The colour reaction of amiloride hydrochloride ph. eur.

Article abstract of DOI:10.3797/scipharm.aut-01-199

The reaction of amiloride hydrochloride (1.HCI) with bromine in alkaline solution generated a yellow-brown dehydrogenation product, which turned out as 3-(3-amino-1,2,4-oxadiazol-5-yl)-5-chloro-2,6-pyrazinediamine (2). The structure was deduced from the MS and the NMR spectra of 2 with the help of comparisons with corresponding spectra of amiloride (1) and reference substances 3 - 5. The agreement of all relevant data of the product and of authentical oxadiazolylpyrazine 2 as well as the accomplished X-ray analysis confirmed the postulated structure. The mechanism of the formation of 2 is also discussed.