Aryl 2,4-dinitrophenyl

Alkyl (or Aryl) 2 4-dinitrophenyl-sulphides (or thioethers) and the corresponding sulphones. Mercaptans react with 2 4-dinitrochlorobenzene in alkaline solution to yield crystalhne thioethers (2 4-dinitrophenyl-sulphides) (I) ... 

Aminolysis of a series of aryl 2,4-dinitrophenyl carbonates by a series of quinuclidines gave linear Br0nsted-type plots, the magnitudes of their slopes confirming their mechanisms as concerted.40 A comparison41 of the aminolysis, by primary amines, of 4-nitrophenyl phenyl carbonate (31 X = O) with its thiono analogue (31 X = S) is discussed in the section Thioacids, Thioesters, Thiolactones, and Thiocarbonates below. 

Dinitrobenzenesulfenyl chloride derivative (Aryl 2,4-dinitrophenyl sulfide)... 

General Method of Preparation of Alkyl (Aryl)2,4-Dinitrophenyl Sulfides... 

If the fV-aryl group is strongly activated, then it can be removed in nucleophilic substitution reactions in which the azole anion acts as leaving group. Thus l-t2,4-dinitrophenyl)pyrazole reacts with N2H4 or NaOMe. 

Aryl halides with a halogen activated by electron-withdrawing groups react with pyrrolidine enamines of cyclic ketones (68) to give the a-arylated ketones after hydrolysis. The enamine (28) with 2,4-dinitrochlorobenzene gave an excellent yield of 2(2,4-dinitrophenyl)cyclohexanone (88). The... 

The Zincke reaction is an overall amine exchange process that converts N- 2,A-dinitrophenyl)pyridinium salts (e.g, 1), known as Zincke salts, to iV-aryl or iV-alkyl pyridiniums 2 upon treatment with the appropriate aniline or alkyl amine. The Zincke salts are produced by reaction of pyridine or its derivatives with 2,4-dinitrochlorobenzene. This venerable reaction, first reported in 1904 and independently explored by Konig, proceeds via nucleophilic addition, ring opening, amine exchange, and electrocyclic reclosure, a sequence that also requires a series of proton transfers. By... 

Hydrolyses of p-nitrophenyl and 2,4-dinitrophenyl sulfate are accelerated fourfold and eightfold, respectively, by cycloheptaamylose at pH 9.98 and 50.3° (Congdon and Bender, 1972). These accelerations have been attributed to stabilization of the transition state by delocalization of charge in the activated complex and have been interpreted as evidence for the induction of strain into the substrates upon inclusion within the cycloheptaamylose cavity. Alternatively, accelerated rates of hydrolysis of aryl sulfates may be derived from a microsolvent effect. A comparison of the effect of cycloheptaamylose with the effect of mixed 2-propanol-water solvents may be of considerable value in distinguishing between these possibilities. 

The most commonplace substrates in energy-transfer analytical CL methods are aryl oxalates such as to(2,4,6-trichlorophenyl) oxalate (TCPO) and z s(2,4-dinitrophenyl) oxalate (DNPO), which are oxidized with hydrogen peroxide [7, 8], In this process, which is known as the peroxyoxalate-CL (PO-CL) reaction, the fluorophore analyte is a native or derivatized fluorescent organic substance such as a polynuclear aromatic hydrocarbon, dansylamino acid, carboxylic acid, phenothiazine, or catecholamines, for example. The mechanism of the reaction between aryl oxalates and hydrogen peroxide is believed to generate dioxetane-l,2-dione, which may itself decompose to yield an excited-state species. Its interaction with a suitable fluorophore results in energy transfer to the fluorophore, and the subsequent emission can be exploited to develop analytical CL-based determinations. 

The initial study of the La3 +-catalyzed methanolysis of carboxylate esters163 reported the apparent second-order rate constant for La2 + ( OCH3)2-catalyzed methanolysis of some representative examples of aryl esters (2, 5 and 2,4-dinitrophenyl acetate (14)), phenyl benzoate (15) and three aliphatic esters, ethyl acetate, isopropyl acetate (16) and tert-butyl acetate (17). Given in Table 6 are the rate constants for the La3+ and methoxide-catalyzed methanolysis of these esters along with... 

The Zincke reaction is an overall amine exchange process that converts N- 2,A-dinitrophenyl)pyridinium salts, known as Zincke salts, to A -aryl or A -alkyl pyridiniums upon treatment with the appropriate aniline or alkyl amine. 

Only highly activated aryl halides react with pyridines. Thus, 2,4-dinitrochlorobenzene with pyridine forms l-(2,4-dinitrophenyl)pyridinium chloride active heteroaryl halides such as 2-chloropyrimidine react similarly. To phenylate pyridine, diphenyliodonium ions are needed Ph2I+BF4 + pyridine —>> 1-phenylpyridinium BF4" + Phi. This reaction may involve initial electron transfer. 

With few exceptions the dianions of monoalkyl and monoaryl phosphates are unreactive but with a good leaving group, e.g. carboxylate, dianions undergo hydrolysis. The same reasoning applies to a dinitrophenoxide anion and the pH-rate profile for the hydrolyses of 2,4- and 2,6-dinitrophenyl phosphates differs from those of other aryl phosphates in that the dianion is more reactive than the monoanion species (Fig. 2)22-23. This reactivity is at-... 

