Fluorescent yellow 1,2,3,4-Tetrachloro-11H-Isoindolo-2,1-A!-Benzimidazol-11-one pigments
AssigneeCiba Specialty Chemicals Corporation
InventorsEdward E. Jaffe, Martin Tanner
Life of this patent
Estimating the term…
Abstract
Fluorescent yellow pigments comprising 1,2,3,4-tetrachloro-11H-isoindolo-2,1-a!-benzimidazol-11-one and various derivatives thereof; the use of said pigments in a variety of substrates such as alkyds, enamels, inks and the like; a process for the preparation thereof involving the condensation of the appropriate o-phenylenediamine and tetrachlorophthalic anhydride; and the aforementioned novel derivatives of said compound.
Claims10
A process for preparing compounds of the formula ##STR4## wherein R.sub.1 and R.sub.2 are independently hydrogen, halogen, C.sub.1 -C.sub.5 alkyl or C.sub.1 -C.sub.3 alkoxy, which comprises reacting tetrachlorophthalic anhydride with a compound of the formula ##STR5## wherein R.sub.1 and R.sub.2 are defined as above, at elevated temperatures in the presence of an arene sulfonic acid catalyst and a solvent selected from the group consisting of dichlorobenzene, toluene and xylene and recovering said compound.
Dependencies are inferred from the claim text.