lead(II) picrate, 3436 Manganese picrate hydroxide, 3742 Mercury(II) picrate, 3433 S-7-Methylnonylthiouronium picrate, 3737 Nickel picrate, 3435 Potassium picrate, 2085 Sodium picrate, 2086 Zinc picrate, 3437... 

The liberation of hydrocyanic acid due to complete hydrolysis of cyano-genic glycosides can be determined by a simple colour test using sodium picrate paper (yellow), which turns red (sodium isopurpurate) in contact with HCN. 

Benzenediazonium Picrate(Diazobenzene Pi crate), C6Hs.N2.0.C6H2(N02)3 mw 333-22, N 21.02% yel crysts, mp- expl at 85° insol in w, eth or benz. Can be prepd by mixing aq solns of benzene-diazonium nitrate and sodium picrate. Other methods of prepn and props are described by Huisgen Horeld(Refs 2 3)... 

Dimethyl selenide, 28 grams, is added to 43 grams of benzyl bromide, the resulting brown mass dissolved in water, and the picrate precipitated by the aid of sodium picrate. The yield is about 38 grams, the product separating from alcohol in small needles, M.pt. 118° C. 

Tetryl is hydrolyzed rapidly by boiling aqueous sodium carbonate to form sodium picrate, sodium nitrite, and methylamine which escapes. It is not affected by prolonged boiling with dilute sulfuric acid. It reacts with aniline in benzene solution at ordinary temperature red crystals of 2,4,6-trinitrodiphenylamine, m.p. 179.5-180°, separate after the liquid has stood for a few hours, and extraction of the liquid with water yields an aqueous solution of methylnitramine. 

Sodium 2-nitrothiophenoxide, 2175 Sodium 4-nitrophenoxide, 2176 Sodium picrate, 2079... 

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