Aniline Uses

Polyaniline (PANI) can be formed by electrochemical oxidation of aniline in aqueous acid, or by polymerization of aniline using an aqueous solution of ammonium thiosulfate and hydrochloric acid. This polymer is finding increasing use as a "transparent electrode" in semiconducting devices. To improve processibiHty, a large number of substituted polyanilines have been prepared. The sulfonated form of PANI is water soluble, and can be prepared by treatment of PANI with fuming sulfuric acid (31). A variety of other soluble substituted AJ-alkylsulfonic acid self-doped derivatives have been synthesized that possess moderate conductivity and allow facile preparation of spincoated thin films (32). 

The Faux process is a modification of the Bechamp reaction that was discovered in 1854. It has been used for the reduction of nitrobenzene to aniline using metallic iron ... 

Other aniline uses are projected to grow at rates ranging from 0 to 4% annually, with agricultural chemicals at the low end and mbber chemicals at the upper end of this range. 

An example of the use of copper as a catalyst is Acid Blue 25 [6408-78-2] (Cl 62055) in which l-amino-2-sulfonic-4-bromoanthraquinone is condensed with aniline using copper salts (Ullmann reaction) (314). Another example is oxidation to the tria2ole of Direct YeUow 106 [12222-60-5] (Cl 40300) (315,316). 

Phenazine mono-N-oxides have also been prepared from nitrobenzene derivatives. Condensation of nitrobenzene with aniline using dry NaOH at 120-130 °C results in modest yields of phenazine 5-oxide, although the precise mechanism of this reaction is not well understood (57HC(ll)l) with unsymmetrical substrates it is not possible to predict which of the isomeric fV-oxides will be produced. Nitrosobenzene derivatives also function as a source of phenazine mono-fV-oxides thus, if 4-chloronitrosobenzene is treated with sulfuric acid in acetic acid at 20 °C the fV-oxide is formed (Scheme 21). 

Benzylaniline reacts with benzyl chloride to form diben-zylaniline. If the proportion of aniline used is less than that given, the yield of benzylaniline is lowered, and separation... 

Synthesis of polysubstituted anilines using the Diels-Alder reaction of methyl-5-aminofuroate [143]... 

Much research has been carried out into direct amination of aromatic substrates, typified by the direct conversion of benzene to aniline using ammonia and a catalyst. Although there have been many patented routes conversions, are normally low, making them uneconomic. Modem catalysts based on rhodium and iridium, together with nickel oxide (which becomes reduced), have proved more active,and such is the research activity in this area that it is only a matter of time before such processes become widely used. 

Marinescu L, Molbach M, Rousseau C, Bols M (2005) Supramolecular oxidation of anilines using hydrogen peroxide as stoichiometric oxidant. J Am Chem Soc 127(50) 17578-17579... 

This principle is exemplified by the following sequence of substituted anilines used as diazo compounds, whose coupling energy decreases with an increasingly electron donating substitution pattern on the aniline skeleton ... 

A surprising A-carboxylation of amines and anilines using (33) as EGB in MeGN-Et4NGl04 has been reported [114]. Despite the fact that amines and anilines have pK... 

Table 10. Products Yield and ee s of asymmetric ring opening reaction of ieso-stilbene oxide with aniline using complexes 70-72...

Table 11. Asymmetric catalytic ring opening of meso stilbene oxide with aniline using...

Kureshy, R. I. Singh, S. Khan, N. H. Abdi, S. H. R. Suresh, E. Jasra. R. V. (2006) Facile enantioselective ring-opening reaction of meso-epoxides with anilines using (5)-(-)-BlNOL-Ti complex as a catalyst., Ewr. J. Org. Chem., 1303-1309. 

Aniline itself undergoes intramolecular coupling and further oxidation to give aniline black. Poly(aniline) can be deposited as a thin coherent film on the anode by continuously cycling the potential between -0.2 and 0.8 V vs. see [165], Oxidation of aniline using manganese(ll) - roanganese(IIl) as mediator in dilute sulphuric... 

This process is used principally in Europe. It was first developed in 1854 for the production of aniline. Nitrobenzene was reduced to aniline using metallic iron, hence the process was termed the aniline or nitrobenzene process. Iron oxides were formed as unusable, grey/black products. Around 1925, Laux found that addition of iron chloride modified the process so that iron oxides suitable for use as pigments could be produced. With this additive alone, magnetite with a high tinting strength results, i. e. 

