Aromatic amines, use

The resolution of racemic ethyl 2-chloropropionate with aliphatic and aromatic amines using Candida cylindracea lipase (CCL) [28] was one of the first examples that showed the possibilities of this kind of processes for the resolution of racemic esters or the preparation of chiral amides in benign conditions. Normally, in these enzymatic aminolysis reactions the enzyme is selective toward the (S)-isomer of the ester. Recently, the resolution ofthis ester has been carried out through a dynamic kinetic resolution (DKR) via aminolysis catalyzed by encapsulated CCL in the presence of triphenylphosphonium chloride immobilized on Merrifield resin (Scheme 7.13). This process has allowed the preparation of (S)-amides with high isolated yields and good enantiomeric excesses [29]. 

Dehalogenation of aromatic amines using catalytic hydrogenolysis takes place easily, usually without the reduction of C=C, COO, C=N, and N02 groups.454,455 The hydrogenolysis of 5-bromo-3-(l-methyl-2-pyrrolidinyl)pyri-dine (38) on Pd/C in EtOH produces nicotine hydrobromide (39) (Scheme... 

The second way, called the Bunnett-Olsen method,30 makes the less drastic assumption that log activity coefficient ratios such as those in equation (7) are linear functions of one another, rather than cancelling out. From the definition of H0 in equation (8) we can write equation (11), where Am refers to the primary aromatic amines used in the determination of Ho, and then any specific activity coefficient ratio, say for the weak base B, is assumed to be linear in this according to equation (12) ... 

Aniline is an aromatic amine used in the manufacture of dyes, dye intermediates, rubber accelerators, and antioxidants. It has also been used as a solvent, in printing inks, and as an intermediate in the manufacture of pharmaceuticals, photographic developers, plastics, isocyanates, hydroquinones, herbicides, fungicides, and ion-exchange resins. It is produced commercially by catalytic vapor phase hydrogenation of nitrobenzene (Benya and Cornish 1994 HSDB 1996). Production of aniline oil was listed at approximately 1 billion pounds in 1993 (U.S. ITC 1994). Chemical and physical properties are listed in Table 1-2. 

The ratio of the two products is primarily affected by the nature of the mercury(II) salt and also by the reaction conditions. Since the formation of these compounds could result from either a kinetically or a thermodynamically controlled mercuration process, a study of the mercuration of 3 in the presence of aromatic amines using various mer-cury(II) salts has been more recently carried out in order to determine the conditions under which aminomercuration is reversible, and the results have been compared to those of the oxymercuration170. 

Oxidation of phenols and aromatic amines using HRP is generally of little synthetic value, as oligomers and polymers are the main products (5, 260). Under certain conditions oxidative coupling of phenols or naphthols to give biaryls can be achieved, but with low selectivity (262). In contrast, HRP can catalyze a number of useful oxidative N-and 0-deaIkyIation reactions that are relatively difficult to carry out synthetically. This area has been described in detail by Meunier (263). A method for the preparation of optically active hydroperoxides using HRP C has been developed (264). Optically pure (S)-hydroperoxides... 

The main aromatic amines used as diazo components are substituted anilines or naphthylamines and the coupling components substituted iV-aUcylanilines, phenols, naphthylamines and naphthols. Heteroaromatic diazo and coupling components are widely used in commercial azo dyestuffs. The main heterocyclic conpling components are pyrazalones (2.6) and, especially, pyridones (2.8). These are nsed to prodnce bright yellow and orange monoazo dyes, such as Cl Acid Yellow 72 (2.7) and Cl Disperse Orange 139 (2.9). ... 

Recently, Soleiman et al. [136] have published the synthesis of novel class of spiro-(3-lactams 237 using chloroacetylchloride and Schiff bases 236 in the presence of triethylamine and dioxane (Scheme 53). The new Schiff bases 236 were prepared by reaction of 234 with different aromatic amines using ethanol and piperidine as catalysts. 

Many of the organic aromatic amines used in hair dyes are strong sensitizers and oxidative dyes should be used with extreme caution. 

Table 1. Gas separation properties of polyimide-polydimethylsiloxane segmented copolymers as a function of the aromatic amine used for the hard segment [99]...

Mattioni, B.E., Kauffman, G.W., and Jurs, P.C., Predicting the genotoxicity of seconddary and aromatic amines using data subsetting to generate a model ensemble, J. Chem. Inf. Comput. Sci., 43, 949-963, 2003. 

Metaphenylene diamine (MPDA) is one of the most common of the aromatic amines used to cure epoxies. This product is amber to very dark in color. It is a solid that melts at 65°C and is generally mixed with the epoxy resin at that temperature. The molten liquid or vapors from MPDA can stain the skin and nearby structures rather badly. The para-isomer is reported to be carcinogenic, but the meta-isomer is free from this disadvantage. 

As an example, let us look at a method for acetylating aromatic amines in aqueous solution. This reaction has a special name—the Lumiere-Barbier method. We shall consider the acetylation of aniline PhNH2 (a basic aromatic amine) using acetic anhydride. The procedure for this reaction is as follows. 

Fig. 13.83. Representative aromatic amines used Fig. 13.84. Triazole formation from the diazotiza-in azo dye synthesis. tion of an ortho-diamine.

One-Pot Diazotization/Fluorodediazoniation of Aromatic Amines Using Hydrogen Fluoride... 

Sarafraz-Yazdi A and Es haghi Z. Liquid-liquid-liquid phase microextraction of aromatic amines using crown ethers by high-performance liquid chromatography with monolithic column. Talanta 2005 66 664-669. 

The discovery that exposure to exogenous chemicals could lead to cancer in humans was first made in the late 18th century, when Percival Pott demonstrated the relationship between cancer of the scrotum and the occupation of chimney sweepers exposed to coal tar/soot. Other examples noted later were scrotal cancers in cotton spinners exposed to unrefined mineral oils, and cancers of the urinary bladder in men who worked in textile dye and rubber industries due to their exposure to certain aromatic amines used as antioxidants. Experimental induction of cancer by chemicals was first reported in detail by Yamagiwa and Ichikawa in 1918, when repeated application of coal tar to the ear of rabbits resulted in skin carcinomas. Over the next few years, Kennaway and Leitch confirmed this finding and demonstrated similar effects in mice and rabbits from the application of soot extracts, other types of tar (e.g., acetylene or isoprene), and some heated mineral oils. These researchers also observed skin irritation sometimes accompanied by ulcers at the site of application of the test material. Irritation was thought to be an important factor in skin tumor development. However, not all irritants (e.g., acridine) induced skin cancer in mice and conversely, some purified chemicals isolated from these crude materials... 

One-Pot Diazotization/FIuorodediazoniation of Aromatic Amines Using Potassium Fluoride-... 

Zeng, Z., Qiu, W., Yang, M., Wei, X., Huang, Z., and Li, F., Solid-phase microextraction of monocyclic aromatic amines using novel fibers coated with crown ether, J. Chromatogr. A, 934, 51-57, 2001. 

Eskilsson, C. S., Davidsson, R., and Mathiasson, L., Harmful azo colorants in leather. Determination based on their cleavage and extraction of corresponding carcinogenic aromatic amines using modem extraction techniques, J. Chromatogr., 955, 215-227, 2002. 

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