Yellow (1,2)-di:hydro-pyrazine derivs. - used as clear yellow fluorescent dyes and organic intermediates

摘要

The novel 1,2- dihydropyrazine derivs. are of formula (I) (where Ar' and Ar2 are aromatic gps). The carboxamides of formula (II) and the 5:6-disubstd. 3-cyanopyrazine-2-carboxamides, of formula (III), used in the prepn. of (I) are also novel. Cpds. (I) are fluorescent and exhibit a green-yellow luminescence, and maybe used together with white pigments such as zinc oxide. Contrary to the cpd. of US. 3912724 and 3914276, (I) undergo no or very little colour change in the presence of direct sunlight. (II) are also useful as dyestuffs and as intermediates.