A process for producing 2,5-diamino-6-nitropyridine derivatives having the general formula (I) ##STR1## wherein R.sup.1 to R.sup.4 represent hydrogen or the radicals alkyl, hydroxy alkyl, dihydroxy alkyl, alkoxy alkyl, alkoxy carbonyl, hydroxy- or chlorine-substituted alkoxy carbonyl, aminoalkyl and aminoalkyl substituted by alkyl or hydroxy alkyl groups, the alkyl groups in each case containing 1 to 4 carbon atoms or an oxazolidinone ring being formed by R.sup.1 and R.sup.2 and/or R.sup.3 and R.sup.4. The present invention also relates to novel 2,5-diamino-6-nitropyridine derivatives and to a hair dyeing agent containing 2,5-diamino-6-nitropyridine derivatives, which are direct nitro dyes coloring the hair yellow orange to blue violet and are physiologically harmless.
一种生产具有通式(I)的2,5-二
氨基-6-硝基
吡啶衍生物的方法
其中R.sup.1到R.sup.4代表氢或基团烷基、羟基烷基、二羟基烷基、烷氧基烷基、烷氧羰基、羟基或
氯取代的烷氧基羰基、
氨基烷基和由烷基或羟基烷基基团取代的
氨基烷基,每种情况下的烷基基团含有1至4个碳原子或由R.sup.1和R.sup.2以及/或R.sup.3和R.sup.4形成的
噁唑烷酮环。本发明还涉及新颖的2,5-二
氨基-6-硝基
吡啶衍生物以及含有2,5-二
氨基-6-硝基
吡啶衍生物的染发剂,这些直接硝基
染料可将头发染成黄橙色至蓝紫色,并且在生理上是无害的。