Manufacture of pyrazines

A process for the manufacture of pyrazines of the formula ##STR4## wherein the R.sup.1 's and R.sup.2 's may be identical or different and each is hydrogen or an alkyl of 1 to 10 carbon atoms, cyclopentyl, cyclohexyl, aralkyl of 7 to 12 carbon atoms, phenyl, naphthyl and furthermore each R.sup.1 and the adjacent R.sup.2 together with the two carbon atoms joining the two radicals may be members of an alicyclic ring of from 5 to 12 members, wherein the above radicals and rings can in addition be substituted by alkyl or alkoxy of 1 to 4 carbon atoms or nitro in which nitrooxiranes of the formula ##STR5## wherein R.sup.1 and R.sup.2 have the above meanings, are reacted with ammonia.