Aminosulfonic acids

Sulfonation. Aniline reacts with sulfuric acid at high temperatures to form -aminoben2enesulfonic acid (sulfanilic acid [121 -57-3]). The initial product, aniline sulfate, rearranges to the ring-substituted sulfonic acid (40). If the para position is blocked, the (9-aminoben2enesulfonic acid derivative is isolated. Aminosulfonic acids of high purity have been prepared by sulfonating a mixture of the aromatic amine and sulfolane with sulfuric acid at 180-190°C (41). 

Monoaminoarenesulfonic acids exist in acid solution as zwitterions (2.3 in the case of sulfanilic acid), which are relatively insoluble in contrast to the corresponding bases (such as 2.4). For this reason the indirect method of diazotization is often employed in such cases. The aminoarenesulfonic acid is dissolved as the anion (2.4) by introducing the required amount of sodium carbonate or hydroxide, and nitrite is added to the approximately neutral solution, which is then run into mineral acid. Indirect diazotization is particularly recommended for the aminosulfonic acids of greater molecular mass but, contrary to some statements in the literature, the three anilinesulfonic acids themselves can be diazotized directly in suspension, the reaction proceeding quite smoothly after some practice. 

The diazotization of aminosulfonic acids, as well as that of amines with sparingly soluble salts, can be improved by the presence of dispersing agents. Most cationic textile auxiliary products may be used for this purpose. 

Aromatic aminosulfonic acids, which play a major role in connection with pigment lakes, are produced by sulfonating the corresponding nitro compound and then reducing it to an aminosulfonic acid. An alternative technique, known as baking process, involves exposing an amine/dihydrosulfate to a temperature of 200 to 300°C in order to effect rearrangement to p-aminosulfonic acid. Ortho-sulfonation prevails if the para position is occupied. In contrast to sulfonation techniques with sulfuric acid, this method avoids wastewater contamination with sulfuric acid. 

The list of important diazo components for the diazotization reaction includes aniline and a number of aniline derivatives, diamino diphenyl derivatives, and aromatic aminosulfonic acids. Important coupling components are acetoacetic arylides, pyrazolones, (3-naphthol, 2-hydroxy-3-naphthoic acid, and their aniline derivatives. 

This method is particularly useful for aromatic aminocarboxylic and aminosulfonic acids, which are often only sparingly soluble in dilute acid. The amino compound is dissolved in water or in weak alkali and combined with a stoichiometric amount of sodium nitrite, upon which the resulting solution is poured into a mixture of acid and ice. Alternatively, the process may be reversed by pouring the acid into the amine-nitrite mixture. 

Technically important pigments in this group - similar to (J-naphthol pigment lakes - contain aminosulfonic acids as diazonium components. Therefore, these pigments always contain two acidic groups for salt formation. 

Aromatic aminosulfonic acids are synthesized by a sequence of important industrial processes, including sulfonation of benzene. This is followed, wherever necessary, by chlorination, nitration, and reduction, or by aniline sulfonation, possibly involving subsequent baking [7,8]. 

Diazotization of the aminosulfonic acid and subsequent coupling onto the sodium salt of 2-hydroxy-3-naphthoic acid initially affords the monoazo compound in the form of its soluble sodium salt. Subsequent reaction with chlorides or sulfates of alkaline earth metals or with a manganese salt, frequently in the presence of a dispersion agent, or rosin or its derivatives, at elevated temperature yields the insoluble BONA pigment lake. 

The threshold limit for aromatic aminosulfonic acids, expressed as aniline sulfonic acid, must be below 500 ppm. 

Several countries have released identical or similar regulations as the European Regulation AP (89)1 regarding the threshold limits for metals, aromatic amines, aromatic aminosulfonic acids and PCB. 

Limit values for primary aromatic amines, aromatic aminosulfonic acids, certain cancerogenic amines (e.g., benzidine, 2-naphthylamine, 4-aminobiphenyl and 2-methyl-4-chloroaniline) and for polychlorinated biphenyls (PCB) should be viewed in the listed references of the specific country. 

Aromatic aminosulfonic acids, are limited with 500 ppm according to the Council of Europe and in Great Britain and Switzerland, a threshold limit value for PCB (25 ppm) exists as well for Great Britain and Switzerland and is recommended by the Council of Europe. 

