Picryl chloride

Picryl chloride [88-88-0] M 226.3, m 83°. Crystd from CHCI3 or EtOH. 

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. 

A crystalline addition product of indole with picryl chloride (i.e. l-chloro-2,4,6-trinitrobenzene), together with an unidentified amorphous substance, were obtained by the action of picryl chloride on indole magnesium iodide, and analogous products were obtained in the reaction between the indole Grignard reagent and 1-chloro-2,4,5-trinitrobenzene. 

In hydroxyUc solvents, the reaction with aniline follows a bi-molecular course but is complicated by competing solvolysis. This is a striking result when compared with the behavior of picryl chloride, which is much more selective with regard to the same reagents (aniline and alcohol), and has been interpreted to mean that bond-breaking has made appreciable progress in the rate-determining step of the reaction of phosphonitrilic chloride. Furthermore, the same indication is obtained from the fact that in the reactions of the halides, the fluorine chlorine ratios are less than one. ... 

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). 

NONA was prepd in a mixed Ullman reaction using picryl chloride, 13 dichloro-2,4,6-trinitrobenzene and electrolytic Cu dust ... 

The picryls are usually prepd by reacting a picryl such as picryl chloride with an organic compd. Picryl peroxides and salts also exist. The entries below are picryl compds which can be considered expls, some of these such as Picryl Fluoride and Picrylpicryl Chloride have been used as expls... 

Activating agents, such as trifluoroacetic anhydride 1,1 -carbonyldiimidazolc carbodiimides sulfonyl, tosyl, and picryl chlorides and a range of phosphorus derivatives can promote direct solution reactions between dicarboxylic acids and diols or diphenols in mild conditions. The activating agents are consumed during the reaction and, therefore, do not act as catalysts. These so-called direct polycondensation or activation polycondensation reactions proceed via the in situ transformation of one of the reactants, generally the carboxylic acid, into a more... 

Step 1 of the SnAt mechanism has been studied for the reaction between picryl chloride (as well as other substrates) and OH ions (13-1), and spectral evidence has been reported for two intermediates, one a n complex (p. 679), and the other a radical ion-radical pair ... 

Epoxy-resins picryl chloride or chlor-2-4-dinitrobenzene p-phenyl diamine. Isocyanates proteolytic enzymes p henylene diamine complex salts of platinum cyanuric chloride. 

I-Chloro-2,4,6,-trinitrobenzene (picryl chloride) Trinitrobenzoic acid... 

The products of the reactions of picryl chloride with isomeric 4- and 5-aminobenzofurazans in dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) were studied by means of nonaqueous potentiometric titration. The effect of the position of the furazan fragment in 4- and 5-picrylaminobenzofurazans on the NH acidity is considered. The electron-acceptor properties of the furazan fragment were evaluated via inclusion of the resulting data into the pK -cr correlation for 2,4,6-trinitrodiphenylamines <2005RJC933>. 

Lasch-Loquire and coworkers [45] evaluated the contact hypersensitivity reaction against picryl chloride (0.5 mg/Kg Pb s.c.) in mice with Pb administered just before or during the sensitization period. Pb exposure suppressed the DTH response regardless of the window (before or during sensitization) in which it had been administered. 

In trinitrochlorobenzene (picryl-chloride) the chlorine is as mobile as in an acid chloride. 

There have, from time to time, been suggestions that electron transfer may mediate in processes which are formally ionic substitution reactions. Whilst such mechanisms have been established for a small number of systems (Kornblum, 1975 Bunnett, 1978), in other instances the evidence is less substantial. For example, dialkylaminyl spin adducts may be observed when secondary amines are allowed to react with picryl chloride in the presence of MNP (Bil kis and Shein, 1974). This can be interpreted in terms of Scheme 12, but alternatives involving nucleophilic addition to the trap merit consideration. 

The introduction of NO2 into the aniline molecule would be expected to reduce the nucleophilicity of NH2 and for / -N( >2 this should be more or less according to 0. Examples of this are not easy to find, but there are the necessary data for the reactions of picryl chloride with substituted anilines in methanol. Log k for the reaction of aniline itself is about —0.2 at 25 °C (extrapolated from measurements at much lower temperatures). For the reaction of p-nitroaniline log A is —4.06 p is about —3.4. These values give an apparent sigma value of 1.13 for p-NC>2 in this system, a little below the value for [Pg.512]

A recent study of the reactions of 2,4-dinitrochlorobenzene and of picryl chloride with a series of nucleophiles that are presented in Table 6 shows that a plot (not shown) of log k against the pK values of all the nucleophiles is badly scattered77. Differences of up to 108 are observed for bases with similar pKa values. Part of this scatter is due to deviations that result because different families of nucleophiles (with different nucleophilic atoms) give rise to different Br0nsted correlation lines. Thus, for the reactions of picryl chloride good correlations are observed for a family of oxyanions (ft = 0.38, plot not shown), primary and secondary amines (Figure 4, ft = 0.52) and quinuclidines (Figure 4, P = 0.66). 

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