Abstract R-salt, the disodium salt of 2-naphthol-3,6-disulfonic acid, is isolated in pure form and high yield from sulfonation product mixtures resulting from the sulfonation of beta-naphthol and containing R-acid and isomers thereof, particularly G-acid, by a process comprising (1) dissolving the sulfonation product mixture in water to provide a water solution containing a defined concentration of R-salt, (2) reacting the solution with a defined proportion of aniline in the presence of a defined amount of sodium ions at a temperature of about 70*-90*C., (3) cooling the solution to form a precipitate of the tri-sodium monoaniline salt of the R-acid therein, (4) separating the precipitate from the solution, (5) reacting the precipitate, in the presence of water, with sodium hydroxide to convert the tri-sodium monoaniline salt of the R-acid to the di-sodium salt thereof, i.e., R-salt, (6) removing the free aniline formed in step 5 by steam distillation and (7) separating the R-salt of the water.
Inventors
👤 Martin Louis Feldman
👤 Donald William Hagedorn
👤 John Edson Gordon
Bibliographic Details
Application Number—
JurisdictionUS
Data Sourcegoogle_patents
Last Synchronized2026-11-09 09:51
CPC Classifications
C; C07; C07C; C07C309/00
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
216 words
A METHOD FOR OBTAINING THE DISODIUM SALT OF 2-NAPHTHOL3,6-DISULFONIC ACID FROM A SULFONATION MASS RESULTING FROM THE SULFONATION, OF BETANAPHTHOL WITH CONCENTRATED SULFURIC ACID AND COMPRISING 2-NAPHTHOL-3,6-DISULFONIC ACID AS THE PRINCIPAL SULFONATION PRODUCT, COMPRISING THE STEPS OF (1) DISSOLVING THE SULFONATION MASS IN WATER TO PROVIDE A WATER SOLUTION THERE CONTAINING FROM ABOUT 0.005 TO ABOUT 0.04 GRAM MOLES OF 2NAPHTHOL-3,6-DISULFONIC ACID PER 100 CC. OF SOLUTION (2) REACTING THE WATER SOLUTION AT ABOUT 70*-90*C. WITH FROM ABOUT 0.5 TO ABOUT 3 GRAM MOLES OF ANILINE PER GRAM MOLE OF 2-NAPHTHOL3.6-DISULFONIC ACID IN SAID SOLUTION IN THE PRESENCE OF A SUFFICIENT AMOUNT OF SODIUM HYDROXIDE OR A WATER-SOLUBLE SODIUM SALT SELECTED FROM SODIUM SULFATE, SODIUM CARBONATE AND SODIUM CHLORIDE TO PROVIDE FROM ABOUT 0.1 TO ABOUT 0.4 GRAM MOLES OF SODIUM IONS IN SAID SOLUTION, (3) COOLING THE SOLUTION TO A TEMPERATURE BELOW ABOUT 45*C. WHEREBY THE TRI-SODIUM MONO-ANILINE SALT OF THE 2-NAPHTHOL-3,6-DISULFONIC ACID IS FORMED AS A PRECIPITATE IN SAID SOLUTION, (4) SEPARATING THE PRECIPITATE FROM THE SOLUTION, (5) REACTING THE PRECIPITATE, IN THE PRESENCE OF WATER, WITH SOIDUM HYDROXIDE TO CONVERT THE TRI-SODIUM MONO-ANILINE SALT OF THE 2-NAPHTHOL-3,6-DISULFONIC ACID TO THE DI-SODIUM SALT, (6) REMOVING THE FREE ANILINE FORMED IN STEP 5 BY STEAM DISTILLATION AND (7) SEPARATING THE DI-SODIUM SALT FROM THE WATER.
Claim 2
Independent Claim
216 words
A METHOD FOR OBTAINING THE DISODIUM SALT OF 2-NAPHTHOL3,6-DISULFONIC ACID FROM A SULFONATION MASS RESULTING FROM THE SULFONATION, OF BETANAPHTHOL WITH CONCENTRATED SULFURIC ACID AND COMPRISING 2-NAPHTHOL-3,6-DISULFONIC ACID AS THE PRINCIPAL SULFONATION PRODUCT, COMPRISING THE STEPS OF (1) DISSOLVING THE SULFONATION MASS IN WATER TO PROVIDE A WATER SOLUTION THERE CONTAINING FROM ABOUT 0.005 TO ABOUT 0.04 GRAM MOLES OF 2NAPHTHOL-3,6-DISULFONIC ACID PER 100 CC. OF SOLUTION (2) REACTING THE WATER SOLUTION AT ABOUT 70*-90*C. WITH FROM ABOUT 0.5 TO ABOUT 3 GRAM MOLES OF ANILINE PER GRAM MOLE OF 2-NAPHTHOL3.6-DISULFONIC ACID IN SAID SOLUTION IN THE PRESENCE OF A SUFFICIENT AMOUNT OF SODIUM HYDROXIDE OR A WATER-SOLUBLE SODIUM SALT SELECTED FROM SODIUM SULFATE, SODIUM CARBONATE AND SODIUM CHLORIDE TO PROVIDE FROM ABOUT 0.1 TO ABOUT 0.4 GRAM MOLES OF SODIUM IONS IN SAID SOLUTION, (3) COOLING THE SOLUTION TO A TEMPERATURE BELOW ABOUT 45*C. WHEREBY THE TRI-SODIUM MONO-ANILINE SALT OF THE 2-NAPHTHOL-3,6-DISULFONIC ACID IS FORMED AS A PRECIPITATE IN SAID SOLUTION, (4) SEPARATING THE PRECIPITATE FROM THE SOLUTION, (5) REACTING THE PRECIPITATE, IN THE PRESENCE OF WATER, WITH SOIDUM HYDROXIDE TO CONVERT THE TRI-SODIUM MONO-ANILINE SALT OF THE 2-NAPHTHOL-3,6-DISULFONIC ACID TO THE DI-SODIUM SALT, (6) REMOVING THE FREE ANILINE FORMED IN STEP 5 BY STEAM DISTILLATION AND (7) SEPARATING THE DI-SODIUM SALT FROM THE WATER.