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| | 2-Aminonaphthalene-1-sulfonic acid Basic information |
| | 2-Aminonaphthalene-1-sulfonic acid Chemical Properties |
| | 2-Aminonaphthalene-1-sulfonic acid Usage And Synthesis |
| Chemical Properties | Grey white to light pink powder. 2-Aminonaphthalene-1-sulfonic acid [81-16-3]. Tobias acid, C10H9NO3S, Mr 223.24, is sparingly soluble in water but the sodium salt is readily soluble. Coupling with diazo compounds takes place in the 1-position with elimination of the sulfonic acid group. | | Uses | Azo dye intermediate, optical brighteners. Sulfonation with oleum gives 2-aminonaphthalene-1,5-disulfonic acid, which can be desulfonated to produce 2-aminonaphthalene-5- sulfonic acid. Tobias acid is used as a diazo component in acid dyes (e.g., C.I. Acid Yellow 19), red reactive dyes, and pigments such as the important Lithol Reds, [e.g., C.I. Pigment Red 49]. The free acid of C.I. Pigment Red 49 is also remarkably insoluble and can be used as a pigment. | | Uses | 2-Amino-1-naphthalenesulfonic acid has been used in the preparation of 2-(2-naphthylamino)benzoxazole by reacting with 2-chlorobenzoxazole. | | Production Methods | 2-Hydroxynaphthalene-1-sulfonic acid is heated with a mixture of ammonia and ammonium sulfite in an autoclave at 150 ℃ and 1 MPa for 30 h. The reaction mixture is added to a slurry of lime, and excess ammonia is driven off. Inorganic calcium salts are filtered off at 80℃, and the filtrate is acidified with hydrochloric acid at 40℃ to precipitate Tobias acid in 95 % yield. Care must be taken throughout the process to avoid desulfonation and formation of 2- naphthylamine. | | General Description | 2-Amino-1-naphthalenesulfonic acid is a manufacturing intermediate in the monosulfo monoazo color additive D&C Red No. 34 and its lakes. | | Purification Methods | Crystallise the acid under nitrogen from boiling water and dry it in a steam oven [Bryson Trans Faraday Soc 47 522, 527 1951]. [Beilstein 14 III 2240, 14 IV 2792.] |
| | 2-Aminonaphthalene-1-sulfonic acid Preparation Products And Raw materials |
| Raw materials | Sodium hydroxide-->Hydrochloric acid-->Sulfuric acid-->Ammonia-->Chlorosulfonic acid-->Sulfur dioxide-->2-Naphthol-->2-Ethylnitrobenzene-->1,2,3-Triazine, 4,5,6-trifluoro--->2-HYDROXY-1-NAPHTHALENESULFONIC ACID-->1-Amino-8-hydroxynaphthalene-3,6-disulphonic acid | | Preparation Products | J acid-->Lithol Red-->sodium 2-[(2-hydroxynaphthyl)azo]naphthalenesulphonate-->3-Hydroxy-N-2-naphthyl-2-naphthamide-->ReactivebrilliantredKE-7B-->disodium 2-[[1-(2,5-dichloro-4-sulphonatophenyl)-4,5-dihydro-3-methyl-5-oxo-1H-pyrazol-4-yl]azo]naphthalene-1-sulphonate-->REACTIVE RED 195-->2-Amino-1,5-naphthalenedisulfonic acid-->6-AMINO-1-NAPHTHOL-->1,2-DICHLORONAPHTHALENE-->2-Naphthylamine-->6-Amino-1-naphthalenesulfonic acid-->2-Aminotoluene-5-sulfonic acid-->disodium 2-[[1-(2-chloro-5-sulphonatophenyl)-4,5-dihydro-3-methyl-5-oxo-1H-pyrazol-4-yl]azo]naphthalene-1-sulphonate-->ACID YELLOW 19 |
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