Alkaline picric acid

Some color reactions of D. g. are red with sodium nitroprusside in sodium hydroxide solution, orange with alkaline picric acid solution, and blue-violet with alkaline m-dinitrobenzene solution. D.g. are in-dispensible cardiotonic agents, used for long-term treatment of chronic heart weakness and defective heart valves. The pure glycosides are now used instead of leaf powders or extracts. 

Normal, fasting gastric juice reddens an alkaline picric acid solution after 10-16 minutes of heating. 

Table 1. Extraction (%) of alkali metal picrates from the aqueous into the organic phase by 3a-d 3a-d 10 2 M (in dichloromethane), alkaline metal picrates 10 1 M (in water), picric acid 7xl0 5 M (in water).

Cl Sulphur Black 1, which is produced from the relatively simple intermediate 2,4-dinitrophenol and aqueous sodium polysulphide. A similar product (Cl Sulphur Black 2) is obtained from a mixture of 2,4-dinitrophenol and either picric acid (6.148 X = N02) or picramic acid (6.148 X = NH2). A black dye possessing superior fastness to chlorine when on the fibre (Cl Sulphur Black 11) can be made from the naphthalene intermediate 6.149 by heating it in a solution of sodium polysulphide in butanol. An equivalent reaction using the carbazole intermediate 6.150 gives rise to the reddish blue Cl Vat Blue 43 (Hydron blue). This important compound, which also possesses superior fastness properties, is classified as a sulphurised vat dye because it is normally applied from an alkaline sodium dithionite bath. Interestingly, inclusion of copper(II) sulphate in the sulphurisation of intermediate 6.150 leads to the formation of the bluish black Cl Sulphur Black 4. 

The kinetics of the alkaline decompn of the subject compd was studied by Jones (Ref 3) Simkins Wright (Ref 4) prepd the compd by different methods and detd irs expl props, which are as follows 1) comparable to Tetryl in expl props 2) FI - 78% of Picric Acid 3) power by Trauzl test 136% of PA 4) Decomp w/o ignition at 205°, but ignites at once at 350° 5) decompd... 

Other drugs that change the color of the urine act as follows. Logwood (hematoxylon) does not color acid urine but produces a reddish or violet color in alkaline urine. Santonin imparts a yellowish color to acid urine, with a yellow foam if the urine is made alkaline, it imparts a very pronounced pink color. Picric acid gives reddish-brown color in both acid and alkaline urine. The various coal-tar products give a brownish-black color. Methylene blue imparts a green color. 

Since the estimated half-life has a maximum uncertainty factor of 3, the hydrolysis half-life at 20 °C and pH 6.8 may be as high as 900 days. The hydrolysis rate is expected to increase with increasing temperature and pH (Navy 1984b). Hydrolysis products include picrate ion, N-methylpicramide, methylnitramine, nitrite ion, and nitrate ion. In the dark and under buffered, alkaline conditions (pH 9), methylnitramine formation dominated (66%) picrate ion (28%), nitrite (4.1%), nitrate (3.1%), and N-methylpicramide (4.1%) were also formed. Under laboratory light and more acidic conditions (pH 4-6), N-methylpicramide (41%) and nitrate (35.2%) were the major products picrate ion (3.9%), nitrite (9.4%), and methylnitramine (0.01%) were also formed (Navy 1984b). In sea water at 25 °C and pH 8.1, 88% of initial tetryl hydrolyzed in 101 days, yielding picric acid as a hydrolysis product. This hydrolysis rate corresponds to a first-order half-life of 33 days (Hoffsommer and Rosen 1973 HSDB 1994). 

Based on effects observed in water (Navy 1984b), tetryl released to soil is expected to be susceptible to slow hydrolysis in acidic and neutral soils and to relatively rapid hydrolysis in highly alkaline soils (HSDB 1994). Samples of water collected from lysimeters containing tetryl-contaminated soil indicated that the major transformation products were picric acid (5-14%) and other polar, water- soluble decomposition products no tetryl was detected in the water, or in the soil at the end of the study, suggesting complete hydrolysis (Kayser and Burlinson 1988 Navy 1982). The specific reaction leading to these products was not determined. Because tetryl is subject to photolysis in water, it may be susceptible to photolysis on sunlit soil surfaces (HSDB 1994). 

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. 

Reagent. To a saturated solution of picric acid add sufficient sodium carbonate to make the solution strongly alkaline. 

The first example of the synthesis of a natural product by non-enzymic cyclization of a squalene derivative has been provided by Sharpless. Picric acid-induced cyclization of eryt/iro-18,19-dihydroxysqualene-2,3-oxide (18) resulted in the formation of a mixture of products from which ( )-malabaricanediol (19) could be isolated in 7% yield. The crythro-dihydroxysqualene oxide (18) was synthesized from squalene via the internal trans-oxide (20) and erythro-dio (21). The formation of the bromo-ether (22) permitted selective epoxidation of the other terminal double bond. Zinc dust reduction of (22) followed by mild alkaline... 

