Abstract:
Spirodipyrans based on 2-alkylarylpyrylium salts and 4dialkylaminobenzaldehydes, their manufacture and their use as dye precursors for pressure-sensitive recording materials.
Abstract:
Spiropyrans based on 1,2,3,4-tetrahydroquinoline compounds, a process for their manufacture and their use as dye-forming components in copying processes.