Copper Catalyst For N-arylation Reaction Of Bromamine Acid

Anthraquinone dye is a kind of very important dye, which is not only used in dyeing and printing industry but also used in medicine. N-arylation reaction of bromamine acid belonging to Ullman coupling reaction is applied to synthesize anthraquinone reactive dyes and anthraquinone acid dyes. Now cuprous chloride with copper power or copper(II) with metal reductant(Fe2+,Sn2+) are used in the N-arylation reaction of bromamine acid. Much copper catalyst and metal reductants used lead to environment pollution.In this paper, montmorillonite-supported copper(I) catalyst (Cu+-MMT) was investigated in the N-arylation reaction of bromamine acid. The catalyst was produced via reducing Cu2+-MMT which was prepared by a simple ion exchange method. The resulting catalyst was characterized by X-ray diffraction and other characterization with results showing that Cu2+and Cu+had been successfully intercalated into the interlayer of Montmorillonite. The coupling of bromamine acid with N-acetyl-1,3-phenylenediamine was chosen as the model reaction to optimize reaction conditions including copper source, copper amount, reductant, and reaction pH. The copper sulfate and L-sodium ascorbate were selected as the best candidate for copper source and reductant, respectively. Copper amount was5.5mol%and reaction pH ranged from8.5to8.8. The supported catalyst also promoted N-arylation reaction of bromamine acid with various substituted aromatic amines(40.5%-98.0%). The catalytic system could tolerate different functional groups such as-COOH,-OCH3,-SO3H,-OH,-CH3,-Cl.We designed seven simple ligands with nitrogen, oxygen and sulpher donors including: L-methionine(L1), PMDETA(L2), Salicylaldehyde ethanolamine Schiff base(L3), Salicylaldehyde o-animophenol Schiff base(L4), Salicylaldehyde2-aminothiophenol Schiff base(L5),4-aminoacetophenone thiosemicarbazide Schiff base(L6), L-cysteine(L7) and tested their effects in the N-arylation reaction of bromamine acid. PMDETA was chosen as the effective ligand with the yield of91.8%. After a series of coupling reactions of different amines with bromamine, yields of47.8%-88.6%were obtained.