Synthesis by reversed phase transfer catalysis and characterization of Naphthol AS-D pigment

Reversed phase transfer catalysis (rptc) was applied to synthesize the naphthol as-d pigment. this method consists in the transfer of the aryldiazonium cation 4-nitrobenzenediazonium from aqueous medium into the organic phase (nitrobenzene) in the form of a lipophilic ions pair by the catalyst used (perfluorooctyl potassium sulfonates). in the organic phase the azo-coupling reaction between 4-nitrobenzenediazonium chloride and 3-hydroxy-2-carboxylic acid 2-methyl-anilide (naphthol as-d) takes place as coupling component. using this unconventional method of synthesis,an increase of the reaction rate,combined with a higher purity of the product,was obtained. © 2013 eleonora cornelia crasmareanu et al.