Diphenylamine method

The DPA method is based on the colorimetric measurement of products formed by reaction of co-hydroxylevulinylaldehyde (from the deoxyribose released after depurination of DNA) with diphenylamine in 1 M perchloric acid.14-16 The reaction yields a mixture of products, such as that shown in Eq. 1.4,17 which together have an absorbance maximum at 595 nm. This method has a similar dynamic range to the DABA assay with colorimetric measurement. Interferences include proteins, lipids, saccharides, and RNA. 

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Jacque Stability Test. Jacque, director of the Spanish plant Cantabrica at Guldacano, near Bilbao, proposed a test for NC which was simple, rapid, and did not require complicated apparatus. It is not advisable to use this test when it is known in advance that the NC is of low stability Procedure. A NC sample of 2-3g, previously-dried in a loosely covered weighing dish or crystallizer to constant wt, is transferred to an oven maintained at 130—40° and left there for 2 hrs. It is cooled in a vacuum desiccator and reweighed. The sample is again heated at 140° and weighed at intervals of 2 hrs until it decomposes, as indicated by an abnormal loss of wt. After termination of the test, it is advisable to wash the NC with distilled water, add a few drops of 0. IN KMn04 soln and determine the amt of HN03, either by the nitron or diphenylamine method... 

The diphenylamine method can be scaled down to increase sensitivity and fluorescent methods are available using diaminobenzoic acid, diamidino-phenylindole (DAP1), ethidium bromide or propidium iodide (Kissane and Robins, 1958 Hinegardner, 1971 Klotz and Zimm, 1972) which are sensitive down to 0.1 fig DNA. 

Determine the amount of DNA attached to the filters by the diphenylamine method of Burton (10). 

A system for the screening and identification of reducing sugars in urine using one-dimensional t.l.c. on silica gel has been developed.Colour was developed by the aniline-diphenylamine method. 

Detailed colorimetric assay methods for nucleic acid derivatives will be confined to descriptions of slight modifications of three procedures diich have withstood well the test of time (f) the Mejbaum (76) modification of the Bial orcinol reaction for pentose (2) the Dische (42) diphenylamine method for desoxypentose and (S) the method of Fiske and Subbarow (45) for inorganic orthophosphate. Many other modifications of the original techniques have been advanced but, in our opinion, none offer a complete solution of such difficulties as may be encountered in nudmc acid studies. Discussions of the colorimetric techniques will be foimd in Schlenk s review (89), in the manual edited by Umbreit cf oZ. (61), and in the review by Dische (41). 

Dewar and his co-workers, as mentioned above, investigated the reactivities of a number of polycyclic aromatic compounds because such compounds could provide data especially suitable for comparison with theoretical predictions ( 7.2.3). This work was extended to include some compounds related to biphenyl. The results were obtained by successively compounding pairs of results from competitive nitrations to obtain a scale of reactivities relative to that of benzene. Because the compounds studied were very reactive, the concentrations of nitric acid used were relatively small, being o-i8 mol 1 in the comparison of benzene with naphthalene, 5 x io mol 1 when naphthalene and anthanthrene were compared, and 3 x io mol 1 in the experiments with diphenylamine and carbazole. The observed partial rate factors are collected in table 5.3. Use of the competitive method in these experiments makes them of little value as sources of information about the mechanisms of the substitutions which occurred this shortcoming is important because in the experiments fuming nitric acid was used, rather than nitric acid free of nitrous acid, and with the most reactive compounds this leads to a... 

Qualitative Analysis. Several quaUtative analyses can be employed. For example, in the oxamide method (59), oxaUc acid is first heated at approximately 200°C with concentrated aqueous ammonia in a sealed tube. When thiobarbituric acid is added and heated to 140°C, a condensed compound of red color forms. The analysis limit is 1.6 pg. In the diphenylamine blue method (59,60), oxaUc acid is heated with diphenylamine to form a blue color, aniline blue. The analysis limit is 5 pg. 

In the derivatization of sugars with aniline-diphenylamine reagent for example, this leads to unsatisfactory irregular coloration. The standard deviation for the method deteriorates from 2 to 3% to 5 to 8%. For this reason color reactions should be avoided for direct quantitation if it is possible to scan in the UV range without derivatization. 

This procedure is a modification of the method of Goldberg and Nimerovsky.1 Triphenylamine has also been prepared by the treatment of aniline or diphenylamine with potassium and then bromobenzene 2 and by the action of sodium on diphenylamine and bromobenzene.3... 

The green colour due to the Cr3+ ions formed by the reduction of potassium dichromate makes it impossible to ascertain the end-point of a dichromate titration by simple visual inspection of the solution and so a redox indicator must be employed which gives a strong and unmistakable colour change this procedure has rendered obsolete the external indicator method which was formerly widely used. Suitable indicators for use with dichromate titrations include AT-phenylanthranilic acid (0.1 per cent solution in 0.005M NaOH) and sodium diphenylamine sulphonate (0.2 per cent aqueous solution) the latter must be used in presence of phosphoric) V) acid. 

The other dibenzodiazepines were prepared by the PPA method as follows The diphenylamine derivative was heated with ten times its weight of PPA at 150-160 C for 3.5 h, the resulting solution was poured into ice-water, the mixture was made alkaline with coned NH, and the product was extracted with Et20. The extract was dried and evaporated in vacuo. 

