Ethers picryl

Addition of methanol to the reaction of aniline with picryl ether in benzene resulted in a continuous curvilinear increase of k over the entire range of solvent composition from pure benzene to pure methanol155. The order in aniline changes from three in benzene to... 

Phenol ethers, like the parent phenols, are reactive substrates. Phenol ethers like anisole and phenetole are readily nitrated to their picryl ethers, 2,4,6-trinitroanisole and 2,4,6-trinitrophenetole respectively, on treatment with mixed acid composed of concentrated nitric and sulfuric acids at 0 °C. Such reactions are vigorous, prone to oxidative side-reactions, and pose a considerable safety risk. The direct nitration of 2,4-dinitrophenol ethers, obtained from the reaction of 2,4-dinitrochlorobenzene with alkoxides, provides a more practical route to picryl ethers on an industrial scale. ... 

The observation that picryl ethers of oximes (106) rearrange without a catalyst established that the role of the catalyst was to convert the hydroxyl... 

Felix, G. and Bertrand, C., HPLC on n-propyl picryl ether silica gel, J. High Resolut. Chromatogr. Chromatogr. Commun., 1, 714, 1984. 

The spectral data for a variety of 1 1 and 1 2 adducts are collected in Table 2. As with the adducts from picryl ethers the visible spectra of 1 1 adducts from trinitrobenzene show two visible maxima whereas the 1 2 adducts have a single rather broad visible absorption. The NMR spectra of the 1 1 adducts show, typically, two bands due to ring protons, often exhibiting spin-spin coupling, at c. —8 4 (relative intensity 2) and — 6-0 p.p.m. (relative intensity 1). The position of the low-field band shows little dependence on the nature of the added group,... 

Picramide and its N-substituted derivatives introduce the added complication that proton loss may occur from the amino-group to give the Bronsted bases 23 (R = H, alkyl, phenyl). Green and Rowe (1913) found support for this formula from the alkali metal analyses of the solids formed from many polynitroanilines with bases. In fact picramide itself has been frequently used as an indicator for establishing H-acidity scales in basic media on the assumption that its indicator behaviour is due to proton loss (Schaal, 1955 Stewart and O Donnell, 1962 Stewart et al., 1962). The most likely other alternatives for the products of 1 1 interaction of picramides with bases are 24 and 25 (R = H, alkyl, phenyl R =R = H, alkyl). Formula 24, the analogue of Meisenheimer s formula for the adducts of picryl ethers, was suggested by Busch and... 

CA 49, 2300(1955)(Reacts with picric acid to give Et picryl ether and picryl acetate)... 

When base was added to a solution of N-methyl-N-/l-hydroxyethyl picramide 20 in a polar solvent, the isolable cyclic Meisenheimer complex 21 was formed (Scheme 8). At pH > 12 the conversion is virtually complete. Rapid protonation of 21 causes quantitative formation of picryl ether 22 trapped as an ammonium ion. The corresponding free base was unstable and tended to rearrange in the opposite direction [17]. 

Alkylation of polyhydric phenols such as resorcinol, hydroxyhydroquinone, orcinol, and pyrogallol with an alkyl iodide and alkali gives nuclear alkylation products as well as aryl ethers.760 In this reaction phioroglucinol gives hexa-methyl-l,3,5-cyclohexanetrione but there is a 65% yield of the 0-alkylation product 1,3,5-trimethoxybenzene if the mixture is kept acid during the alkylation.761 Philbrook and Massey762 report the preparation of picryl ethers from silver picrate and alkyl halides. 

Although this type of structure was first reported by Jackson et al. in 1900 for the reaction between picryl ether and potassium alkoxide, it was Meisenheimer who actually isolated and characterized the structure of such molecule for the first time in 1902. Since then, the stable or transient anionic a complexes formed from electron-deficient aromatic compounds and a variety of organic and inorganic bases" are generally called the Meisenheimer complexes. Occasionally, this type of molecule is also referred to as the Meisenheimer adducts, Meisenheimer compounds, Meisenheimer cr-adducts, Meisenheimer a complexes, Jackson-Meisenheimer adducts, or Jackson-Meisenheimer complexes. ... 

Basicity tests in analysis 87 Beckmann rearrangement 623-628 of 0-picryl ethers 624... 

H,iBrN407, p-Bromobenzophenone oxime 0-picryl ether (anti form), 38B, 151... 

Heterogeneous derivatizations, either in thepre- or postcolumn mode, using a reagent as a solid or bonded to packing particles have been explored by Krull and co-workers. Alkyl iodides and epoxides were converted to picryl ethers using silica supported silver picrate before HPLC separation. UV detectability at 220 nm was markedly improved with detection limits at the ppb level. Lower detectability was possible using either reductive or photolysis electrochemical detection. 

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