Patent ID: 11932594
Assignee: KING FAISAL UNIVERSITY
Field: Organic fine chemistry (Chemistry)
Classification: CPC C  A | IPC A  C

Claim 2:
3. A method of making the 8-((2-hydroxy-5-methylphenyl)diazenyl)naphthalene-1,3-disulfonic acid compound of claim 1, the method comprising:
adding a cooled solution of sodium nitrite in water to a cooled solution of 8-aminonaphthalene-1,3-disulfonic acid and hydrochloric acid with stirring to obtain a cooled diazonium salt solution;
adding the cooled diazonium salt solution to a cooled solution of p-cresol in sodium hydroxide to obtain an azo dye precipitate;
filtering and recrystalling the azo dye precipitate using ethanol; and
obtaining the 8-((2-hydroxy-5-methylphenyl)diazenyl)naphthalene-1,3-disulfonic acid compound.