Of p-nitroaniline

Prepare the diazoniuni fluoborate from 34 g. of p-nitroaniline as detailed in Section IV,68 for o-Nitroaniline. 

Dissolve 10 g. of p-nitroaniline (Section IV,51) in a mixture of 21 ml. of concentrated hydrochloric acid and an equal volume of water, and cool rapidly to 0° in order to obtain the hydrochloride of the base in a fine state of division. Diazotise in the usual way (see Section IV,68) by the gradual addition of a solution of 6 0 g. of sodium nitrite in 12 ml. of water. Continue the stirring for a few minutes, filter the solution rapidly, and add it from a separatory funnel to an ice-cold solution of 41 g. of sodium sulphite (90 per cent. NajS03,7H20) in 100 ml. of water containing... 

At lower acidities the observed rate constant for nitration of p-nitroaniline becomes greater than that for nitration of anilinium. ... 

The diffusion, location and interactions of guests in zeolite frameworks has been studied by in-situ Raman spectroscopy and Raman microscopy. For example, the location and orientation of crown ethers used as templates in the synthesis of faujasite polymorphs has been studied in the framework they helped to form [4.297]. Polarized Raman spectra of p-nitroaniline molecules adsorbed in the channels of AIPO4-5 molecular sieves revealed their physical state and orientation - molecules within the channels formed either a phase of head-to-tail chains similar to that in the solid crystalline substance, with a characteristic 0J3 band at 1282 cm , or a second phase, which is characterized by a similarly strong band around 1295 cm . This second phase consisted of weakly interacting molecules in a pseudo-quinonoid state similar to that of molten p-nitroaniline [4.298]. 

FIGURE 3 Release of -nitroaniline and the degradation of PCPA versus time. Disks (1.4 cm in diameter and 1 mm thick) of poly-(carboxyphenoxyacetic acid) (PCPA) were prepared containing 5% (w/w) -nitroaniline by compression molding, and degraded in 0.1 M pH 7.4 phosphate buffer at 37°C. The cumulative release of p-nitroaniline and degradation of PCPA were measured by absorbance at 380 and 235 nm, respectively. 

The acidity function is determined by successive use of a range of indicators. Hammett and Deyrup started with p-nitroaniline, the pKAl of which in a dilute aqueous solution is 1.11 (the solvolysis constant has been identified with the acidity constant). Since in a dilute aqueous solution, Yb = Ybh+ 1, the acidity function for the aqueous media goes over to the PH scale. By means of p-nitroaniline, the acidity constant of another somewhat more acidic indicator is obtained under conditions such that both forms of each indicator are present at measurable concentrations. Then H0 as well as the p A2 of the other indicator is determined by using Eq. (1.4.40). By means of this indicator, values of H0 not accessible with p-nitroaniline may be reached. The H0 scale is further extended by using a third indicator and its p A, is determined in the same way (see Fig. 1.11). The concentration ratios are determined photometrically in the visual or ultraviolet region. Figure 1.12 shows the dependence of H0 on the composition of the H2S04-H20 mixture and was obtained as indicated above. 

Li Y.S., Vo-Dinh T., Stokes D.L., Yu W., Surface-enhanced Raman analysis of p-nitroaniline on vacuum evaporation and chemically deposited silver-coated alumina substrates,Appl. Spectrosc 1992 46 1354-1357. 

Two commercial disazo disperse dyes of relatively simple structure were selected for a recent study of photolytic mechanisms [180]. Both dyes were found to undergo photoisomerism in dimethyl phthalate solution and in films cast from a mixture of dye and cellulose acetate. Light-induced isomerisation did not occur in polyester film dyed with the two products, however. The prolonged irradiation of Cl Disperse Yellow 23 (3.161 X = Y = H) either in solution or in the polymer matrix yielded azobenzene and various monosubstituted azobenzenes. Under similar conditions the important derivative Orange 29 (3.161 X = N02, Y = OCH3) was degraded to a mixture of p-nitroaniline and partially reduced disubstituted azobenzenes. 

In general, metal complexes formed from bidentate azo chromogens are little used as dyes but do find important applications as pigments (section 2.3.2). Rare exceptions exist, however, such as the nickel(II) complex of p-nitroaniline— BON acid (5.11). This has been used for bordeaux prints of high light fastness on cotton fabrics. Two possible modes of bidentate attachment to the nickel atom can be envisaged (Scheme 5.2). 

The classical idea of through-conjugation is revised the importance of structures 52 and 53 was criticized in particular by Hiberty and Ohanessian159. There is a tendency to explain physical and chemical properties of derivatives of p-nitroaniline without considering quinonoid structures like 52 to be the most important ones. 

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]

National Toxicology Program Toxicology 2Md carcinogenesis studies of p-nitroaniline (CAS No. 100-01-6) in B6C3FI Mice (Gavage Studies). Technical Report Series 418, NIH Pub No 93-3149, pp 1-206. US Department of Health and Human Services, Public Health Service, National Institutes of Health, 1993... 

Auramine 14, Red of p-Nitroaniline 23, KC103 25, MgC03 4 lattosio (milk sugar) 14%... 

The influence of the structure of the main chain on the chymotrypsin catalyzed release of p-nitroaniline is shown in Fig. 15. Oligopeptide p-nitroanili-des were attached to HPMA copolymers (as side-chains) and to polyethylene glycol (end-point attachment). From the values of kcat/KM it is evident that all oligopeptide p-nitroanilides attached to PEG were cleaved faster than those attached to HPMA copolymers. It appeared that the PEG substrates fit better into the active site of chymotrypsin due to the linearity and flexibility of the PEG molecule, and the type of spacer attachments [255]. 

Fig. IS. The influence of the structure of the main chain on the chymotrypsin catalyzed release of p-nitroaniline. The cleaved bond is denoted by an arrow. Data from [255]...

FIGURE S.4 Relative fibrin-clotting and amidolytic activity of thrombin as a function of the concentration of desalted fermented anchovy sauce (dFAS). Anticoagulation activity was assessed by the increase in the fibrin clotting time (empty circles) and the release of p-nitroaniline (closed circles). Data are presented as the mean SD (n —3). Source Kim et at. (2004). Permission has been obtained for the use of copyrighted material from Elsevier B.V. 

Heat a mixture of 15 g. of p-nitroacetanilide and 75 ml. of 70 per cent, sulphuric acid (1) under a reflux water condenser for 20-30 minutes or until a test sample remains clear upon dilution with 2-3 times its volume of water. The p-nitroaniline is now present in the liquid as the sulphate. Pour the clear hot solution into 500 ml. of cold water and precipitate the p-nitroaniline by adding excess of 10 per cent, sodium hydroxide solution or of concentrated ammonia solution. When cold (cool the mixture in ice water, if necessary), filter the yellow crystalline precipitate at the pump, wash it well with water, and drain thoroughly. Recrystallise it from a mixture of equal volumes of rectified (or methylated) spirit and water or from hot water. Filter, wash and dry. The yield of p-nitroaniline, m.p. 148°, is 11 g. 

With two equivalents of p-nitroaniline, selenium is set free, and 1-p-nitroanilinoacetylacetone,... 

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