The thin-layer technique (CA 60, 6691) utilizes aliquots of proplnt ether extract (I) and the ether soln (II) of a known mixt. II consists of nitrates of glycerol and glycol, di-Bu or di-Et phthalates, Et or Me centralites, DNT, and diphenylamine. The chromatoplates are made of 85 15 silica gel and plaster of Paris. These plates, containing spots of I and 11, are developed with 1 1 C6H6-petroleum ether, then sprayed with specific detectors by color. The method is much quicker and easier than chemical analysis and simpler than infrared spectroscopy and column chromatography... 

In an acetone extract from a neoprene/SBR hose compound, Lattimer et al. [92] distinguished dioctylph-thalate (m/z 390), di(r-octyl)diphenylamine (m/z 393), 1,3,5-tris(3,5-di-f-butyl-4-hydroxybenzyl)-isocyanurate m/z 783), hydrocarbon oil and a paraffin wax (numerous molecular ions in the m/z range of 200-500) by means of FD-MS. Since cross-linked rubbers are insoluble, more complex extraction procedures must be carried out (Chapter 2). The method of Dinsmore and Smith [257], or a modification thereof, is normally used. Mass spectrometry (and other analytical techniques) is then used to characterise the various rubber fractions. The mass-spectral identification of numerous antioxidants (hindered phenols and aromatic amines, e.g. phenyl-/ -naphthyl-amine, 6-dodecyl-2,2,4-trimethyl-l,2-dihydroquinoline, butylated bisphenol-A, HPPD, poly-TMDQ, di-(t-octyl)diphenylamine) in rubber extracts by means of direct probe EI-MS with programmed heating, has been reported [252]. The main problem reported consisted of the numerous ions arising from hydrocarbon oil in the recipe. In older work, mass spectrometry has been used to qualitatively identify volatile AOs in sheet samples of SBR and rubber-type vulcanisates after extraction of the polymer with acetone [51,246]. 

Ethyl amine was estimated by the method of Citron et al. [140], aniline by the method of Norwitz [141], diphenylamine by the method of DeAtley [142] and naphthyl amine by the method of Pandey et al. [143]. 

Many methods have been proposed and are used to study the thermal stability of propellants and to ensure the absence of possible autocatalysed decompositions during storage. None are sufficiently reliable to merit individual description. In practice, stabilisers are added, the usual being diphenylamine for nitrocellulose powders and symmetrical diethyl diphenyl urea (carbamate or centralite) for double base propellants. Provided a reasonable proportion of stabiliser remains, the propellant can be assumed to be free from the possibility of autocatalytic decomposition. The best test of stability is therefore a chemical determination of the stabiliser present. 

Most syntheses of naturally occurring phenazines, though, are based on a two-step elaboration of the central heterocycle of the phenazine [78]. The first key step involves the generation of orf/zo-monosubstituted 88 or orf/zo, ortho -disubstituted diphenylamines 89-91 via nucleophilic aromatic substitution. Ring formation is then achieved by means of reductive or oxidative cyclization, for which a number of efficient methods are available. The main flaw of this approach is the synthesis of the substituted diphenylamines via nucleophilic aromatic substitution, as this reaction often can only be performed under strongly basic reaction conditions and at high temperatures. In addition, the diphenylamines required may only be achieved with certain substitution patterns with high yields. 

The access to substituted diphenylamines has been significantly improved through the development of the Pd-catalyzed iV-arylation of anilines by Buch-wald and Hartwig. The cyclization of the substituted diphenylamines to give the corresponding phenazines may then be conducted according to standard methods [78]. 

Intramolecular cyclization of diphenylamines to carbazoles is one of the most versatile and practical methods. This has been achieved photochemically, thermally in the presence of elemental iodine at 350°C, or with platinum at 450-540°C, via free radicals with benzoyl peroxide in chloroform, or by using activated metals such as Raney nickel or palladium on charcoal. Most of these methods suffer from low to moderate yields, and, in some cases, harsh reaction conditions (8,480). 

Elemental composition K 28.22%, Cl 25.59%, and 0 46.19%. An aqueous solution is analyzed for potassium by AA, ICP, and other methods (see Potassium). Perchlorate ion may be analyzed by ion chromatography or a liquid-membrane electrode. Iodide, bromide, chlorate, and cyanide ions interfere in the electrode measurement. Alternatively, perchlorate ion may be measured by redox titration. Its solution in 0.5M H2SO4 is treated with a measured excess standard ferrous ammonium sulfate. The excess iron(II) solution is immediately titrated with a standard solution of potassium dichromate. Diphenylamine sulfuric acid may be used as an indicator to detect the end point ... 

The method that has been most utilized for the preparation of aromatic carbazoles from noncarbazole precursors is the dehydrogenation of a tricyclic indole, usually a 1,2,3,4-tetrahydrocarbazole. The synthesis of the latter s is outside the scope of this article. The next most used precursors are biphenyls with an ortho nitrogen substituent, and the next, diphenylamines the synthesis of these precursors is also not dealt with in detail here. Finally, a variety of approaches utilizing precursor indoles have been described some of these have been used only once, whereas others have been used often enough that they can be described as general. 

An efficient chemical process for closing a diphenylamine is that using palladium(II) acetate (2 mol for substrates carrying electron-withdrawing groups) in acetic acid-methanesulfonic acid. Carbazole formation has been achieved with alkyl-, halo-, nitro-, and carboxyl-substituted diphenylamines. 1-Chlorocarbazole and carbazol-l-yl carboxylic acid as examples were efficiently prepared. - This is probably the best method now available for cyclizing diphenylamines. 

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