Picryl chloride, preparation

Reactions specific to sym-trinitrobenzene Addition compounds Preparation of sym-trinitrobenzene Direct nitration of m-dinitrobenzene Preparation from a-trinitrotoluenc Preparation from picryl chloride Preparation from benzyl chloride Preparation from m-xylene Other preparatory reactions... 

Nakamura, Takagi and Ueno have also utilized 4 -nitrobenzo-l 5-crown-5 as a starting material Their goal was the formation of a colored crown which could be utilized in transport studies. They have prepared 4 -picrylaminobenzo-l 5-crown-5 for this purpose in the following way. 4 -Nitrobenzo-l 5-crown-5 was hydrogenated and then picryl chloride was added. Nucleophilic aromatic substitution apparently ensued (deep red color) and the product was th n isolated by standard techniques as a yellow solid (mp 155°, max 395 nm) in 72% yield as shown in Eq. (3.17). 

The action of hydroxylamine and sodium acetate in ethanol upon picryl chloride was stated to give 4,6-dinitrobenzofuroxan, and probably some of this compound was formed, although it was later shownthat much of the original work was faulty. A report that hydroxylamine and 2,4,5-trinitrotoluene give 5-methyl-6-nitro-benzofuroxan has been found to be incorrect. Benzofuroxan has not been prepared by V-oxidation of benzofurazan, and it seems unlikely that this could be achieved, since benzofuroxan itself is oxidizable by powerful reagents to o-dinitrobenzene (Section VI, B). A report of the oxidation by nitric acid of anthraceno[l,2-c]furazan to the furoxan is incorrectlv abstracted. 

The benzo analogue 684 of [1,2,4]triazino[3,2-6]thiazoles was prepared (88LA1089) by heating triazine derivative 632 with 2,4-dinitrochloroben-zene or picryl chloride in N,N-dimethyl formamide (Scheme 143). 

Trinitrochlorobenzene (picryl chloride) (87) can be prepared from the nitration of 2,4-dinitrochlorobenzene with nitronium tetrafluoroborate or mixed acid composed of fuming nitric acid and oleum. Picryl chloride is also synthesized from the reaction of phosphorous oxychloride with the pyridinium salt of picric acid. ... 

Many high explosives can be synthesized from the reaction of picryl chloride with various nucleophiles. 2,2, 4,4, 6,6 -Hexanitrodiphenylsulfide (10) can be prepared from the reaction of picryl chloride (87) with sodium thiosulfate in ethanol solution in the presence of magnesium carbonate. Oxidation of (10) with fuming nitric acid forms 2,2, 4,4, 6,6 -hexanitrodiphenylsulfone (88). ... 

The harsh conditions needed to introduce five or more nitro groups into diphenyl ether lead to the destruction of the aromatic ring. Highly nitrated derivatives of diphenyl ether can be prepared by an indirect route 2,2, 4,4, 6-pentanitrodiphenyl ether (92) is the product from the controlled nitration of (91), which is obtained from the reaction of picryl chloride (87) with sodium o-nitrophenolate. ... 

More complex explosives incorporating amino groups have been prepared from the reaction of polynitroarylene halides with amine nucleophiles. Agrawal and co-workers have synthesized PADNT (107) from the reaction of 4-amino-2,6-dinitrotoluene (46) with picryl chloride (87) in methanol 4-amino-2,6-dinitrotoluene is synthesized from the reduction of... 

Dinitrobenzofuroxan (DNBF) (68) has been prepared from the nitration of benzofuroxan (69) with mixed acid," and by treating picryl chloride (67) with sodium azide and heating the resulting picryl azide (70) in an inert solvent." " ... 

This is seen during the nitration of PATO (99), which on treatment with a mixture of nitric acid in acetic anhydride at 40 °C for 30 minutes yields the A-nitro product (106), whereas the same reaction at 60 °C for 1.5 hours yields the C-nitro product (107). An explosive known as PANT (109) has been prepared from the reaction of 4-amino-1,2,3-triazole (108) with picryl chloride followed by C-nitration of the 1,2,3-triazole ring with mixed acid at room temperature. ... 

The organic derivatives of hydrazoic acid which contain an aromatic ring with nitro groups comprise an important group of initiators. Picryl azide (VII), m.p. 89-90°C is a typical example. It has been prepared both by the action of nitrous acid on trinitrophenylhydrazine (Purgotti [154], Schrader [155] and Korczynski [156]) and by the action of sodium azide on picryl chloride. Rathsburg [157] suggested... 

The coupling of aryl halides with copper is called the Ullmann reaction.m The reaction is of broad scope and has been used to prepare many symmetrical and unsymmetrical biaryls.187 When a mixture of two different aryl halides is used, there are three possible products, but often only one is obtained. For example, picryl chloride and iodobenzene gave only 2,4,6-trinitrobiphenyl.188 The best leaving group is iodo, and the reaction is most often done on aryl iodides, but bromides, chlorides, and even thiocyanates have been used. 

The acid can be prepared from picryl chloride according to the method described by Golumbic, Fruton, and Bergmann,6 but the following modifications are recommended sodium metabisulfite should be used in place of sodium bisulfite the crude sodium salt is not recrystallized but is converted directly to the acid by the addition of hydrochloric acid to its acetone solution the product is recrystallized by dissolving it in a minimum amount of hot acetone, adding chloroform until crystallization starts, and cool- ing to about 0°. Two recrystallizations yield a product with m.p. 194-196°. 

