2-Naphthol-8-sulfonic acid, sodium salt

Bailey et al. (199) and Singh (200) used ion-exchange HPLC for the separation of amaranth from the intermediates naphthionic acid and R-salt, as well as the side reaction products 2-naph-thol-6-sulfonic acid sodium salt (Schaeffer s salt), 2-naphthol-6,8-disulfonic acid disodium salt (G-salt), and 2-naphthol-3,6,8-trisulfonic acid trisodium salt (NTSA). 

Diazo-l-naphthol-S-sulfonic acid, sodium salt... 

Naphthol Yellow S (citronin A, flavianic acid sodium salt, 8-hydroxy-5,7-dinitro-2-naphthalene sulfonic acid disodium salt) [846-70-8] M 358.2, m dec on heating. Greenish yellow powder soluble in H2O. The free sulfonic acid can be recrystd from dil HCl (m 150°) or AcOH-EtOAc (m 148-149.5°). The disodium salt is then obtained by dissolving the acid in two equivalents of aqueous NaOH... 

Occasionally, however, direct sulfonation is applied also to ot-naphthol for instance, 4-hydroxy-l,3-naphthalenedisulfonic acid is obtained as acid sodium salt in 95% yield by means of sulfuric acid at 50° for 2 hours148 or of sulfuric acid monohydrate at 20° for 36-48 hours and then at 40° for a day.149b... 

Naphthalenedisulfonic acid, 4-((4-anilino-5-sulfo-1-naphthyl) azo)-5-hydroxy-, trisodium salt 1-Naphthol-3,6-disulfonic acid-8-azo-4 -[N-phenyl-1 -naphthylamine]-8 -sulfonic acid trisodium salt Sodium anazolene Trisodium 4 -anilino-8-hydroxy-1,1 -azonaphthalene-3,6,5 -trisulfonate... 

Sulfonamide. See Sulfanilamide 1 -(4-Sulfo-1 -naphthylazo)-2-naphthol-3,6-disulfonic acid trisodium salt. See Amaranth 1 -(4-Sulfo-1 -naphthylazo)-2-naphthol-6,8-disulfonic acid, trisodium salt. See Acid red 18 2-(4-Sulfo-1 -naphthylazo)-1 -naphthol-4-sulfonic acid, disodium salt. SeeAcidred14 Sul-fon-ate AA-9, Sul-fon-ate LA-10. See Sodium dodecylbenzenesulfonate Sul-fon-ate OE-450. See Sodium oleic sulfonate Sulfonated Castor Oil 75%. See Sodium castor oil sulfate... 

Sulfotex WAT. See TEA-lauryl sulfate Sulfourea. See Thiourea Sulfoxyl. See Piperonyl sulfoxide 2-(6-Sulfo-2,4-xylylazo)-1-naphthol-4-sulfonic acid, disodium salt. See FD C Red No. 4 Su If ram in 1230-, Sulframin 1255. See Sodium dodecylbenzenesulfonate Sulframin AOS 38. See Sodium C14-16 olefin sulfonate... 

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. 

Llthol Reds. Lithol Red or Pigment Red 49 1/7103-38-4] is one of the most important of the precipitated salt pigments. They comprise a family of sodium (PR 49), barium (PR 49 1), calcium (PR 49 2), and strontium (PR 49 3) salts of dia2oti2ed Tobias acid or 2-naphthylamine-l-sulfonic acid coupled with 2-naphthol. The most popular are the barium and calcium salts, the former being yellower in shade. These reds are used where brightness, bleed resistance, and low cost ate of primary importance. They are neither resistant to heat nor chemicals, and are used primarily in printing inks and some inexpensive air-dried industrial paints where good durabiUty is not requited. 

Schaeffer s salt orgchem HOC oS03Na A light-yellow to pink, water-soluble powder the sodium salt formed from 2-naphthol-6-sulfonic acid used as an intermediate in synthesis of organic compounds. sha-forz, s6lt ... 

Hydroxy Naphthol Blue The disodium salt of l-(2-naph-tholazo-3,6-disulfonic acid)-2-naphthol-4-sulfonic acid deposited on crystals of sodium chloride. Small blue crystals, freely soluble in water. In the pH range between 12 and 13, its solution is red-pink in the presence of calcium ion and deep blue in the presence of excess disodium EDTA. 

In practice, the neutral or slightly acid solution of the sodium salts, containing little or no sodium chloride, is evaporated to a definite volume which depends on the composition of the reaction mixture and which is selected so that on cooling only the sodium 2-naphthol-6-sulfonate crystallizes out, but this as completely as possible. The precipitate is removed, and, to the filtrate, usually after further evaporation, is added enough salt to make it an 18 to 20 per cent salt solution. R salt then precipitates when the solution is cooled. Potassium chloride is then added to the mother liquor to precipitate the potassium salt of G acid. 

The nitrobenzene solution, together with the suspended solid material, is shaken with a mixture of 300 cc. water and 100 grams of ice, then twice with 100-cc. portions of cold water. The combined aqueous extracts are filtered through a moistened paper and then saturated with 200 grams of salt, whereupon sodium 2-naphthol-l-sulfonate is precipitated in colorless plates. Stirring is continued until all of the salt is dissolved, and the mixture is allowed to stand overnight, then filtered. The product is pressed out and washed twice with saturated salt solution. The filter cake is used directly for the preparation of 2-naphthyl-amine-l-sulfonic acid after tests have shown that it does not fluoresce in soda solution and does not yield a water soluble, orange red dye with diazotized aniline and thus does not contain isomeric naphtholsul-fonic acids. 

Phenols may be obtained by fusing the corresponding sulfonic acid with sodium or potassium hydroxide or by the hydrolysis of diazonium salts (see below). Both 1- and 2-naphthol may be obtained from the corresponding sulfonic acids. 

Incompatibilities poorly compatible with citric acid, saccharose solutions, and saturated sodium bicarbonate solutions. Incompatible with ascorbic acid, gelatin, and glucose. Method of manufacture diazotized sulfanilic acid is coupled with Schaeffer s salt (sodium salt of (3-naphthol-6-sulfonic acid). 

Schaeffer s salt. (sodium salt of 2-naphthol-6-sulfonic acid). C10H6OHSO3Na. 

Derivation Sulfonation of (i-naphthol with chloro-sulfonic acid in nitrobenzene at OC followed by heating the resulting 1-sulfonic acid with ammonium hydrogen sulfite and ammonia at 145-150C. Purification is by precipitation from dilute solution of the sodium salt. 

Sodium salt of l-naphthol-4-sulfonic add (Ka = 6.3 X 10 ). Acid form colorless alkaline form fluoresces. Approximate interval, from pH 7.0 "(12.7% fluorescence) to 9.6 (93.1% fluorescence). 

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