Picric acid, 214 Table

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).

More recently, explosives have been tested for impact sensitivity by an impact machine in which 40 mg of explosive on sandpaper are placed between an anvil and a steel cylinder. A 2.5 kg weight is dropped from different heights and the sound produced serves to indicate a go or no go . The result from 25 drops is calculated to give a height at which the probability of explosion is 50%. Results from a compilation104 are presented in Table 12 and show that the relative values of TNT and picric acid are reversed from the previous table. TNT is relatively more sensitive on the Type 12 impact machine than in the FI impact test. TATB is so insensitive that it fails to explode at the maximum drop height of the machine. 

Picric acid and tetryl, both yellow powders, are no longer used by the military, though do-it-yourself books outline the synthesis of picric acid for the would-be criminal/terrorist and tetryl is still found in old munitions. Most of the military explosives are white-colored powders (TNT is cream colored). Since all, but TNT, decompose upon or instead of melting, they require some sort of compounding in order to be shapeable. They can be blended into TNT in a variety of ratios to make the formulations listed in Table 2.3. They can also be formulated in wax or plasticizer. The use of plasticizer is preferred because less dilution of the explosive occurs. (In the world of performance, TNT, with detonation velocity of 6900 m/s is considered a dilutant of HMX, detonation velocity of 9100 m/s.)... 

It is not customary to attempt the isolation of ketone or aldehyde intermediates (121) the formula serves merely as a reminder that once hydrolysis of the protecting enol ether or acetal occurs, the same type of structure is formed from any given dicarbonyl compound. Cyclization has been carried out in refluxing ethanolic picric acid or acetic anhydride with a few drops of sulfuric acid, but Hansen and Amstutz (63JOC393) offered excellent theoretical reasons for avoiding an excess of acid, and reported that best results (Table 3) can be obtained by refluxing the dry hydrobromide in acetic anhydride containing no sulfuric acid. 

Detonation pressures estimated by the simpler method are compared in Table VI with the corresponding ruby values for twenty-eight materials. Since we are at this point concerned only with reproducing ruby results, it is unimportant to the present discussion whether input heats of formation in the ruby computations are accurate although the AH/ for picric acid in Ref,... 

TNT mixtures with ammonium nitrate are more sensitive to impact than TNT itself. As shown by Hackel [49] (Table 49 and Fig. 70) mixtures containing 30-60% of ammonium nitrate are equally as sensitive as picric acid. Mixtures of this kind should not, therefore, be used for filling high initial velocity heavy calibre shells, e.g. armour-piercing shells. 

In addition to aluminium, calcium silicide or ferro-silicon, the use of silicon was also recommended. The comparative figures illustrating the effect of the addition of these compounds on the strength of the explosive have been given by Sar-torius [70] (Table 59). The power is expressed in terms of expansion in the lead block (taking picric acid as 100). 

If powder strips or tubes are laid along the axis of the bore the powder is much more difficult to detonate. A stronger initiator is required and not infrequently explosion occurs with a rate of about 1500 m/sec, instead of a detonation. The figures listed in Table 168 refer to the same conditions of initiation (20 g of picric acid) in a pipe 26/33 mm. 

In the case of picric acid (HPic), the solvation of Pic- in aprotic solvents is comparable to or slightly stronger than that in water (Table 2.7). Polarizable Pic- easily interacts with polarizable aprotic solvents by dispersion forces, while water does not interact as strongly with Pic- by hydrogen bonding because the negative charge of Pic- is delocalized. The pKa of picric acid is 0.38 in water, -1 in DMSO, and 11.0 in AN (Table 3.4). We can attribute most of the difference in pKa to the difference in the solvation of H+. 

Picric acid was used in grenade and mine fillings and had a tendency to form impact-sensitive metal salts (picrates) with the metal walls of the shells. The filling of mines and grenades was also a hazardous process, since relatively high temperatures were needed to melt the picric acid. Some of the properties of picric acid are presented in Table 2.9. 

RDX has a high chemical stability and great explosive power compared with TNT and picric acid. It is difficult to dissolve RDX in organic liquids but it can be recrystallized from acetone. It has a high melting point which makes it difficult to use in casting. However, when it is mixed with TNT, which has a low melting temperature, a pourable mixture can be obtained. Some of the properties of RDX are presented in Table 2.15. 

