2- Naphthalenesulfonic acid reactions

Sulfonation. Sulfonation of naphthalene with sulfuric acid produces mono-, di-, tri-, and tetranaphthalenesulfonic acids (see Naphthalene derivatives), ah of the naphthalenesulfonic acids form salts with most bases. Naphthalenesulfonic acids are important starting materials in the manufacture of organic dyes (15) (see Azo dyes). They also are intermediates used in reactions, eg, caustic fusion to yield naphthols, nitration to yield nitronaphthalenesulfonic acids, etc. 

Generally, the sulfonation of naphthalene leads to a mixture of products. Naphthalene sulfonation at less than ca 100°C is kineticaHy controlled and produces predominandy 1-naphthalenesulfonic acid (4). Sulfonation of naphthalene at above ca 150°C provides thermodynamic control of the reaction and 2-naphthalenesulfonic acid as the main product. Reaction conditions for the sulfonation of naphthalene to yield desired products are given in Figure 1 alternative paths are possible. A Hst of naphthalenesulfonic acids and some of their properties is given in Table 1. 

Naphthalenesulfonic Acid. The sulfonation of naphthalene with excess 96 wt % sulfuric acid at < 80°C gives > 85 wt % 1-naphthalenesulfonic acid (a-acid) the balance is mainly the 2-isomer (P-acid). An older German commercial process is based on the reaction of naphthalene with 96 wt % sulfuric acid at 20—50°C (13). The product can be used unpurifted to make dyestuff intermediates by nitration or can be sulfonated further. The sodium salt of 1-naphthalenesulfonic acid is required, for example, for the conversion of 1-naphthalenol (1-naphthol) by caustic fusion. In this case, the excess sulfuric acid first is separated by the addition of lime and is filtered to remove the insoluble calcium sulfate the filtrate is treated with sodium carbonate to precipitate calcium carbonate and leave the sodium l-naphthalenesulfonate/7J(9-/4-J7 in solution. The dry salt then is recovered, typically, by spray-drying the solution. 

Naphthalenesulfonic acid can be converted to l-naphthalenethiol/T25 -J6 - by reduction of the related sulfonyl chloride this product has some utihty as a dye intermediate, and is converted by reaction with alkyl isocyanates to 3 -naphthyl-A/-alkylthiocarbamates, which have pesticidal and herbicidal... 

Naphthalenesulfonic Acid. The standard manufacture of 2-naphthalenesulfonic acid involves the batch reaction of naphthalene with 96 wt % sulfuric acid at ca 160°C for ca 2 h (13). The product contains the 1- and 2-isomers in a ratio of ca 15 85. Because of its faster rate of desulfonation,... 

By the nitrosation of 2-naphthalenol and the reaction of the nitroso compound with sodium bisulfite. By nitrosation/reduction of 6-hydroxy-2-naphthalenesulfonic acid. 

Other disazo dyes with good substantivity and high wet-fastness properties on polyamides are Acid Red 114 (40), made by coupling o-toHdine to phenol which is then coupled to G-acid, followed by reaction of the phenoHc hydroxyl group with -toluenesulfonyl chloride, and Acid Blue 113 (41) (metanilic acid — 1-naphthylamine — 8-anilino-1-naphthalenesulfonic acid). 

Interesting regioselectivities have been known for more than 100 years for azo coupling reactions with aminonaphthol derivatives such as 6-amino-4-hydroxy-2-naphthalenesulfonic acid (12.136, y-acid), 7-amino-4-hydroxy-2-naphthalenesulf-onic acid (J-acid), and 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (H-acid). They give two types of isomeric azo compounds depending on the pH-value of the... 

Dan et al. found that Brij-35 also produces an enhancement of the CL intensity of the reaction of fti.v AL[2-(A, -rnclhyl-2 -pyridiniumyl)ethyl]-AL [(trifluoromethyl)sulfonyl]]oxamide with hydrogen peroxide in the presence of some fluorophors [40], To be precise, the CL intensity increased by a factor of 130 for 8-aniline-1-naphthalenesulfonic acid (ANS) and 5.6 forrhodamine B (RH B), compared to the CL intensity in the absence of surfactant. This leads to an increase of 2-3 orders of magnitude in the linear dynamic ranges and a more precise determination of these analytes. However, improvement of the detection... 

An infinite ID complex [Ag( 14)( 15) with a single-stranded helical chain structure was obtained through the reaction of 6-amino-1-naphthalenesulfonic acid (H-14) and 2-methylpyrazine (15) with Ag2CC>3.58 Furthermore, when tetra- and hexaethyleneglycol-spaced ligands, 1,1 l-(3,6,9-trioxaundecane)diyl-bis(nicotinate) (16) and l,17-(3,6,9,12,15-pentaoxaheptadecane)diyl-bis(nicotinate) (17), were reacted with silver salts, double-stranded helical complexes (as exhibited in Fig. 11.24) were formed.59... 

