1- Naphthol sulphonates

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... 

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. 

The pH required for the precipitation of C is about 5-5 this can be more conveniently achieved by the use of either nitrazine (sodium dinitrophenyl-azo-naphthol sulphonate) or bromocresol purple (dibromo-o-cresol-sulphone-phthalein) test-papers. All that is necessary is to add the sodium hydroxide solution until the appropriate colour change is produced it is best to use a... 

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 . 

Can be coupled in the 4-position with dia-zotized bases to give a series of azo dyestuffs more usually it is first sulphonated to give a valuable series of intermediates for solubilized azo dyestuffs. The nitro-l-naphthols are themselves dyestuffs, e.g. 2,4-dinitro-l-naph-thol ( naphtol yellow ). 

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. 

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. 

Solochrome black (eriochrome black T). This substance is sodium 1-(1-hydroxy-2-naphthylazo)-6-nitro-2-naphthol-4-sulphonate, and has the Colour Index reference C.I. 14645. In strongly acidic solutions the dye tends to polymerise to a red-brown product, and consequently the indicator is rarely applied in titrations of solutions more acidic than pH = 6.5. 

Solochrome dark blue or calcon ( C.1.15705). This is sometimes referred to as eriochrome blue black RC it is in fact sodium l-(2-hydroxy-l-naphthylazo)-2-naphthol-4-sulphonate. The dyestuff has two ionisable phenolic hydrogen atoms the protons ionise stepwise with pK values of 7.4 and 13.5 respectively. An important application of the indicator is in the complexometric titration of calcium in the presence of magnesium this must be carried out at a pH of about 12.3 (obtained, for example, with a diethylamine buffer 5 mL for every 100 mL of solution) in order to avoid the interference of magnesium. Under these conditions magnesium is precipitated quantitatively as the hydroxide. The colour change is from pink to pure blue. 

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. 

Kinetic isotope effects have not been observed in the reaction of 1-naphthol-4-sulphonic-2-acid with 2-methoxydiazobenzene127, imidazole-2,4,5-d3 with 4-diazobenzene sulphonic acid128, or indole-3- / with 4-nitrodiazobenzene12S, nor has base catalysis been observed in those cases where it has been measured in each of these reactions one or both of the reagents is relatively reactive. 

FIRST-ORDER RATE COEFFICIENTS SULPHONATE WITH Br (104fci) FOR i IN AQUEOUS REACTION OF 2-NAPHTHOL-6,8-DIBUFFERS AT 20 °C303 ... 

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