The nitration of chlorobenzene is easier than the nitration of benzene and more difficult than the nitration of toluene. Trinitro-chlorobenzene (picryl chloride) can be prepared on the plant scale by the nitration of dinitrochlorobenzene, but the process is expensive of acid and leads to but few valuable explosives which cannot be procured more cheaply and more simply from dinitrochlorobenzene by other processes. Indeed, there are only two important explosives, namely TNB and hexanitrobiphenyl, for the preparation of which picryl chloride could be used advantageously if it were available in large amounts. In the laboratory, picryl chloride is best prepared by the action of phosphorus pentachloride on picric acid. 

Preparation of Trinitroanisol. Thirty-five grams of picryl chloride is dissolved in 400 cc. of methyl alcohol with warming under reflux, and the solution is allowed to cool to 30-35°. A solution of 23 grams of sodium hydroxide in 35 cc. of water is added slowly through the condenser, while the liquid is cooled, if need be, to prevent it from boiling. The mixture is allowed to stand for an hour or two. The red precipitate is filtered off, washed with alcohol, and stirred up with water while strong hydrochloric acid is added until all red color has disappeared. The slightly yellowish, almost white, precipitate, washed with water for the removal of sodium chloride, dried, and recrystallized from methyl alcohol, yields pale yellow leaflets of trinitroanisol, m.p. 67-68°. From anhydrous solvents the substance separates in crystals which are practically white. 

A 1,3-dipolar cycloaddition of indanoneenamines and nitrilimines produces the indeno[2,1 -cjpyrazole (52).135 The yields of such cyclization reactions are high (60-80%). Reactions of A-alkylpyridine-3-ylides with picryl chloride involving cyclization give a mixture of pseudoazulenes 35 and 36.103 An additional preparation of pyrindine 26 is from 1,2- and 1,4-oxides of azonine.55... 

Note. (1) To prepare picryl chloride, dissolve 5 g (0.022 mol) of picric acid in 50 ml of phosphoryl chloride and add dropwise with shaking 3.8 g (4.0 ml, 0.025 mol) of N,N-diethylaniline. Allow the resulting brown solution to remain at room temperature for 15 minutes and then pour it into 500 ml of iced water. Stir vigorously until the excess of phosphoryl chloride has hydrolysed and the product has solidified do not allow the temperature to rise above 35-40 °C during hydrolysis, cooling the mixture when necessary in an ice-salt bath. Filter off the almost colourless solid, wash it with cold water and dry it in a desiccator over calcium chloride. The yield of almost pure picryl chloride, m.p. 82 °C, is 5.0 g (92%). 

Preparation from picryl chloride. According to Ullmann and Bielecki [51] and also J. Meyer [52], trinitrobenzene may. be obtained by removing the chlorine atom from picryl chloride in the presence of copper ... 

Picryl chloride may be used as the starting material for the preparation of trinitrobenzene (p. 255). With strong reducing agents, picryl chloride yields triamino-benzene (Fleisch [31]) ... 

In 1912 Sprengstoff A. G. Carbonit [17] was granted a patent for a method of preparation of this explosive, consisting in reacting hexanitrodiphenyl sulphide with nitric acid. Since picryl chloride, as the starting material for picryl sulphide was rather expensive, another method of preparation of hexanitrodiphenyl sulphone, via tetranitrodiphenyl sulphide, was also used. The latter was obtained by treating chlorodinitrobenzene with sodium thiosulphate. Then it was nitrated and oxidized simultaneously with nitric acid to hexanitrodiphenyl sulphone ... 

The compound was first obtained by treating picryl chloride (Pisani [12]) or trinitroanisole with ammonia (Salkowski [13]). Later Witt and Witte [14] obtained it by the nitration of o- or p- nitroacetanilide in oleum solution. For the nitration a solution of KN03 in concentrated sulphuric acid was used. Spencer and Wright [15] applied Kym s method [lo] for the preparation of picramide, heating picric acid with urea at 173°C for 36 hr. The yield obtained was about 90% of the theoretical. 

Hexanitroazobenzene (m. p. 215-216°C) forms orange coloured needles. It was prepared by Grandmougin and Leeman [2] by acting with hydrazine on picryl chloride. In a more recent method chlorodinitrobenzene is reacted with hydrazine to yield tetranitrohydrazobenzene which is then further nitrated. Simultaneously the oxidation of the hydrazo to an azo group takes place ... 

Summary Picryl chloride is prepared by treating chlorobenzene with potassium nitrate and fuming sulfuric acid. The picryl chloride is then precipitated, washed with water, and then dried. The picryl chloride is then purified by recrystallization from an acetone/methanol mixture. Commercial Industrial Note Part or parts of this laboratory process may be protected by international, and/or commercial/industrial processes. Before using this process to legally manufacture the mentioned explosive, with intent to sell, consult any protected commercial or industrial processes related to, similar to, or additional to, the process discussed in this procedure. This process may be used to legally prepare the mentioned explosive for laboratory, educational, or research purposes. 

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