Naphthol-sulphonic acids

Baldauf, H., Scoen.Herr, J., and Schubert, H., Alkane Dicarboxilic Acids and Amino Naphthol-Sulphonic Acids - a New Reagent Regime for Cassiterite Flotation, International Journal of Mineral Processing, Vol. 15, pp. 117-133, 1985. 

Naphthylamine Sulphonic Acids and Naphthol Sulphonic Acids... 

The most important dyes derived from naphthylamine sulphonic acids and from naphthol sulphonic acids result from coupling them as azo compounds with other rings. This coupling is effected through a diazonium salt made by diazotizing an amine and bringing this di-... 

Fast Red B, Bordeaux B.—One more example of an azo dye derived from naphthalene may be given in which naphthylamine is diazotized and coupled as an azo compound with a naphthol sulphonic acid. The compound 2-naphthol 3-6-di-sulphonic acid is a dyestuff intermediate known as R-salt (red salt) because it is used in making red dyes. When alpha-naphthylamine is diazotized and coupled with R-salt the resulting azo dye is known as fast red B or Bordeaux B. Its constitution is... 

The stability of the mercurated a-naphthols to vards alkali halides decreases from the chlorides to the iodides, potassium iodide eliminating the mercury as mercuric iodide. Diacetoxymercuri-a-naphthol is stable to ammonium sulphide. 2 Acetoxymercuri-1 4-naphthoi monosuiphonic acid is very stable towards ammonium sulphide, but w hen warmed with sodium chloride in acetic acid solution, mercury is split out, and l-acetoxymercuri-2 6-naphthol sulphonic acid has similar properties. l-Acetoxymercuri-jS-naphthol is not blackened by cold ammonium sulphide, but gives mercuric sulphide on heating. 

Por -naphthol disulphomc acid P, see German Patent, 143448 dij g-naphthol sulphonic acid, see German Patent, 143726. 

It may be as well to take this opportunity of remarking that a method often used for determining the constitution of naphthol-sulphonic acids appears not to be trustworthy, as molecular changes, which occur so frequently in the naphthalene series, appear to take place here also. This is the method depending on the conversion of the acids into chloronaphthalenes by means of phosphorus pentachloride. Indeed the results so obtained often differ from all others. 

This body [61] is known as CroceTn Scarlet 3B, and although not producing fast shades is used, in cotton-dyeing. Crocein Scarlet 7 B is a dyestuff of somewhat bluer shade, and is obtained from orthoamidoazotoluenesulphonic acid in the same manner. The tetrazo-dyes prepared from y3-naphthol- -sulphonic acid give soluble crystalline calcium salts, while those from the other acid give amorphous and insoluble calcium salts. 

They are produced technically by two methods, either by direct sulphonation of the naphthylamines or by heating the naphthol-sulphonic acids with ammonia (he., a compound yielding ammonia on heating). 

In 1876 the dye firm of Poirrier in Paris introduced what were called oranges , which were said in the Paris Exhibition in 1878 to have been discovered by Z. Roussin. These dyes were investigated by Hofmann,who concluded that they were formed by coupling diazobenzene with naphthol-sulphonic acid, and Witt announced that the dye tropaeoline, then made in England, was formed from sulphonic acids of hydroxy and amino azo-bodies . 

Schaffer s acid, CioHg04S. 2-hydroxy-7-naphthalene sulphonic acid. Obtained by sulphonating 2-naphthol with a small amount of sulphuric acid at a higher temperature than is used for the preparation of crocein acid. A valuable dyestuff intermediate. 

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. 

Supplement (combined with Volume XII) XI, 2nd 1933 1605-1739 2. Sulphonic acids Benzenesulphonic acid, 26. p-Toluenesulphonic acid, 97. Naphthalene - sulphonic acid, 155. Hydroxy-Sulphonic acids Phenol-sulphonic acid, 234. Naphthol-sulphonic... 

Phosphorus and Silicon in Waters, Effluents and Sludges [e.g. Phosphorus in Waters, Effluents and Sludges by Spectrophotometry-phosphomolybdenum blue method. Phosphorus in Waters and Acidic Digests by Spectrophotometry-phosphovanadomolybdate method. Ion Chromatographic Methods for the Determination of Phosphorus Compound, Pretreatment Methods for Phosphorus Determinations, Determination of silicon by Spectrophotometric Determination of Molybdate Reactive Silicon-1 -amino-2-naphthol-4, sulphonic acid (ANSA) or Metol reduction methods or ascorbic acid reduction method. Pretreatment Methods to Convert Other Eorms of Silicon to Soluble Molybdate Reactive Silicon, Determination of Phosphorus and Silicon Emission Spectrophotometry], 1992... 

If in the last phase the different sulphonic acids of /d-naphthol are employed, arious shades of red, known as Crocci7is ate produced. Thus it appears that the colour deepens from orange to led with the introduction of a second azo-group. 