His works concerning the improvement of the method of measurement for the boiling point of liquids (so-called improved Beckman method) and the measurement of molar conductivities of aminosulfonic acids are known as the pioneering works of physical chemistry or solution chemistry of Japan. 

Jung, R., Steinle, D. and Anliker, R. (1992) A comparison of genotoxicity and carcinogenicity data on aromatic aminosulfonic acids. Food Chem. Toxicol, 30, 635-660. 

Routes to 3,4-dihydro-2/7-1,2-benzothiazine dioxides (253) include the cyclization of aminosulfonic acids (252) or cyanosulfonamides (254). 2,4-Dihydro-1H-2,1 -benzothiazine dioxides (256) are normally prepared by thermolysis of the sodium sulfonates (255) or amino sulfonamides (257)... 

AMINOSULFONIC ACID AMMONIA (critical temp. (Table IV) Propane 132.4) 28.3 15 17 151,430... 

Scheme 23 Decomposition Pathways of (a) an a-Aminosulfonic Acid and (b) an a-Aminosulfonamide[1051...

As a more sensitive alternative test or an an additional confirmatory test, add 2 mL of aminosulfonic acid reducing reagent 5 min after adding oxalic acid solution. Let the solution stand for 5 min and then measure the absorbance at 815 or 650 nm (at the latter wavelength the sensitivity is reduced.) Plot a separate calibration curve. Read the concentration of analyte from the calibration curve. 

Benzidine can be diazotized at each amino group. It can then couple with two equivalents of the aminosulfonic acid. Coupling occurs ortho to the amino group since the para position is blocked by the sulfonic acid group. 

With the aminosulfonic acid (VII), in which a methyl group is para to the amino group, the main product is o-tolyenesulfonic acid (59%), and not the ethyl ether (37%).21 ... 

The successful application of sulfanyl amines in the diastereoselective and enantioselective synthesis of as-3,4-disubstituted /3-sultams has been reported (Scheme 56). The protocol is based on the oxidation of the 1,2-aminothiols 178 with hydrogen peroxide and ammonium heptamolybdate. Chlorination of the resulting /3-aminosulfonic acids was achieved using phosgene. The /3-aminosulfonyl chlorides 179 obtained were cyclized under basic conditions and without epimerization to yield the t -3,4-disubstituted /3-sultams 180 (>96% de, ee) (Table 13) <2005S1807>. 

Initially, an arylamine does not react as an activated aromatic compound with sulfuric acid but as a base instead anilinium hydrogen sulfates are produced (Figure 5.18). However, when the latter are heated, they decompose to give the starting materials reversibly. Only via the very small equilibrium amounts of free amine and free sulfuric acid does one observe the slow formation of the substitution product, an aromatic aminosulfonic acid. This aminosulfonic acid is a zwitterion, like an a-aminocarboxylic acid. 

This aminosulfonic acid has no definite melting point. On a Maquenne block a decomposition range of 335-380° was observed. 

Diazo compounds which contain a sulfo group are usually quite insoluble and precipitate as white or yellow crystals of the inner salt. Since many of the aminosulfonic acids themselves are also relatively insoluble, it is desirable to diazotize them by the indirect method. This is done by adding the necessary amount of nitrite to the solution of the sodium sulfonate, and pouring the solution into the acid. 

DOT UN 2967 mf H3NO3S mw 97.10 PROP White crystals nonhygroscopic solid. Mp 200° (decomp), bp decomp, d 203 12°. Very sol in H2O, liq NH3, formamide. SYNS AMIDOSULFONIC ACID AMIDOSULFURIC ACID AMINOSULFONIC ACID KYSELINA AMIDOSULFONOVA (CZECH) KYSELINA SULFAMINOVA (CZECH) SULFAMIDIC ACID SULPHAMIC ACID pOT)... 

AMINOSUCCINIC ACID see ARN850 AMINOSULFONIC ACID see SNK500... 

If both acidic and basic groups are present, the substance may be amphoteric and therefore soluble in both acid and base. Aromatic aminocarboxylic acids are amphoteric, like aliphatic ones, but they do not exist as zwitterions. They are soluble in both dilute hydrochloric acid and sodium hydroxide, but not in bicarbonate solution. Aminosulfonic acids exist as zwitterions they are soluble in alkali but not in acid. 

Aminosulfonic acids of the naphthalene and biphenyl series also have been deaminated, but the smoothness of the reaction cannot be estimated from the available experimental data. 

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