Process for the manufacture of nitroaminopyridines

Claim 1

A process for the manufacture of 2,4,6-triamino-5-nitro-pyridines of the general formula ##STR43## wherein R 1 , R 2 , R 3 , R 4 , R 5 and R 6 independently represents hydrogen; alkyl of 1 to 10 carbon atoms which are unsubstituted or substituted by hydroxy, carboxy, C 2 -C 10 carbalkoxy, C 1 -C 8 -alkoxy, phenoxy, pyrrolidonyl or C 1 -C 10 acyloxy; phenyl which is unsubstituted or substituted by halo, lower alkyl, lower alkoxy, β-hydroxyethyl, cyano, C 1 -C 5 alkanoylamino or lower carboalkoxy; benzyl; phenethyl; cycloalkyl; a group of the formula CH.sub.2 CH.sub.2 SO.sub.3 H, CH.sub.2 CH.sub.2 OSO.sub.3 H, (CH.sub.2).sub.3 OSO.sub.3 H, ##STR44## (CH.sub.2).sub.4 OSO.sub.3 H, (CH.sub.2).sub.6 OSO.sub.3 H, ##STR45## (CH.sub.2).sub.2 O(CH.sub.2).sub.2 OSO.sub.3 H, (CH.sub.2).sub.3 O(CH.sub.2).sub.2 OSO.sub.3 H, (CH.sub.2).sub.3 O(CH.sub.2).sub.4 OSO.sub.3 H, (CH.sub.2).sub.3 OC.sub.2 H.sub.4 OCH.sub.2 C.sub.6 H.sub.4 SO.sub.3 H, (CH.sub.2).sub.3 OC.sub.2 H.sub.4 OC.sub.2 H.sub.4 C.sub.6 H.sub.4 SO.sub.3 H, (CH.sub.2).sub.3 OC.sub.2 H.sub.4 OC.sub.6 H.sub.4 SO.sub.3 H, CH.sub.2 CH.sub.2 OC.sub.6 H.sub.4 SO.sub.3 H, (CH.sub.2).sub.3 OC.sub.6 H.sub.4 SO.sub.3 H, (CH.sub.2).sub.3 OCH.sub.2 C.sub.6 H.sub.4 SO.sub.3 H, ##STR46## a group of the formula --R.sub.5 '--Q wherein --R.sub.5 '-- is a group of the formula ##STR47## a is an interger from 1 to 12 and wherein Q is a group of the formula ##STR48## where R.sub.1 ' and R.sub.2 ' are hydrogen, C.sub.1 -C.sub.4 alkyl, benzyl or cyclohexyl, R 3 ' is hydrogen, C 1 -C 4 alkyl, benzyl, cyclohexyl, alkoxy or amino; or R 1 ', r 2 ' and R 3 ' are, together with the nitrogen to which they are attached, pyridyl, n is 1 or 2, and the anion X - is chloride, bromide, iodide, nitrate, hydrogen sulphate, phosphate, benzenesulphonate, (nitro, chloro, bromo, C 1 -C 4 -alkyl or C 1 -C 4 -alkoxy)-benzenesulphonate, C 1 -C 4 alkylsulphonate, or C 1 -C 4 alkylsulphate; or the double salt thereof with zinc or cadmium halide; or R 1 and R 2 , R 3 and R 4 or R 5 and R 6 together with the nitrogen to which they are attached independently represent pyrrolidino, piperidino, piperazino, N-lower alkylpiperazino, (N-formyl- or N-lower alkylcarbonyl)-piperazino or morpholino; which process comprises nitrating the corresponding 2-bromo-3-cyano-4,6-diamino pyridine with a mixture of nitric acid and sulphuric acid at -20° to +40° C to form the corresponding 2-bromo-3-cyano-4,6-diamino-5-nitro pyridine, aminating said 2-bromo-3-cyano-4,6-diamino-5-nitro pyridine with an amine of the formula HNR 5 R 6 at a temperature of 30° to 200° C to form the corresponding 3-cyano-2,4,6-triamino-5-nitro pyridine, and saponifying the resultant 3-cyano-2,4,6-triamino-5-nitro pyridine with concentrated sulphuric acid at a temperature of 90° to 150° C until decarboxylation is effected.