Calmagite. This indicator, l-(l-hydroxyl-4-methyl-2-phenylazo)-2-naphthol-4-sulphonic acid, has the same colour change as solochrome black, but the colour change is somewhat clearer and sharper. An important advantage is that aqueous solutions of the indicator are stable almost indefinitely. It may be substituted for solochrome black without change in the experimental procedures for the titration of calcium plus magnesium (see Sections 10.54 and 10.62). Calmagite functions as an acid-base indicator ... 

Discussion. Small quantities of dissolved silicic acid react with a solution of a molybdate in an acid medium to give an intense yellow coloration, due probably to the complex molybdosilicic acid H4[SiMo12O40]. The latter may be employed as a basis for the colorimetric determination of silicate (absorbance measurements at 400 nm). It is usually better to reduce the complex acid to molybdenum blue (the composition is uncertain) a solution of a mixture of l-amino-2-naphthol-4-sulphonic acid and sodium hydrogensulphite solution is a satisfactory reducing agent. 

Reducing agent. Solution A dissolve 10 g sodium hydrogensulphite in 70 mL water. Solution B dissolve 0.8 g anhydrous sodium hydrogensulphite in 20 mL water, and add 0.16 g l-amino-2-naphthol-4-sulphonic acid. Mix solution A with solution B, and dilute to 100 mL. 

Conant and Peterson123 made the first kinetic study of the coupling of diazonium ions with aromatics, and measured the rates of reaction of diazotised aniline and its 2-MeO, 4-Me, 4-Br and 4-S03H derivatives with the sodium salts of 4-hydroxybenzenesulphonic acid, 2-naphthol-3,6-disulphonic acid, 1-naphthol-3,8-disulphonic acid, and l-naphthol-4-sulphonic acid. The reaction was second-order, viz. 

P-Bromonaphthalene. The preparation from p-naphthylamine, which has carcinogenic properties, is avoided by the use of 2-naphthylamine-1-sulphonic acid ( 2-amino-1-naphthalenesulphonic acid ) the latter is obtained commercially by cautious treatment of p-naphthol with sulphuric acid—the SOjH group first enters the 1-position—followed by the Bucherer reaction. Diazotisation and reaction with cuprous bromide yields 2-bromonaphthalene-l-sulphonic acid heating with sulphuric acid eliminates the sulphonic acid group to give 2-bromonaphthalene. 

Early studies of the affinity of acid dyes for wool revealed noteworthy correlations with dye structure. For example, in four pairs of monoazo dyes differing only by replacement of a benzene by a naphthalene nucleus, the affinity increase in each pair was consistently within the range -4-6 to -6.3 kj/mol. In three related pairs of dyes, an additional sulpho group reduced the affinity by about -4 kj/mol. In a series of alkylsulphuric acids (ethyl, octyl, dodecyl) and in two series of monoazo dyes containing alkyl chains of increasing length, the increment per methylene group was consistently about -1.66 kj/mol. A close correlation between affinity and Mr was also obtained for a series of substituted phenylazo-l-naphthol-4- sulphonic acid dyes [115]. 

Of far greater importance are the sulphonated aminonaphthols, in which the versatility conferred by the presence of both an amino and a hydroxy group makes them among the most important group of azo intermediates. Three are outstanding, namely, 6-amino-l-naphthol-3-sulphonic acid (4.16 J acid), 7-amino-l-naphthol-3-sulphonic acid (4-17 y acid) and H acid (4.2), which couple under the relevant conditions of pH at the arrowed positions. 

This displacement is accomplished by heating the sulphonated derivative at a high temperature with sodium or potassium hydroxide [64]. Typical is the preparation of 2-naphthol (4.15) from naphthalene-2-sulphonic acid (Scheme 4.21). Displacement of the sulphonic acid group occurs more readily when it is located at the a- rather then at the P-position, the former requiring a fusion temperature of about 200 °C and the latter one of about 250 °C. This difference in reactivity can be exploited to prepare naphtholsulphonic acids by fusion of suitable naphthalenedisulphonic acids. 

In the above reaction mechanisms it is noteworthy that the sulphonic acid group introduced has been shown to enter at the 3-position and not the 4-position as previously postulated. A consequence of this situation is that an attempted Bucherer reaction on a naphthol (or a naphthylamine) carrying a sulphonic acid group located meta to the hydroxy (or amino) group would require a second sulphonic acid group to be introduced at this position. Since it is impossible to locate two sulphonic acid groups on the same carbon atom, these compounds cannot undergo the transformation. 

The preparation of 2-naphthol by high-temperature sulphonation of naphthalene followed by alkali fusion of the resulting naphthalene-2-sulphonic acid has been mentioned previously. Further sulphonation of 2-naphthol yields several useful naphtholsulphonic acids and conditions can be chosen to make one or other of these compounds the main product. The initial product is the unstable 2-naphthol-l-sulphonic acid, which readily rearranges to 2-naphthol-6-sulphonic acid (4-36 Schaeffer s acid). Further sulphonation leads to 2-naphthol-6,8-disulphonic acid (4-37 G acid) at low temperature and 2-naphthol-3,6-disulphonic acid (4.38 R acid) at higher temperature. 

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