Attempts have been made to solve the problem by examining the rate of hydrolysis of the two D-glucose phenylhydrazones, and Frere-jacque/ who used oxalic acid and picric acid to remove the phenyl-hydrazine from the sphere of the reaction as an insoluble salt, claimed to show that both of the D-glucose a - and 9 -phenylhydrazones are derived from a-D-glucose on account of the downward trend of the mutarotation observed on making the solutions alkaline. This result is therefore not in conflict Avith the conclusions of Behrend. From similar studies StempeP concluded that "no information of value concerning... 

The reaction is carried out in alkaline solution (sodium or potassium hydroxide, or a mixture of the corresponding carbonates) so as to dissolve the nitro-compound and to neutralise the hydrochloric acid which otherwise impedes the chlorination of the picric acid. The reaction takes place very readily at a low temperature (between o and 5° C.). 

The bromide is prepared in the same way as the chloride, is insoluble in organic solvents, and melts at 251 C, It reacts "with alkaline sodium stannite solution, yielding a brick-red compound I., which turns brown on exposure to iightl This decomposition product when extracted with hot benzene gives II., the corresponding mercuric compound to I. It melts at 190° C., is insoluble in water, alkalies, dilute acids, or acetone, readily soluble in benzene or toluene, and is decomposed by concentrated liydrochloric acid. With mercuric chloride or picric acid it gives precipitates, but remains unchanged when boiled with potassium hydroxide, cyanide, or iodide. 

Yeast is the chief source of ribosenucleic acid, one of the simplest methods of isolation being that of Levene. It consists in adding, with grinding, an aqueous solution of potassium hydroxide to a thick paste of pressed yeast, till faintly alkaline to litmus saturated aqueous picric acid solution is now added and the mixture filtered. The filtrate contains nucleic acid, which is precipitated by adding hydrochloric acid. 

Measurement of creatinine in semm and urine is routinely performed by photometric methods such as the Jaffe reaction, which is widely accepted and involves the formation of an adduct of creatinine with picric acid in alkaline solution, whose absorbance is measured at 500 nm. However, this method is unspecific and subject to perturbation by many interfering substances from endogenous and exogenous origins. 

Vasitiades J. Reaction of alkaline sodium picrate with creatinine 1. Kinetics and mechanism of formation of the non creatinine picric acid complex. Clin Chem 1976 22 1664-71. 

The measurement of creatinine to assess renal function is fraught with technical problems. The reaction described by Jaffe in 1886, and which bears his name, is still widely used for the measurement of creatinine. The Jaffe reaction, however, despite its remarkable longevity, is notoriously nonspecific. The reaction involves the development of a red-colored complex between creatinine and picric acid in alkaline solution. Although the absorbance maximum for the creatinine-picrate... 

Glucose, heated with a dilute alkaline solution of picric acid, communicates to it a biood-red color. 

Incompot The vitamin is destroyed by alkalies and alkaline drugs such as phenobarbita] sodium and hy oxidizing and reducing agents. It is precipitated by tannins (which occur in wine) and by reagents which precipitate alkaloids, e.g. Mayer s reagent, mercuric chloride, picric acid, iodine. For stability in dry prepns Over several years see Partington, Waterhouse, J. Pharm. Pharmacol. 5, 715, 721 (1953). Chemical fate in alkaline solns Maier, Metzler, J. Am,... 

The non-enzymatlc determination of creatinine in urine and serum developed by van Staden [21] is based on Jaffa s reaction [22,23], which involves the formation of a red-orange compound on Interaction of the analyte with picric acid in an alkaline medium. The manifold used Is shown in Fig. 14.5. The sample —deproteinlzed serum to avoid the Interference from proteins or urine diluted to 1 100— Is placed on a sampler from which it Is Injected into the carrier and merged with a basic stream of picric acid. The indicator reaction takes place along a reactor submerged in a bath thermostated at 35 C, after which It reaches the detector flow-cell, where the absorbance Is monitored at 520 nm. The results obtained by this method are consistent with those found by the standard kinetic method [24,25]. The sampling frequency is 120 h 1. 

The most probable formula for dinitrostrycholcarboxylic acid is I, for alternative formulas with the carboxyl attached to the benzene nucleus are highly improbable in view of the simultaneous formation of picric acid and 3,5-dinitrobenzoic acid, and secondly because of the oxidation (alkaline permanganate) of strychnine to oxalylanthranilic acid (XI) (114). These other alternatives are definitely precluded by a consideration of the relation of strychnine to brucine and of the course of the degradation of the aromatic nucleus in derivatives of both these alkaloids. 

Analytical Characters.—(1.) With silver nitrate a dense, white-ppt. which is not dissolved on addition of HNOs to the liquid, but dissolves when separated and heated with concentrated. HNOs soluble in solutions of alkaline cyanids or hyposul-fites. (2.) Treated with NH4HS, evaporated to dryness, and. ferric chlorid added to the residue a blood-red color. (3.) With potash and then a mixture of ferrous and ferric sulfates a greenish ppt., which is partly dissolved with a deep blue color by HCl. (4.) Heated with a dilute solution of picric acid and then cooled a deep red color. (5.) Moisten a piece of filter paper with a freshly prepared alcoholic solution of guaiac dip the paper into a very dilute solution of CuSOi, and, after drying, into the liquid to be tested. In the presence of HCN it assumes a deep blue color. 

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. 

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