For aniline

Note. All but the purest samples of monomethylaniline contain sufficient aniline to give positive (although possibly weak) reactions to certain tests for aniline (particularly Tests i and 4). If it is suspected that aniline is present solely as an impurity, the positive tests for monomethylaniline (particularly Test 4 below) should be applied. 

The diarylurea is insoluble in boiling water and is therefore easily separated from the monoarylurea, which is readily soluble. The proportion of diarylurea is highest for aniline and decreases with substituted anilines. 

Gassman and co-workers developed a synthetic route from anilines to indoles and oxindoles which involves [2.3]-sigmatropic rearrangement of anilinosul-fonium ylides. These can be prepared from Ai-chloroanilines and ot-thiomcthyl-ketones or from an aniline and a chlorosulfonium salt[l]. The latter sequence is preferable for anilines with ER substituents. Rearrangement and cyclizalion occurs on treatment of the anilinosulfonium salts with EtjN. The initial cyclization product is a 3-(methylthio)indole and these can be desulfurized with Raney nickel. Use of 2-(methylthio)acetaldehyde generates 2,3-unsubstituled indoles after desulfurization[2]. Treatment of 3-methylthioindoles with tri-fiuoroacetic acid/thiosalieylie acid is a possible alternative to Raney nickel for desulfurization[3]. 

There are two sequences in which the reaction can be carried out. For most anilines the first step is /V-chlorination which can be done with t-butyl hypochlorite[9]. However, for anilines with ER substituents it may be preferable to halogenate the thioester. The halogenation can be done with Cl2[lbl or SOjCljCU]. For some anilines simply adding f-butyl hypochlorite to a mixture of the aniline and thioester is satisfactory (Entries 1, 4, Table 7.6). 

Arylammes may also be named as arenamines Thus tive but rarely used name for aniline... 

A remarkable feature of these spectra is the resolution of individual rotational lines in such large molecules. [Note that the expanded specttum in, for example. Figure 9.47(a) covers only 5000 MFIz (0.17 cm )]. This is due partly to the very low rotational temperature (3.0 K for aniline and 2.2 K for aniline Ar), partly to the reduction of the Doppler broadening and partly to the very high resolution of the ring dye laser used. 

In the 1980s manufacturing capacity for aniline underwent some major changes. It is estimated that aniline capacity utilization was about 50% of nameplate capacity when Aristech s new 91,000 t/yr plant came on stream. That same year American Cyanamid closed its 23,000-t plant at Willow Island, W. Va., and withdrew from the aniline business. Mobay shut down its larger plant (45,000-t) at New Martinsville, W. Va. in 1983 and Du Pont idled its 77,000-tfacihtyinl984. 

Aniline prices in the past have been sensitive to the balance between supply and demand in the industry and this trend is likely to continue in the next decade. List prices in the early 1980s began at 0.97/kg, but declined to a low of 0.64/kg as a result of industry overcapacity. By the end of 1987, prices had reached 1.30/kg, and the price has remained firm due to strong demand for aniline. 

Rubber chemicals, primarily antioxidants (qv), stabiLhers, and antio2onants (qv), account for 12% of the demand for aniline woddwide. Important agricultural uses for aniline derivatives include fungicides, insecticides, animal repellents, and defoHants. It is estimated that less than 5% of the aniline produced in 1988 was consumed for agricultural chemicals. 

Amination of phenoHc derivatives is limited to specially developed catalytic processes for aniline and y -toluidine (3). More general conditions apply to amination of naphthols by the Bucherer reaction. Important intermediates made by a Bucherer reaction include Tobias acid and gamma acid. 

C-alkylation of secondary and tertiary aromatic amines by hexafluoroacetone or methyl trifluoropyruvate is performed under mild conditions [172] (equation 147) The reaction of phenylhydrazme with hexafluoroacetone leads selectively to the product of the C-hydroxyalkylation at the ortho position of the aromatic ring The change from the para orientation characteristic for anilines is apparently a consequence of a cyclic transition state arising from the initial N hydroxy alky lation at the primary amino group [173] (equation 148)... 

