Verfahren zur Herstellung von 2-(2'-Pyrazinyl)-benzimidazol und seinen Salzen

The invention comprises 2-(21-pyrazinyl)-benzimidazole of formula and acid addition salts thereof with inorganic and organic acids. It may be prepared by heating o-phenylenediamine with 2-pyrazine-carboxylic acid or a reactive derivative thereof (e.g. amide, nitrile, ester or iminoether hydrohalide) in polyphosphoric acid or by reacting N - (o - nitrophenyl) - 2 - pyrazinecarboxamide with a reducing agent such as zinc in HCl or acetic acid or hydrogen in the presence of a nickel, platinum or palladium catalyst. The products are chelating agents, e.g. for copper ions. Alkali metal salts may also be obtained. N - (o - Nitrophenyl) - 2 - pyrazinecarboxamide is prepared from 2-pyrazinecarboxylic acid chloride and o-nitroaniline. The compounds of the invention have anthelmintic acitivity and may be administered orally, e.g. in feed supplements.