Naphthalenes Naphthalenesulfonic acid

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. 

Naphthalenesulfonic acids are important chemical precursors for dye intermediates, wetting agents and dispersants, naphthols, and air-entrainment agents for concrete. The production of many intermediates used for making a2o, a2oic, and triphenylmethane dyes (qv) involves naphthalene sulfonation and one or more unit operations, eg, caustic fusion, nitration, reduction, or amination. 

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. 

Fig. 1. Selected paths to naphthalenesulfonic acids where N = naphthalene, SA = sulfonic acid, and yld = yield.

The older methods have been replaced by methods which require less, if any, excess sulfuric acid. For example, sulfonation of naphthalene can be carried out in tetrachloroethane solution with the stoichiometric amount of sulfur trioxide at no greater than 30°C, followed by separation of the precipitated l-naphthalenesulfonic acid the filtrate can be reused as the solvent for the next batch (14). The purification of 1-naphthalenesulfonic acid by extraction or washing the cake with 2,6-dimethyl-4-heptanone (diisobutyl ketone) or a C-1—4 alcohol has been described (15,16). The selective insoluble salt formation of 1-naphthalenesulfonic acid in the sulfonation mixture with 2,3-dimethyl aniline has been patented (17). 

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,... 

Naphthalenesulfonic Acid—Formaldehyde Condensates. The sodium salts of the condensation products of naphthalenesulfonic acid with formaldehyde constitute an important class of compounds which are mainly used in the area of concrete additives (32,33), agricultural formulations, mbber formulations, and synthetic tanning agents. They are also used in photographic materials (34). Hampshire Chemical Co. and Henkel of America, Inc., are the largest suppHers of naphthalene sulfonate in concrete additives (superplasticizer) and reportedly hold 75—80% of this market. It was estimated that naphthalene sulfonate demand from U.S. producers would reach approximately... 

Kuhm AE, A Stolz, K-L Ngai, H-J Knackmuss (1991) Purification and characterization of a 1,2-dihydroxy-naphthalene dioxygenase from a bacterium that degrades naphthalenesulfonic acids. J Bacteriol 173 3795-3802. 

A munber of organic compounds are suitable for use as tracers in a process for monitoring the flow of subterranean fluids. The following traces have been proposed benzene tetracarboxylic acid, methylbenzoic acid, naphthalenesulfonic acid, naphthalenedisulfonic acid, naphthalene-trisulfonic acid, alkyl benzene sulfonic acid, alkyl toluene sulfonic acid, alkyl xylene sulfonic acid, a-olefin sulfonic acid, salts of the foregoing acids, naphthalenediol, aniline, substituted aniline, pyridine, substituted pyridines [883]. 

Problem 11.18 Account for (a) formation of the a-isomer in nitration and halogenation of naphthalene, (f>) formation of a-naphthalenesulfonic acid at 80°C and -naphthalcnesulfonic acid at 160°C. -4... 

Probtem 18.63 Synthesize from naphthalene and any other reagents (a) naphthionic acid (4-amino-l-naphthalenesulfonic acid), (b) 4-amino-l-naphthol, (c) 1,3-dinitronaphthalene, (d) 1,4-diaminonaphthalene, (e) 1,2-dinitronaphthalene. Do not repeat the synthesis of any compound. ... 

A particularly important class of coupling components are the aminohydroxy-naphthalenesulfonic acids. Appropriate variation of the disazo component permits the development of shades ranging from orange to black. Orange and scarlet are achieved with I-acid (6-amino-l-hydroxy-naphthalene-3-sulfonic acid) and y-acid (7-amino-1-hydroxynaphthaIcne-3-sulfonic acid), whereas H-acid (8-amino-l-hydroxynaphthalene-3,6-disulfonic acid) and K-acid (8-amino-l-hydroxy-naphthalene-3,5-disulfonic acid) derivatives are useful for red to bluish-red hues. Extremely lightfast red shades are also accessible with disazo dyes ( brown dyes ). For chemical structures see Section 3.1.5). 

Sunset Yellow occurs as a brown-orange powder or granules. It is principally the disodium salt of 6-hydroxy-5-[(4-sulfophenyl)azo]-2-naphthalenesulfonic acid. The trisodium salt of 3-hydroxy-4-[(4-sulfophenyl)azo]-2,7-naphthalene-disulfonicacid may be added in small amounts. It dissolves in water to give a solution yellow-orange at neutrality or in acid and red-brown in base. When dissolved in concentrated sulfuric acid, it yields an orange solution that turns yellow when diluted with water. It is insoluble in ethanol. 

Sulfonation of naphthalene at 80 yields chiefly 1-naphthalenesulfonic acid sulfonation at 160° or higher yields chiefly 2-naphthalenesulfonic acid. When 1-naphthalenesulfonic acid is heated in sulfuric acid at 160°, it is largely converted into the 2-isomer. These facts become understandable when we recall that sulfonation is readily reversible (Sec. 11.12). 

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. 

An example of the interesting sensitivity of sulfonation processes to temperature changes is the well-known sulfonation of naphthalene. At temperatures below 80°, -naphthalenesulfonic acid is formed. At 160 to 165°, the /1-isomer is produced either by direct sulfonation or by heating the a-isomcr with sulfuric acid ... 

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