Color former mixture
AssigneeCiba Specialty Chemicals Corporation
InventorsRudolf Zink, Klaus Huber
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Abstract
The invention describes a color former mixture comprising (a) a compound of formula (1) and/or of formula (2) and/or of formula (3) and (b) a compound of formula (4), or a color former mixture comprising at least two compounds of component (b). The color former mixture is suitable for pressure- and particularly for heat-sensitive recording materials and has excellent storage ability and superior paper whiteness.
Claims2
A compound of formula ##STR25## wherein X' is C.sub.1 -C.sub.5 alkyl;
- or ##STR26## Y' is C.sub.4 -C.sub.5 alkyl;
- and R'.sub.11 is hydrogen or C.sub.1 -C.sub.5 alkyl.
A process for the preparation of a compound of formula (4'), which comprises condensing a benzophenone of formula ##STR27## with a phenol or phenol ether of formula ##STR28## in a temperature range from preferably 0-70.degree. C. in 50 to 100% sulfuric acid, with removal of the formyl protective group if present, to a phthalide of formula ##STR29## and then cyclising said phthalide of formula (III), in the temperature range from 20-100.degree. C., to a compound of formula (4'),
- wherein
- X' and Y' and R'.sub.11 have the meaning given in formula (4'), and
- R' is hydrogen or C.sub.1 -C.sub.4 alkyl.
Dependencies are inferred from the claim text.