What mechanism is involved in the Philips condensation reaction?

The condensation mechanism is involved in the Phillips condensation reaction. The benefit of this method is that the benzimidazoles are easily acquired using diluted acid at a lower temperature.

The Phillips reaction involves condensing ortho phenylenediamines with organic acids in presence of diluted mineral acids to create benzimidazoles. Amines are allowed to react with acids to form amides. The amine reacts with acid and creates an amide. To do this, one of the amine group is acylated with the organic acid in presence of mineral acid to create an N-acylated compound. Then the other nitrogen creates a bond with the carbonyl carbon of the first acyl group, which closes the ring.