It is relatively simple to determine the extent to which a sulfonation reaction has proceeded. The reaction mixture is neutralized with barium carbonate and treated with enough soda to form the sodium siplt. The number of sulfo groups present can be calculated from the amount of soda used up. One sulfo group requires 53 grams of NaaCOs. Calcium carbonate cannot be used for this purpose since calcium sulfate is soluble in solutions of naphthalenesulfonic acids. 

A reaction similar to the above involves the acylation of malonic ester through its magnesium enolate. Thus, the reaction of propionyl chloride with the ester enolate leads to diethyl propionylmalonate. Thermal decomposition of this compound with /3-naphthalenesulfonic acid yields ethyl propionylacetate (57%). This modification appears to be general in that it has been extended to the use of aliphatic, aromatic, and car-balkoxy acyl chlorides. ... 

From this time dye research in the German aniline dye industry flourished. Caro later described azo dye research and development as scientific mass production. The most important activity was the invention of key aryl amine intermediate compounds for use in the coupling reaction, and for this endeavor structural studies were essential. Caro extended the range of the new azo dyes into the reds with his invention of fast red AV (19) in July 1877. This was based on his reasoning that two naphthalene-based components in the azo compound would give a red. To achieve this he used diazotized 1-naphthionic acid (4-amino-1-naphthalenesulfonic acid) (20)37. 

This reaction is also applicable to 1,8-diamino-4-naphthalenesulfonic acid, t,8-diamino-3,6-naphthalenedisulfonic acid (24) and to the indo-phenol dyes of 1,8-naphthalenediamine with p-aminophenol and 4-amino-2,6-dichlorophenol. Owing to the liberation of hydrogen sulfide during the cyclization, the leuco-indophenol dyes of 2,3-dihydro-fH-periniidine-2-thione are obtained (25). 

The naphthylamine is treated with a four- to eight-fold excess of sodium hydrogen sulfite in an aqueous medium at 90-150° for 6-30 hours, the time required varying from case to case this affords the l,2,3,4-tetrahydro-4-oxo-2-naphthalenesulfonic acid which is stable in an acid or neutral medium but decomposes in alkali to sulfite and the naphthol 565 yields are almost quantitative. Moreover, 5-quinolinamine has been converted into 5-quinolinol by this route.566 The reaction fails, however, if there is a sulfo group in the meta-position to the amino group. 

Naphthalenesulfonic acid 124 Naphthalene, very finely ground (128 g), is added with stirring to sulfuric acid monohydrate (260 g) at 0°. To avoid sudden separation of the sulfonic acid from a supersaturated solution, a seed of the 1-sulfonic add is added after the naphthalene (the seed is obtained by warming a sample of naphthalene in sulfuric add on the water-bath and cooling the product). If the naphthalene has not all been sulfonated, naphthalene will separate when a sample of the reaction mixture is added to watery if that happens the reaction mixture should be warmed for a short time at 60°. 

In the naphthol series direct sulfonation is usually restricted to / -naphthols, since a-naphtholsulfonic acids are generally obtained in other ways, such as from naphthalene-di- and -tri-sulfonic acids in an alkali meii or from 1-amino-naphthalenesulfonic acids by the Bucherer reaction. 

Amines, polyamines, and aminophenols that can quinonize are similarly amenable to this reaction if an oxidizing agent is added 191 4-amino-3-hydroxy-1-naphthalenesulfonic acid was obtained from 1-naphthylamine,192 and a monosulfonic acid from / -phenylenediamine.193... 

When diazobenzene- or diazonaphthalene-sulfonic acid is treated analogously with sulfur dioxide in glacial acetic acid containing copper(i) chloride, the products are the disulfonic acids, owing to the instability of chlorosulfonyl sulphonic acids in aqueous solution.471 The reaction is a smooth one and yields are good. For example, 2-hydroxy-1,4-naphthalenedisulfonic acid was obtained in this way from 4-diazo-3-hydroxy-l-naphthalenesulfonic acid.472... 

The well-known dye intermediate 1,2,4-acid, or 4-amino-3-hydroxy-l-naphthalenesulfonic acid, is made by this general method from l-nitroso-2-naphthol. The reactions may be represented as follows ... 

Electrophilic aromatic substitution is the most traditional method for introducing functional groups into an aromatic ring. Lack of complete regioselectivity produces mixtures of compounds, however. Microwave irradiation has been used to modify and invert the selectivity of these reactions. In the sulfonation of naphthalene (24) under microwave irradiation, Stuerga [50] showed that the ratio of 1- and 2-naphthalenesulfonic acids (1- and 2-NSA, 25 and 26) obtained is a function of the applied power (Fig. 5.16). 

Swaab and Sutker [24] reported a modification of the foregoing procedure in which a solid, particulate, polysulfide polymer mixture is formed that is free flowing, insensitive to moisture, and redispersible in water to form a stable latex. The process involves the reaction of a Bimte salt (reaction product of sodium thiosulfate and bis(chloroethyl) ether with calcium sulfide in the presence of 5-30% of a dispersing agent [Mg(OH)2 or the sodium salt of a polyalkyl-naphthalenesulfonic acid]. 

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