Spirodipyrans useful as dye precursors for copying processes

摘要

New spirodipyrans of the formula (I) in which A is an optionally substituted benzene or naphthalene nucleus, B is dimethylene, trimethylene or tetramethylene substituted by from 1 to 3 alkyl groups and R1 and R2 are each alkyl of 1 to 6 carbon atoms, which may be substituted by cyano. The compounds (I) give deep blue to violet colorations with acid materials. They may be used for the manufacture of pressure-sensitive recording materials. The compounds (I) exhibit improved solubility in the solvents used for the manufacture of microcapsules.