Benzenesulfonic acid, 2-amino-5-nitro- → Sulfanilic acid

HRID 1742559

Reaction equation

HRID 1742559 reaction equation
N[C:2]1[CH:7]=[CH:6][C:5]([N+]([O-])=O)=[CH:4][C:3]=1[S:11]([OH:14])(=[O:13])=[O:12].OC1C2C(=C(S(O)(=O)=O)C([NH2:26])=CC=2)C=C(S(O)(=O)=O)C=1>O>[S:11]([OH:14])(=[O:13])([C:3]1[CH:4]=[CH:5][C:6]([NH2:26])=[CH:7][CH:2]=1)=[O:12]

Participants

4

Reactant 2

HCID 66786Benzenesulfonic acid, 2-amino-5-nitro-HCID 810242-Amino-5-hydroxynaphthalene-1,7-disulphonic acid

Product 1

HCID 8479Sulfanilic acid

Reagents, catalysts & solvents 1

HCID 962WaterSolvent2×

Procedure

2-Amino-5-nitro-benzenesulfonic acid is diazotized and coupled neutrally to I acid. 43 mmol of this dye are dissolved in 200 ml water and indirectly diazotized. After stirring for 1 hour, the excess nitrous acid is removed with amidosulfonic acid and a solution of 43 mmol 4-hy-droxy-7-aminonaphthalene-2,8-disulfonic acid in 200 ml water is added. Coupling is completed overnight at pH 8-9, the dye is filtered under suction and the sulfo group is split off by boiling for 12 h in a 1:1 mixture of water and N-methyl pyrrolidone containing 60 ml concentrated hydrochloric acid. This dye is diazdtized and added dropwise to a solution in 100 ml water of 7.2 mmol of a dye obtained by acidic coupling of p-sulfanilic acid onto 4-amino-5-hydroxynaphthalene-1,3-disulfonic acid. After stirring overnight, the dye is precipitated by addition of acetone, optionally dissolved and allowed to crystallize once more and then washed with aqueous acetone. 0.1 g dye are dissolved in 9.9 g polyvinyl alcohol (PVAL) (Mowiol®28-99, a product of Hoechst AG) and 190 ml water and a 500μ thick layer is cast from this solution. After evaporation of the water, an approx. 50μ thick dark-blue film is obtained. The film is stretched by 500% at 130° C. The value is 15.3 at 650 nm. If the following acids are used instead of 4-amino-5-hydroxynaphthalene-,1, 3-disulfonic acid, the following results are obtained:

Workup

  1. customthe excess nitrous acid is removed with amidosulfonic acid
  2. waitCoupling is completed overnight at pH 8-9
  3. filtrationthe dye is filtered under suction
  4. customthe sulfo group is split off
  5. additionby boiling for 12 h in a 1:1 mixture of water and N-methyl pyrrolidone containing 60 ml concentrated hydrochloric acid
  6. additionadded dropwise to a solution in 100 ml water of 7.2 mmol of a dye

Sources & evidence

ORD record
ord-2e2d477fe58d4aaeade4dc5cb0963f81
Source dataset
uspto-grants-1994_08
Patent number
US05340504

Linked notes

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