La rèaction de parri et les sulfonamides

In der Parri's reaction certain sulphonamidcs give colourations which may lead to confusion with barbiturates. Sulphathiazole gives an intense violet colour; sulpliapyndine and sulphadiazinc give a weak violet colour.In the case of sulphathiazolc the colour is due to its coball(II) salt. In the presence of an excess of ammonia there is formed an insoluble rose-coloured product corresponding to the formula (Sulphathiazole) ₂Co(NH₃).3H₂O.