Synthesis
Method of preparing pigment yellow 168, comprising the steps of:
(1) dissolving 2-nitro-4-sulfoaniline, in hydrochloric acid;
(2) the solution is cooled down to less than 5 degrees Celsius in an ice bath;
(3) sodium nitrite is added and stirred thoroughly to form a diazonium salt solution;
(4) mix sodium hydroxide solution, water and o-chloroacetoacetanilide and mix thoroughly, then add acetic acid solution and mix until the formation of suspended particles, keep mixing;
(5) adding the solution of step (3) to the solution of step (4) for coupling and stirring thoroughly, while cooling the mixture in an ice bath so that the temperature of the mixture is lower than 2 degrees Celsius;
(6) Calcium oxide is added and heated to 30 to 45 degrees Celsius; held for 20 minutes; and allowed to precipitate sufficiently as a colored precipitate
(7) Filtering, washing and drying to obtain pigment yellow 168; after grinding, said pigment yellow 168 powder is obtained.
References
[1] Pltner J, Dreuw A. Solid state fluorescence of Pigment Yellow 101 and derivatives: a conserved property of the individual molecules[J]. Physical Chemistry Chemical Physics, 2006, 8(10): 1197-1204.
