| abstract |
Spirodipyrans of the formula <IMAGE> where A is the radical of a fused benzene ring or 2,1-naphthalene ring, the rings being unsubstituted or substituted by alkyl, alkoxy, nitro, chlorine, bromine or carbalkoxy, R1 is alkyl, phenyl, substituted alkyl or phenalkyl and R2 is hydrogen, or R1 and R2 together are trimethylene which is unsubstituted or substituted by 1, 2 or 3 alkyl and B is N-morpholinyl, substituted morpholinyl, thiomorpholinyl-S-dioxide, N-(N'-alkyl)-piperazinyl or N-isoindolinyl, AND PRESSURE-SENSITIVE RECORDING MATERIALS CONTAINING THESE SPIRODIPYRANS AS DYE-FORMING COMPONENTS. |