Sulfonation, of aromatic amines

Direct sulfonation of aromatic amines is even possible. This is very surprising because in sulfuric acid essentially all the amine will be protonated. The protonated amine would react in the meta position just like Ph—NMelj but in these reactions the para-sulfonic acid is formed. 

The sulfonation of aromatic amines such as aniline can give a mixture of products that must be separated prior to dye synthesis. 

The rearrangement of arylaminosulfuric acids (arylsulfamic acids) 220 to the corresponding ring-sulfonated anilines 221 and 222 was of great interest from both mechanistic and synthetic viewpoints, because these above-named acids have been postulated as intermediates in the sulfonation of aromatic amines with sulfuric acid305 (equation 85). 

The same method can be used with anilines because para-sulfonation of aromatic amines is possible. This seems surprising because in sulfuric acid essentially all the amine will be protonated. You might expect the resulting ammonium ion to react in the meta position (because NH is no longer electron-rich) but instead the para-sulfonic acid (sulfanilic acid) is formed. At the high temperature of the reaction, it is probable that any meta-substituted product reverts to the starting material, while the para-sulfonic acid accumulates because it is stabilized by delocalization and is less hindered. 

Substituent effect, in nitration 253 in nitrosation 314 on basicity 176-179, 181-187 on inductive effect 209 on reactivity of C=N linkage 352 Sulfonation, of aromatic amines 255, 256... 

A Methylanthrapyridone and Its Derivatives. 6-Bromo-3-methylanthrapyridone [81-85-6] (75) is an important iatermediate for manufacturiag dyes soluble ia organic solvents. These solvent dyes are prepared by replacing the bromine atom with various kiads of aromatic amines. 6-Bromo-3-methylanthrapyridone is prepared from 1-methyl amino-4-bromoanthra quin one (43) by acetylation with acetic anhydride followed by ring closure ia alkaU. The startiag material of this route is anthraquiaoae-l-sulfonic acid (16). 

Reaction of a-isocyano-a, / -unsaturated sulfones with primary aliphatic amines affords 1,5-disubstituted imidazoles 59 (equation 56)48. The reaction of aromatic amines such as aniline is too slow to be of practical use. Results of the preparation of 59 are listed in Table 5. 

Benzene and naphthalene sulfonate moieties are present in the structures of many dyes that can be found in large amounts in wastewaters from textile and food industries. Even if wastes are decolored before the final discharge, not enough attention is nowadays devoted to the identification of possible uncolored degradation products, potentially toxic, that form during the decolorization process and are discharged into the aquatic systems. Besides sulfonate derivatives, aromatic amines have also been reported as possible degradation products of dyes [109],... 

Because the sensitivity of the detector decreases with decreasing analyte ionization, the pH of the mobile phase should be chosen to maximize solute dissociation. For example, anions with pKa values above 7 are not detectable by conductivity detection. However, conductivity detection is often the preferred method for organic acids with carboxylate, sulfonate, or phospho-nate functional groups, since the pKa values are below 5. For cations, most aliphatic amines have pKa values around 10 and are readily detected by conductivity detection. The pKa values of aromatic amines, however, are in the range 2 to 7, which is too low to be detected by suppressed conductivity. Sensitivity by nonsuppressed conductivity is also poor, so these amines are monitored by UV absorption or pulsed amperometric detection. 

The use of low capacity surface sulfonated cation exchange resin for the liquid chromatographic separation of aromatic amines provides a rapid analytical technique for industrial hygiene surveys. A wide variety of amines can be analyzed by the same technique with good sensitivity. 

In the sulfonation of aromatic substrates containing a free amino group with hot concentrated sulfuric acid, the initially formed amine sulfate may rearrange to yield the required sulfonic acid. Thus, when aniline (31) is heated with concentrated sulfuric acid at 200°C (the baking process ), the amine sulfate (32) is probably converted into phenylsulfamic acid (33) which subsequently rearranges by migration of the sulfonic acid group into orthanilic acid (34) and finally to the most thermodynamically stable sulfanilic acid (35) (Scheme 18). 