The demonstration that the mechanism of catalysis may change to general base catalysis for weakly basic nucleophiles further complicates the interpretation of such plots. The most useful generalizations that can be extracted from the data for aryl acetates are illustrated in Fig. 18. This is a plot of data for the reactions of oxyanions with three esters, phenyl, 4-nitrophenyl, and 2,4-dinitrophenyl acetates under the same conditions. Only nucleophiles showing normal reactivity are included points for hydro, de ion and a-effect nucleophiles have been excluded. The data are those of Jencks and Gilchrist283, who published a slightly different version of this plot. 

The high reactivity of di- and trinitrophenyl fluorides towards nucleophiles has been used for the arylation of various N-nucleophiles. A method was developed for the determination of N-terminal amino acids in peptides. Thus, nucleophilic attack of the amino acid nitrogen at Sanger s reagent (2,4-dinitrophenyl fluoride, 4), hydrolysis and subsequent analysis of the N-(2,4-dinitrophenyl)amino acid allows determination of the amino acid.162,163 Although this method has been replaced by more efficient procedures, it marked a milestone in the elucidation of peptide structures (Nobel Prize 1958). A variety of N-nuclcophilcs (no amino acids) which have been used in the nucleophilic substitution of 2,4-dinitrophcnyl fluoride is listed. 

A wide range of organic azides such as alkyl,80 alkenyl,79,100 aryl, including dinitrophenyl and picryl,101-103 heterocyclic,28,91 trimethylsilyl,79,104 acyl,9 phosphoryl,105 sulfonyl,106 alkoxycarbonyl,9 and oxime azides107 has been found to add to norbornene,25,79,90,104,105,107-121 its derivatives,104 106,1 13,120,122-128 or to related bridged bicyclic... 

Formation of a symmetrical sulphide (a) (e.g. dipropyl sulphide, Expt 5.204), is conveniently effected by boiling an alkyl halide (the source of carbocations) with sodium sulphide in ethanolic solution. Mixed sulphides (b) are prepared by alkylation of a thiolate salt (a mercaptide) with an alkyl halide (cf. Williamson s ether synthesis, Section 5.6.2, p. 583). In the case of an alkyl aryl sulphide (R-S Ar) where the aromatic ring contains activating nitro groups (see Section 6.5.3, p. 900), the aryl halide is used with the alkyl thiolate salt. The alternative alkylation of a substituted thiophenol is described in Section 8.3.4, p. 1160. The former procedure is illustrated by the preparation of isobutyl 2,4-dinitrophenyl sulphide (Expt 5.205) from l-chloro-2,4-dinitrobenzene and 2-methylpropane-1-thiol. 

Asymmetric imidations of aryl alkyl sulfides with [(tosylimino)iodo]ben-zene, catalyzed by various chiral (salen)manganese(III) complexes, have been investigated in some detail [31,32]. The influence of catalyst structure, solvent, temperature, 3°-amine AT-oxides, and the presence of molecular sieves on product yields and the enantioselectivity of imidation with 17 was evaluated. Enan-tioselectivities as high as 90 % ee and 97 % ee with methyl 2-nitrophenyl sulfide and methyl 2,4-dinitrophenyl sulfide, respectively, were achieved. 

Kinetic data indicate that the hydrolysis of 5-2,4-dinitrophenyl 4,-hydroxythioben-zoate (61) in mild alkaline solutions (pH 8-11) most likely follows a dissociative, ElcB pathway, through a p-oxoketene intermediate, whereas at higher pH values an associative mechanism carries the reaction flux (Scheme 18). LFER relationships obtained from a kinetic study on the alkaline hydrolyses of substituted 5-aryl 4 -hydroxythiobenzoates seem to suggest that the associative pathway is a concerted, one-step process, rather than the classical mechanism via a tetrahedral intermediate.51... 

Aryl substituents at N2 tend to stabilize the 1-bromide center, and a range of poly-O-acetyl-a-D-glycosyl bromides with iV-benzoyl,112 N-tosyl,163-171 N-(2,4-dinitrophenyl),16S and other N-substituents168 have been prepared, all of which yield glycosides on treatment with alcohols. The N-benzoyl derivative (LXI) readily undergoes an intramolecular rearrangement112- 113 to give the oxazoline derivative hydrobromide (LXII), from which the free base (LXIII) can be prepared.113... 

Arylation of enamines234 represents an analogy of the Stork reaction.236 Reactive aryl halides usually cause C-arylation. Treatment of 2,4-dinitrochlorobenzene with 1 -pyrrolidino-1 -cyclohexene affords 2-(2,4-dinitrophenyl)cyclohexanone (64) in very good yield. As... 

However, neither copper(I) iodide nor photostimulation are absolutely necessary for the arylation of benzenetellurolate. Lithium benzenetellurolate and 1,2-bromoiodobenzene condensed in tetrahydrofuran at 20° to form 1,2-bis[phenyltelluro]benzene in 32% yield3. Sodium benzenetellurolate condensed similarly with l-chloro-2,4-dinitrobenzene at 20° in tetrahydrofuran/aqueous sodium hydroxide in the presence of a phase-transfer reagent. In this case 2,4-dinitrophenyl phenyl tellurium (m.p. 134°) was isolated in 30% yield4. Lithium methanetellurolate was arylated in tetrahydrofuran by iodobenzene5, 1,2-dibromobenzene, and l-bromo-2-methoxybenzene at 20°3. 

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