Sulfanilic acid preparation

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). 

Bake sulfonation is an important variant of the normal sulfonation procedure. The reaction is restricted to aromatic amines, the sulfate salts of which ate prepared and heated (dry) at a temperature of approximately 200°C in vacuo. The sulfonic acid group migrates to the ortho or para positions of the amine to give a mixture of orthanilic acid [88-21-1] and sulfanilic acid [121 -57-3] respectively. This tendency is also apparent in polynuclear systems so that 1-naphthylamine gives 1-naphthy1amine-4-su1fonic acid. 

A) Diazotizalion of Sulfanilic Acid.—A mixture of 105 g. (0.5 mole) of sulfanilic acid dihydrate, 26.5 g. (0.25 mole) of anhydrous sodium carbonate, and 500 cc. of water is heated and stirred until all the sulfanilic acid has dissolved, and the solution is then cooled in an ice bath to 15° (sodium sulfanilate begins to crystallize at this temperature). A solution of 37 g. (0.54 mole) of sodium nitrite in 100 cc. of water is added and the resulting solution is poured at once onto a mixture of 106 cc. (1.25 moles) (Note i) of concentrated hydrochloric acid (sp. gr. 1.18) and 600 g. of ice contained in a 2-I. beaker. The solution, from which -benzenediazonium sulfonate separates on stirring, is allowed to stand in an ice bath for fifteen to twenty-five minutes, during which time the naphtholate solution is prepared. 

Incidentally, 31 contributes more to the hybrid than 32, as shown by bond-distance measurements. In benzenediazonium chloride, the C—N distance is 1.42 A, and the N—N distance 1.08 A, which values lit more closely to a single and a triple bond than to two double bonds (see Table 1.5). Even aromatic diazonium salts are stable only at low temperatures, usually only below 5°C, though more stable ones, such as the diazonium salt obtained from sulfanilic acid, are stable up to 10 or 15°C. Diazonium salts are usually prepared in aqueous solution and used without isolation, though it is possible to prepare solid diazonium salts if desired (see 13-20). The stability of aryl diazonium salts can be increased by crown ether complexion. ... 

Dibromoaniline has been prepared many times 3"5 6 n by bromination of sulfanilic acid and desulfonation of the product or its salts. Fuchs12 brominated sulfanilamide with free bromine and desulfonamidated it in the usual manner. Reduction of the corresponding nitro compound13 and other methods 14 also have been employed. 

Quinone may be prepared by the oxidation of aniline with dichromate or manganese dioxide and sulfuric acid.1 This is a more feasible commercial method than the one given. However, the oxidation of hydroquinone is more rapid and convenient and, hence is more desirable for use in the laboratory. Various materials have been oxidized by chemical means to give quinone they are quinic acid,2 hydroquinone,3 benzidine,4 -phenylene-diamine,5 sulfanilic acid,6 / -phenolsulfonic acid,7 arbutin,8 aniline black,9 and the leaves of various plants.10 Quinone is also formed by several other methods by the fermentation of fresh grass 11 by the action of iodine on the lead salt of hydroquin-... 

Phenyl-5-Pyrazolones as Coupling Components. Especially lightfast yellow shades are obtained by using l-phenyl-5-pyrazolone coupling components. The first representative of the class to appear was Tartrazine, C.I. Acid Yellow 23, 19140 [1934-21-0], which is prepared today from l-(phenyl-4 -sulfonic acid)-3-car-boxy-5-pyrazolone as the starting compound, obtained from oxaloacetic ester and phenylhydrazine-4-sulfonic acid and coupling with diazotized sulfanilic acid. 

The variation in the extinction coefficients of different bilirubin preparations is well known, and O Hagan (Ol) has suggested that the source of the bilirubin should always be stated. The relative extinction of the azobilirubin formed on coupling with diazotized sulfanilic acid depends on the solvent and the pH of the solution and may be altered by the... 

Sulfo and Sulfamido Groups. It has been shown that sulfanilic acid can be converted into p-sulfophenylarsonic acid (25-45%).49 60 By the ordinary Bart reaction p-sulfamidophenylatsonic acid (25%) may be prepared,60 although a better yield (57%) is obtained by a modified Scheller reaction.18 Apparently, metanilic acid and naphthionic acid will not yield the corresponding arsonic adds.18 61 Although m-sulfamido-phenylarsonic add is not available by the usual procedure it can be prepared in a 58% yield by the method of Scheller.18... 

An alternative method for the preparation of 5-aminothiatriazoles by way of an aza transfer reaction has been reported (780PP59). Benzenediazonium tetrafluoroborate or diazotized sulfanilic acid react rapidly at room temperature with thiosemicarbazides to give substituted aminothiatriazoles (equation 42). The procedure may be of importance with sensitive substrates since nitrous acid is avoided and the reaction proceeds under almost neutral conditions. 

These diazonium salts are good electrophiles for activated aromatic rings, such as amines and phenols, and this is how azo dyes are prepared. Diazotization of the salt of sulfanilic acid, which we have just made by sulfonation of aniline, gives an inner salt that combines with N,N-dimethylaniline to form the water-soluble dye, methyl orange. 

When a single product is sought, the baking reaction is often employed (Fig. 13.60). In this process, the sulfate salt of aniline is prepared, dried, and then baked in an oven under vacuum. The product in this case is the important dye intermediate, sulfanilic acid. Similarly, naphthylamine sulfonic acid can be produced, and if the para-position is occupied, sulfonation of an ort/m-position occurs (Fig. 13.61). 