Table 5.14 The power index of some primary and secondary explosive substances taking picric acid as the standard...

ZhObshKhim 7, 2235-9 (1937) CA 32, 72 (1938)1Complex compds or Cu ammines with picric acid and some other nitrophenols such as [CufNHOj-tQHjCNCgjOla and [Cu(NH3)J [C6Hj(N0a)20]j Both compds seem to be explosive. They are not listed in our tables 20)H.Brinzinger and H.Plessing, ZAnorgChem 235, 110-14(1937) CA 32, 2450(1938)... 

Table 2 (Ref 23) gives the condensed phase products of the thermal decompn of Tetryl at 160°. Aside from undecompd Tetryl, Trinitro-anisole is the major product, although it tends to disappear on prolonged heating apparently forming Picric Acid, whose concn rises sharply at long decompn times. Note that the amount of condensed phase decreases on long heating. Consequently long heating favors production of gaseous decompn products...

Given the results in Table 2, indicating that scrubber charcoal had an impact sensitivity between picric acid and the commercial explosive, RDX, new procedures were adopted for the use and storage of scrubber charcoal ... 

The benzimidazoles form crystalline salts also when warmed with an equal weight of picric acid in aqueous ethanol.16 The melting points of the aldo-benzimidazole pierates (see Table I) thus furnish still another set of constants for characterization and identification purposes. 

On dissolution in hot water picryl chloride undergoes partial hydrolysis, picric acid being formed. Solubility data for picryl chloride in organic solvents are given in Table 104. 

Solubilty. Doliriski [41] gave the following figures for the solubility of picric acid in water at various temperatures (Table 109) (see also Findlay [41a]). 

The solubility of picric acid in sulphuric acid varies with the concentration of the latter. It is highest for concentrated acid and lowest in 18-20% acid. This can be seen from Table 110 [41b]. 

In organic solvents picric acid dissolves more readily than in water as Table 112 shows,... 

In Table 114 partition coefficient of picric acid between two liquid phases arc tabulated for water-toluene and water-ether (Sisley [44]). 

Similar values have been obtained by Sisley for amyl alcohol and water. Mindowicz [45] has also studied the partition coefficient (k) of picric acid between water and various organic solvents. Table 115 summarizes his results expressed in terms of the Nemst [46] and Shilov [47] equation... 

The rate of detonation of picric acid, as measured by various workers, is given in round numbers in Table 116. 

The following three grades of purity of picric acid are specified in the U S S R, standard, OST 3515 (Table 118). 

According to Medard [12], in the lead block test nitromethane gives figures similar to picric acid. T. Urbanski and Pawelec [35] found 325-360 cm3, averaging 345 cm3, i.e. 110% of that of picric acid. The same authors determined the lead block expansion when nitromethane was detonated by means of a No. 8 detonator Mid 1 or 5 g of tetiyl. The expansion given by tetryl was deducted from the bulk expansion (Table 126). 

No analytical methods specifically used for the determination of tetryl in biological fluids and tissues were located. One attempt to develop a method for detecting tetryl in animal tissues using high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection was unsuccessful because of suspected metabolism and binding of the parent compound and/or metabolites to macromolecules (Army 1981a). However, methods were located for the detection of the tetryl metabolites, picric acid and picramic acid, in urine and for the analysis of tetryl in hand swabs. Table 6-1 is a summary of methods used to determine tetryl metabolites in urine and tetryl in hand swabs. 

As the table shows, the amino substituents may contain two alkyl groups. Where Rj = H and R2 = C6H6, however, a product is obtained which is probably a 3,5-diimino-2,3-dithiacyclopentane (17).18 The basicity of this compound as compared with that of the tautomeric form (18) is so slight that protonation does not take place under the reaction conditions used, although a stable, sparingly soluble molecular compound is formed with picric acid. 

Technical Observations. Dinitrochlorobenzene is manufactured on a very large scale, and is used in the preparation of sulfur black T (q.v.) and other important dyes. It is, moreover, the starting material for a whole series of condensation products made by replacing the very labile chlorine atom by basic and other residues. Thus, it is easy to prepare dinitroaniline and dinitrophenol, as well as picric acid and dinitroanisole, from dinitrochlorobenzene. The accompanying formulas show only a small part of the reactions actually used (also see Table V). 

---