It is interesting to note that similar steric conditions are required for sweetness of nitro- and cyano-anilines. Using the W parameters defined similarly to those of aldoximes as shown in Fig. 8, the combined data for fourteen 2-substituted... 

Wester et al (Ref 24) patented an industrial method of preparation of diarylamine, and more particularly of DPhA. Essentially the process comprises heating aniline in an autoclave at pressures betw 100 and 200psi, in the presence of ferric chloride catalyst in an amount betw 0.3% to 8.0% by wc of the aniline used. Yields as high as 58.8% were reported after heating for only 8 hrs at l60psi... 

The samples shall be added dropwise and the flasks swirled to prevent local overheating. Stopper each flask immediately and, after 3 to 5 mins of standing,wash down the contents of 1st flask with 100 ml w (neutral to phenol-phthalein) and titrate with N/2 HC1 to phpht end point. Cool 2nd flask, wash down the contents with 100 ml of aq methanol (75 25) (neutral to phpht) and titrate with N/2 carbonate-free NaOH to a phpht end point. Titrate a blank so In consisting of 100 ml of aq methanol and 20 ml aniline using 0.1N carbonate-free NaOH... 

Suatoni, J. C., R. E. Snyder, and R. O. Clark, Voltametric studies of phenol and aniline using ring substitution , Anal. Chem., 33, 1894-1897 (1961). 

A study of the reaction of PGE and aniline using high purity reagents and excluding traces of hydroxylie materials, has been reported by Enikolopiyan 56). This demonstrated that amine-epoxide addition can occur in the absence of acidic catalysts, and the observed overall rate was second-order in amine concentration. 

H0 is known as the Hammett acidity function, and the series of substituted anilines used to establish the scale are called Hammett indicators. 

It was later shown by Laurence and coworkers that there are significant systematic differences between P values of solvents obtained with indicators with an oxygen donor atom and those with a nitrogen donor atom (Nicolet and Laurence 1986). These authors recommended the use of a single indicator, preferably 4-nitrophenol relative to 4-nitroanisole or else 4-nitroaniline relative to 4-nitro-N,N-di/rae%>/aniline (rather than 4-nitro-N,N-die// y/aniline used by Kamlet and Taft 1976), to establish a basicity scale. The main point of difference is with respect to solvents that do not have an oxygen donor atom, such as amines, pyridines, and sulfides. In order to save the P scale, Kamlet and Taft proposed a family-dependent covalency parameter, equal to -0.20 for P=0 bases, 0.00 for C=0, S=0, and N=0 bases, 0.20 for -O-bases, 0.60 for pyridines, and 1.00 for amines, for use in linear free energy relationships (Kamlet etal. 1985). 

A direct enantioselective Mannich synthesis of /3-amino- -oxyaldchydcs - from unmodified /I-oxyaldehydes and anilines - uses L-proline to give high des and ees.34... 

Sterically controlled regioselective para-substitution of aniline has been achieved by introduction of sterically demanding l-isopropyl-2-methylpropyl or triisopropylsilyl groups at the nitrogen of aniline using a lithiation-substitution sequence.71... 

Methemoglobinemia has resulted from exposure to aniline used as a vehicle in indelible laundrymarking inks, particularly those used to mark diapers. This condition was first recognized in 1886, and cases were reported for many decades thereafter. Infants who develop methemoglobinemia from this source suffer a 5 to 10% mortality rate. The skin of infants (particularly in the genital area see Section 6.4) is more permeable to aniline than that of adults, and infant blood is more susceptible to methemoglobinemia. 

Brillas E, Mur E, Casado J. Iron (II) catalysis of the mineralization of aniline using a carbon-PTFE 02 fed cathode. J Electrochem Soc 1996 143 L49-L53. 

MDI [4,4 -methylenebis (phenylisocyanate)] accounted for almost 85% of the worldwide demand for aniline in 2000. MDI is used primarily to make rigid polyurethane foam and polyurethane elastomers. MDI growth is expected to be 6% to 8% per year during the 2000 s as its use continues to increase in the construction industry (the largest user of rigid polyurethane foam) and the auto industry (the largest user of reaction-injection molding plastics). The aniline uses are shown in Table 20.3255. 

Draw the important resonance structures for aniline. Use the curved arrow convention to show how the electrons are moved to create each new resonance structure. Discuss the relative contribution of each to the resonance hybrid and the overall resonance stabilization of the compound. 

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