Method II (Sample Preparation) Transfer approximately 0.5 g of sample, accurately weighed, into the titration flask. The stoichiometric factor (Fs) for Brilliant Blue is 2.52. Uncombined Intermediates and Products of Side Reactions Determine as directed for Method I in Uncombined Intermediates and Products of Side Reactions under Colors, Appendix IIIC. Calculate the concentrations of wt-sulfobenzal-dehyde and A/-cthyl-A/-(3-sulfobenzyl)-sulfanilic acid using the following absorptivities ... 

After the sulfanilic acid and nitrite solutions have been standardized, 1 N aniline solution is prepared. Pure aniline (200 cc.) is distilled from a small distillation flask (Fig. 7, page 71) at such a rate that the distillation is complete in 45 minutes. The aniline which comes over within a range of one-half degree between 184 and 185°C. is used for preparing the solution. The specific gravity should bie 1.0260 to 1.0265 at 17.5°. 

If the nitrite and sulfanilic acid solutions have been prepared correctly, 100 cc. of either the sulfanilic acid or the aniline solution should require exactly 100 cc. of the nitrite solution. 

A conventional preparation of 2,3-diphenyl-1,3-butadiene involves dehydration of meso-2,3-diphenyl-2,3-butanediol by acidic reagents including acetic anhydride,3-5 acetyl bromide,5 sulfanilic acid,6 and potassium hydrogen sulfate.7 Other procedures have been summarized2 previously. 

Oxidation of olefinic side chains with ozone to form aromatic aldehydes gives erratic results and therefore other oxidants are employed. For this purpose, the most widely used oxidant is nitrobenzene in dilute alkali the mixture is allowed to react at moderate temperatures for several hours. Thus, hydroxy benzaldehydes may be obtained from propenyl-phenols, which in turn are readily prepared by the Claisen rearrangement of Oalkyl ethers (method 100). Sodium dichromate in the presence of sulfanilic acid, which removes the aldehyde as it is formed, gives yields as high as 86% in the oxidation of isoeugenol and isosafrole. ... 

Polymethylquinones and certain polycyclic quinones are prepared by the oxidation of aminophenols and their polycyclic analogs. The latter substances are readily obtained by coupling the corresponding phenolic compound with diazotized sulfanilic acid followed by a reductive cleavage of the azo compound. 

The introduction of amino groups into phenols and ethers can be accomplished by the formation and reductive cleavage of their azo compounds. The diazotizing agent may be prepared from sulfanilic acid, and the reduction can be performed with sodium hydrosulfite. Excellent examples are found in the synthesis of l-amino-2-naphthol (85%) and 4-amino-l-naphthol (75%). ... 

In a 125-mL Erlenmeyer flask dissolve, by boiling, 4.8 g of sulfanilic acid monohydrate in 50 mL of 2.5% sodium carbonate solution (or use 1.33 g of anhydrous sodium carbonate and 50 mL of water). Cool the solution under the tap, add 1.9 g of sodium nitrite, and stir until it is dissolved. Pour the solution into a flask containing about 25 g of ice and 5 mL of concentrated hydrochloric acid. In a minute or two a powdery white precipitate of the diazonium salt should separate and the material is then ready for use. The product is not collected but is used in the preparation of the dye Orange II and/or Methyl Orange while in suspension. It is more stable than most diazonium salts and will keep for a few hours. 

D) Preparation of Methyl Orange. Add 2.6 g (0.015 moles) of sulfanilic acid to 20 ml of water, and then add 3 ml of 6 A sodium hydroxide solution. Warm slightly until solution is complete. Add 1 g of sodium nitrite, stir until the salt is dissolved, and cool to 25°. Pour this mixture, with constant stirring, into a beaker which contains 30 ml of water, 40 g of crushed ice, and 2 ml of concentrated sulfuric acid. Allow to stand for half an hour, adding ice if the temperature rises above 5°. Add a solution of 2 ml of dimethyl-aniline in 2 ml of hydrochloric acid. Stir, allow to stand for 15 minutes, and add 12 ml of 6 A sodium hydroxide and 50 ml of saturated salt solution. Cool for 10 minutes. Filter by suction, and wash the crystals with 10 ml of cold saturated salt solution. Press the crystals on the filter into a cake to drain well. To recrystallize, suspend the cake in 100-125 ml of distilled water and heat until solution is complete at 90-95°, adding more water if necessary. Filter the hot solution, and cool. Filter the crystals with suction, wash with alcohol and finally with ether. The yield is 3.5-4.0 g. 

For semimicro work section (A) or (C) is recommended. For macro work, beside the preparation of sulfanilic acid (section B), sections (C) and (D) may be adapted by increasing the quantities given 4-5 times and using a 250-ml flask. 

Introduction. The quinones are intermediate products in the oxidation of the aromatic nucleus. They may be prepared in some cases by the direct oxidation of aromatic hydrocarbons. For example, anthracene, naphthalene, and phenanthrene are oxidized to the corresponding quinones by chromic acid mixtures. Quinones are prepared more conveniently by oxidation of primary aromatic amines, particularly the p-substituted amines. p-Benzoquinone is obtained by the oxidation of aniline, p-toluidine, sulfanilic acid, p-aminophenol, and other similar compounds. Similarly the a-naph-thoquinone is obtained by oxidation of 1,4-aminonaphthol, and /9-naphthoquinone by the oxidation of 1,2-aminonaphthol. In the laboratory, although it is possible to prepare p-benzoquinone by the oxidation of aniline with acid-dichromate mixture, the method is tedious and the yield poor. Since hydroquinone is used extensively as a photographic developer and is made industrially, it is more convenient to prepare quinone by its oxidation. 

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