Aminosulphonic acid

The sulphonic acids are usually prepared by the action of sulphuric acid upon a compound. The concentration of the acid and the temperature of reaction are varied according to the reactivity of the compound. Often oleum is used or even chiorosulphonic acid. Alternatively sulphur trioxide complexed to pyridine or dioxan can be used with reactive substrates. Aminosulphonic acids such as sulphanilic and naphthionic acids are most conveniently prepared by heating the sulphate of the amine at ISO C. 

The procedure is not usually applicable to aminosulphonic acids owing to the interaction between the amino group and the phosphorus pentachloride. If, however, the chlorosulphonic acid is prepared by diazotisation and treatment with a solution of cuprous chloride in hydrochloric acid, the crystalline chlorosulphonamide and chlorosulphonanilide may be obtained in the usual way. With some compounds, the amino group may be protected by acetylation. Sulphonic acids derived from a phenol or naphthol cannot be converted into the sulphonyl chlorides by the phosphorus pentachloride method. 

In the aminosulphonic acids the electrochemical character of both substituents is appreciably weakened, as it is in aminocarboxylic acids... 

As a rather strongly hydrophilic anion, nitrate requires an ISE membrane containing a strongly hydrophobic cation, as described on p. 169. This function was fulfilled in the first nitrate electrode from Orion Research by cation V [180] in nitro-p-cymene 5. The electrode can be used in the pH range 4-7. In other commercial electrodes, the ion-exchanger ion is a tetra-alkylammonium salt, for example in the electrode from Coming Co., substance XIII in solvent 6 [27]. An ISE with a renewable membrane surface was found to be very useful (see section 4.1 and fig. 4.4), in which the ion-exchanger solution contains the nitrate of crystal violet VII dissolved in nitrobenzene [191]. The NOj ISE also responds to nitrites that can be removed by addition of aminosulphonic acid. 

At the ordinary temperature chlorosulphonic acid dissolves sodium chloride, displacing hydrogen chloride and forming sodium chloro-sulphonate,11 this reaction being due to its acidic nature. It is of interest that ammonium chlorosulphonate can be synthesised by the action of sulphuryl chloride on aminosulphonic acid at 100° C.12... 

Polyhydroxy- phenols. amino acids, di- and polyamino compounds, amino alcohols. Sulphonic acids. Sulphinic acids. Salts. sulphinic acids, aminosulphonic acids and sulphonamides. Some diketones and /3-keto esters. Ethers and acetals. Lactones. Acyl halides. Diaryl ethers. intermediate reduction products of nitro compounds. Sulphones, sulphonamides of secondary amines, sulphides, sulphates and other sulphur compounds. 

These compounds are suggested if sulphur is present. If nitrogen is also present the compound may be an aminosulphonic acid. The infrared spectrum will show absorption at 3400-3200 cm -1 (OH str.) and 1150 and 1050 cm-1 (S=0 str. in a sulphonic add) or at 1090cm-1 (S=0 str. in a sulphinic acid). For derivative preparations for sulphonic acids see Section 9.6.26, p. 1284. The presence of an aromatic sulphinic add may be further confirmed by dissolving in cold concentrated sulphuric add and adding one drop of phenetole or anisole when a blue colour is produced (Smiles s test), due to formation of a para-substituted aromatic sulphoxide. The reaction is ... 

Thermodynamic parameters for the solution and ionization of sulphamic acid and the aminosulphonic acids H2N(CH2) S03H (n= 1,2) (19 and 20) and sulphanilic acid (21) were determined in dimethyl sulphoxide and water38. The three aliphatic acids are much weaker (2.1 ApXa 5.5) in dimethyl sulphoxide than in water and their heats of ionization are ca 30 kJ mol -1 more endothermic in dimethyl sulphoxide. Sulphamic acid (1) and the other acids are present principally as zwitterions in dimethyl sulphoxide just as in H20. 

The ionization constants at various temperatures and thermodynamic functions for sulphamic acid and several other aminosulphonic acids have been determined in formamide from electromotive force measurements40. The initial thermoelectric power (TEP) for hydrogen electrode thermocells has been determined for aqueous solutions of sulphamic acid at 29 °C over the concentration range 0.001 to 0.01 molal41. 

Another method of converting a carboxylic acid directly into its nitrile is to heat it at 200—240° with urea and aminosulphonic acid [53]. The yields obtained vary considerably with the structure of the acid 2-ClC H4.CN (85%), 4-ClC6H4.CN (56%), PhCN (75%), 4-NO2-C5H4.CN (72%), 2-cyanothiophen (30%). The absence of either of the nitrogenous reagents lowered the yield. A patent [54] recommends using the alkali metal salt of the acid under similar conditions. 

Barium salts of aromatic aminocarboxy 1 ic and aminosulphonic acids, 93. Other derivatives of aldehydes and ketones, 93. Determination of methylene,... 

Taurates and methyl taurates yield fatty acid and the aminosulphonic acid, methyltaurine, with the amino group protonated. 

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