Picric acid, synthesis

Picric acid, synthesis of, 628 Pinacol rearrangement, 646 Pineapple, esters in, 808 Piperidine, molecular model of, 939 structure of. 918 P1TC, see Phenylisothiocyanate, 1031-1032... 

Uses Organic synthesis photographic agent manufacture of pesticides, herbicides, explosives, and wood preservatives yellow dyes preparation of picric acid and diaminophenol (photographic developer) indicator analytical reagent for potassium and ammonium ions insecticide. 

The presence of three nitro groups on the aromatic ring of picryl chloride makes the chloro group extremely reactive towards nucleophiles. Picryl chloride (87) is hydrolyzed to picric acid (4) in the presence of hot water or aqueous sodium hydroxide. Aminolysis of picryl chloride in the presence of primary and secondary amines is complete in minutes at room temperature. Picryl chloride is therefore a very useful starting material for the synthesis of a range of other picryl derivatives. The reaction of picryl chloride (87) with ammonia can be used to synthesize 2,4,6-trinitroaniline (53) (picramide). Treatment of picryl chloride with alcohols under reflux forms picric acid and the alkyl chloride of the corresponding alcohol, whereas the same reaction in the presence of alkali metal hydroxides, or the alkoxide anion of... 

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.)... 

Indolizidine has been made in 68% yield by the action of silver ions on JV-chloroazacyclononane in dioxane.231 Pyrrolizidine and quinolizi-dine have been prepared similarly but in much poorer yields. Also, 1-methyl-5-hydroxyazacyclononane gave a trans-iustd quaternary salt (172) when heated with either perchloric, hydriodic, or picric acid in ethanol.232 However, it is more usual to apply this reaction in the reverse direction for synthesis of medium ring compounds. 

S.G.P = denomination of-" permitted explosives in Belgium S-FI-process (RDX-synthesis) 68 shaped charge 42 67 283 sheathed explosives 284 shelf life (storage life) 114 285 Shellite (UK) = Tridite (USA) = mixtures of picric acid and hexanitrodi-phenylamide... 

The progress in the development of improved monitoring techniques for the heterogeneous synthetic reactions involved in the solid phase method provided the feedback control which was necessary for the full automation of the peptide synthesizers. A monitoring system, which is based on the titration of the unreacted polymer-peptide chains with picric acid 34,35), on coupling with a peptide synthesizer provided an automatic feedback 36). This feedback is to implement the next step in the synthesis if the level of the unreacted peptide chains is below the acceptable preset value, or otherwise to repeat the last step. 

Phthalimide, 2, 75 7, 8, 78 Phthalimide synthesis, 7, 78 Phthalimido Malonic Ester, 7,78 Picric acid, 4,16... 

Picric acid was another explosive used in the war and from 1917 to 1919, Ruth King28 was assigned as a Wartime Research Worker at Chiswick Laboratory, Department of Explosive Supply, Ministry of Munitions, to research the optimum conditions for its synthesis. 

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... 

Dinitrophenol (commercial mixture of the 2,3- and 2,6- isomers, but mostly the 2,4- isomer) is used in the synthesis of dyes, picric acid, picramic acid, wood preservatives, diaminophenol dihydrochloride (a photographic developer), explosives, and insecticides, and as a pH indicator. 

Controlled-potential coulometry also offers possibilities for the electrolytic determination (and synthesis) of organic compounds. For example, trichloroacetic acid and picric acid are quantitatively reduced at a mercury cathode whose potential is suitably controlled ... 

Chemistry Chloropicrin s first reported preparation, by the Scottish scientist John Stenhouse, was in 1848 and involved the reaction of a chlorinating agent (bleaching powder) with picric acid (iym-trinitrophenol). It is this synthesis that led to the name chloropicrin, even though the ring present in picric acid is absent in the product chloropicrin. 

In 1865 just prior to Kekule s synthesis of phenol, Joseph Lister (1827-1912) was experimenting with carbolic acid as an aid to antiseptic surgery which he had pioneered. A mixture of crystallised carbolic acid and shellac (lac plaster) was employed in the finally adopted mode of application. The requirement of phenol for the manufacture of picric acid during the Boer war and other uses resulted in a demand which soon outstripped the resources of phenol/cresols available from coal distillation. Synthetic phenol thus became a potentially important intermediate. The lengthy processing involved in the separation of phenol and the isomeric cresols led to the desirability for specific syntheses. In 1978 of the world production of phenol only 3% came from coal sources by extraction of the mixed phenols (about 1.5% in coal tar) with 10% sodium hydroxide, acidification with carbon dbxide and separation. Phenolic compounds are also formed during catalytic cracking processes in the petroleum industry. There are historically six industriai processes for the production of synthetic phenol, variously from benzene and toluene, some of which are also applicable to the cresols and the dihydric phenols. 

Synthesis of the previously unreported W(tbq)4 chelate initially involved a Schraup synthesis of Htbq. Previous attempts in other laboratories had failed because of the acid cleavage of the tert-hutyl group in the arsenic acid oxidation step (16). We have successfully used picric acid and 4-tgrt-butyl-2-nitrophenol as oxidants with yields of 5-10%. The procedure is similar to that used for Hmq (3,6). The W(tbq)4 chelate was prepared by the decarbonylation of W(CO)e in mesitylene heated under reflux, followed by sublimation of unreacted material and crystallization from chloroform. Chromatographic separation on silica gel with 1 1 v/v CHCI3 hexane produced an analytically pure W(tbq)4 chelate. 

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