9-Dialkylamino-spiro {8 6H-{8 1{9 benzopyrano{8 3,2-g{9 quinoline-6,1{40 (3{40 H)-isobenzofuran{9 -3{40 -one compounds and pressure-sensitive recording system therewith

摘要

Disclosed are normally substantially colorless chromogenic 9-dialkylamino-spiro[6H-[1]benzopyrano[3,2-g]quinoline-6,1'(3'H)-isobe nzofuran]-3'-one color precursor compounds having the following structural formula: <IMAGE> wherein each R1 represents a lower alkyl group having from one to five carbon atoms and wherein each of R2 and R3 represents either a methyl group or a group which includes a methylene bridge resonance path having up to four carbon atoms, but wherein when R3 is a methylene bridge resonance path-containing group, R2 is not a methyl group. These compounds are initially substantially colorless but are capable of becoming highly colored when brought into reactive contact with many Lewis acid materials and the like. Accordingly, these compounds are highly useful as a component of pressure-sensitive copying papers.