1
Patricia Dwyer Hallquist, William J Becker, Robert E Miller, Kenneth D Glanz: Fluoran derivatives and their use in recording materials. Appleton Papers, Paul S Phillips Jr, Benjamin Mieliulis, June 6, 1989: US04837210 (4 worldwide citation)

The invention relates to novel fluoran compounds of the general formula ##STR1## wherein R.sub.1 and R.sub.2, each independently of the other, are lower alkyl;


2
Patricia Dwyer Hallquist, William J Becker, Robert E Miller, Kenneth D Glanz: Fluoran derivatives and their use in recording materials. Appleton Papers, Paul S Phillips Jr, Benjamin Mieliulis, March 20, 1990: US04910183 (3 worldwide citation)

The invention relates to novel fluoran compounds of the general formula ##STR1## wherein R.sub.1 and R.sub.2, each independently of the other, are lower alkyl;


3
Dwyer Hallquist Patricia, Becker William J, Miller Robert E, Glanz Kenneth D: Derives de fluorane et utilisation de ces derives dans les materiaux denregistrement, Fluoran derivatives and their use in recording materials. Appleton Papers, SMART & BIGGAR, December 24, 1991: CA1293506

AbstractThe invention relates to novel fluoran compounds of the general formula Imagewherein R1 and R2, each independently of the other, are lower alkyl;or a pyrrolidinyl, piperidino, morpholino orA is Image piperazino radical; andR3 and R4, each independently of the other, are C1-C12 alkyl,cycloalk ...