7H-pyrazolo[5, 1-a]benz[d,e]isoquinolin-7-ones: Yellow to orange dyes for synthetic-polymer fibres

N-Amino-1,8-naphthalimides were condensed with ketones containing an α-methylene group and the resulting hydrazones ring closed to afford derivatives of 7H-pyrazolo(5,1-a)benz(d,e)isoquinolin-7-one. These compounds coloured synthetic-polymer fibres, particularly polyester, in brilliant fluorescent greenish-yellow to orange hues of good fastness to light and sublimation. The colour of the dyes is discussed with respect to substituent effects in the pyrazole and naphthalene rings, and in relation to analogous 7H-benzimidazo(2,1-a)benz(d,e)isoquinolin-7-ones.