Compare the geometry of para-nitroaniline to those of both aniline and nitrobenzene. Is there any evidence for push-pull resonance contributors Is there shortening of bonds to the amino and nitro groups Are the bonds in the ring localized Is the dipole moment for para-nitroaniline smaller, larger or about the same as the sum of the dipole moments for aniline and nitrobenzene What does your result say about the importance of push-pull resonance contributors ... 

Phenol is also a precursor for anihne. The major process for aniline (C6H5NH2) is the hydrogenation of nitrohenzene (see Nitration of Benzene ). 

The value of pKb for aniline is 9.37 and that for 4-chloroaniline is 9.85 (see the following structures). Which is the stronger base Account for the difference in base strength. 

The second way in which the substituent R affects the charge distribution of the molecule is called the resonance effect (or sometimes the tautomeric or electromeric effect). This results when the molecule resonates among several electronic structures. For example, for aniline the structures... 

The adsorption pseudo-capacitance, Cg, is dominated by the factor ddjdE and hence a plot of C9 versus E gives direct information about the coverage. Figure 4 shows a Cg-E plot for aniline at mercury in aqueous solu-... 

The detection limits per chromatogram zone are 4-20 ng substance for aniline derivatives [52] and 3-KX) ng substance for indole derivatives [2, 4, 5, 32, 53].But some substances, e.g. dihydroergosine [11] and PR toxin and PR imine [44] can be detected in quantities smaller than 1 ng. 

A convenient modification of the Gassman oxindole synthesis was reported using ethyl (methylsulfinyl)acetate (101) activated by oxalyl chloride to generate the same chlorosulfonium salt 102 normally generated from ethyl (methylthio)acetate 100 and elemental chlorine <96TL4631>. Thus, treatment of the sulfoxide 101 with oxalyl chloride, followed by the addition of the desired aniline, triethylamine, and finally acid cyclization of 103 affords the oxindoles 104. This procedure is particularly convenient for reactions carried out on smaller scales and for anilines that ate susceptible to electrophiUc halogenation. 

The degradation of aniline may be induced by aniline, although both 3- and 4- chloroani-line, which are poor substrates, were able to induce the enzymes for aniline degradation in a strain of Pseudomonas sp. (Konopka et al. 1989). This strain was able to degrade aniline in the presence of readily degradable substrates such as lactate. 

Hydrolysis of benzanilide. Place 5 g. of benzanilide and 50 ml. of 70 per cait. sulphuric acid in a small flask fitted with a reflux condenser, and boil gently for 30 minutes. Some of the benzoic acid will vapourise in fbe steam and solidify in the condenser. Pour 60 ml. of hot water down the condenser this will dislodge and partially dissolve the benzoic acid. Cool the flask in ice water filter off the benzoic acid (aniline sulphate does not separate at this dilution), wash well with water, drain, dry upon filter paper, and identify by m.p. (121°) and other tests. Render the filtrate alkaline by cautiously adding 10 per cent, sodium hydroxide solution, cool and isolate the aniline by ether extraction. Recover the ether and test the residue for aniline (Section IV, 100). 

A much improved, chromatography-free process for aniline 6 was developed with -90% overall yield. The remarkable efficiency for each transformation rendered this intermediate 6 to be suitable for out-sourcing without further optimization. 

The aniline molecule is thus stabilised with respect to the anilinium cation, and it is therefore energetically unprofitable for aniline to take up a proton it thus functions as a base with the utmost reluctance (p Ka = 4 62, compared with cyclohexylamine, pKa = 10-68).Thebase-weakening effect is naturally more pronounced when further phenyl groups are introduced on the nitrogen atom thus diphenylamine, Ph2NH, is an extremely weak base (pKa = 0-8), while triphenylamine, Ph3N, is by ordinary standards not basic at all. 

Bosch LI, Mahon MF, James TD (2004) The B-N bond controls the balance between locally excited (LE) and twisted internal charge transfer (TICT) states observed for aniline based fluorescent saccharide sensors. Tetrahedron Lett 45(13) 2859-2862... 

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