From a theoretical point of view this is an extremely interesting reaction. The displacement of a hydroxyl group from a saturated carbon atom appears to be unknown in basic solution. The fact that amino-methane sulfonic acid can be isolated from the bisulfite addition product of formaldehyde on treatment with ammonia does not prove, of course, that a direct displacement, such as is indicated in XVI to XVII, actually occurred. Furthermore, it is quite clear that preliminary formation of an imine (XVIII) is not necessary for the reaction of aromatic amines with sodium bisulfite (steps XIX to XVIII to XVII, etc.). 1-Dimethyl-aminonaphthalene-4-sulfonic acid (XX) and l-aminonaphthalene-4-sulfonic acid (XIX) show similar reaction kinetics 16a when treated with sodium bisulfite, yet with the tertiary amine (XX) it is not possible to write an imino structure corresponding to XVIII. 

Absorphon of CO2 in aqueous solutions of MEA absorption of H2S and mercaptans in aqueous soluhons of alkanolatnines and caushc soda absorption of carbon monoxide in aqueous cuprous ammonium chloride solutions absorphon of lower olefins in aqueous soluhons of cuprous ammonium compounds absorption of pure chlorine in aqueous solutions of sodium carbonate or sodium hydroxide conversion of dithiocarbamates to thiuram disulfides sulfonation of aromatic compounds with lean SO3 recovery of bromine from lean aqueous solutions of bromides reactions of importance in pyrometallurgy absorphon of CO2 in aqueous solutions of caustic alkahes and amine absorption of O2 in aqueous solutions of sodium dithionite absorphon of O2 in aqueous sodium sulfite soluhons absorption of O2 in alkaline solutions containing the sodium salt of 1,4-napthaquinone- 2-sulfonic acid (NQSA) special case role of diffusion in the absorption of gases in blood in the human body. 

The Buchwald-Hartwig amination is an exceedingly general method for generating any type of aromatic amine from an aryl halide or aryl sulfonates.1,2 The key feature of this methodology is the use of catalytic palladium modulated by various electron-rich ligands. Strong bases, such as sodium ferf-butoxide, are essential for catalyst turnover. 

Huber133 has given several examples in a review of preparation of aromatic amine sulfonic acids by the baking process. 

OTHER COMMENTS used in the manufacture of dyes (aniline dyes, phthalein dyes), iodine compounds (iodides, iodates), antiseptics, and germicides used to reduce friction of hard surfaces, including glass and stainless steel also used as an alkylation and condensation catalyst in the preparation of aromatic amines, in sulfonations and sulfations useful as x-ray contrast media, as stabilizers, food and feed additives, and in water treatment important reagent in analytical chemistry has also been used in pharmaceuticals and medicinal soaps artificial isotopes of iodine are used in biochemical, biological, and chemical structure research. 

The palladium-catalyzed amination of aryl halides and sulfonates has emerged as a valuable method for the preparation of aromatic amines [2], Numerous ligands and catalysts have been reported to effect this type of cross-coupling. This reaction, known as the Hartwig-Buchwald amination, is shown in Eq. (1). 

However, substantial degradation occurred when the culture was made anaerobic nearly stoichiometric amounts of the corresponding aromatic amines were formed. Further degradation did not occur until the culture was reaerated, whereupon the amines were degraded to Krebs qrde intermediates by strain BN6, a member of the bacterial consortium known to be able to use a variety of aromatic amines as its sole carbon, nitrogen, and energy source. In addition to Mordant Yellow 3 (V), Acid Yellow 21 (VI), Amaranth (VII), Tartrazine (VIII), and 4-Hydroxyazobenzene-4 Sulfonic Acid (DC) were assayed for their ability to be metabolized in this system. 

The use of dry aryldiazonium salts of naphthalene-1-sulfonic [70], naphthalene-1,5-disulfonic [70], ZnCl2 complex [70], hexafluorophosphoric or tetrafluoroboric acid [61] in non-aqueous medium under as mild as possible reaction conditions is substantial to reach higher yields of biaryls. An alternative method for non-aqueous GBH reaction is the aprotic diazotation of aromatic amines with alkyl nitrites such as butyl or pentyl nitrite with subsequent arylation of aromatic compound, as demonstrated by Cadogan [71,72]. This method is realized by simple heating the mixture of aromatic amine, alkyl nitrite and liquid arene at an elevated temperature. When a mixture of 3-aminopyridine (46), benzene and pentyl nitrite is heated at reflux, 3-phenylpyridine (47) is obtained with a 55% yield [71], Scheme 16. 

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