Carbazole dioxazine pigment and a method for its preparation

Abstract

The present disclosure provides carbazole-dioxazine pigment of Formula I; wherein, R is C1-C8 alkyl group, preferably R is an ethyl group, R1 is a chloro group, and R2 is a —NHC(═O)Ph group. The pigment is synthesized from 3-nitro-N-ethylcarbazole. The first step is nitration of 3-nitro-N-ethylcarbazole to form 3,6-dinitro-N-ethylcarbazole which is reduced to form 3-amino-6-nitro-N-ethylcarbazole. This amino compound is benzoylated to form 3-benzamido-6-nitro-N-ethylcarbazole which is then hydrogenated to form 6-amino-3-benzamido-N-ethylcarbazole. Condensation of 6-amino-3-benzamido-N-ethylcarbazole with chloranil provides an intermediate. Cyclization of the intermediate in the presence of a cyclization reagent provides the compound of Formula-I. The pigment has wavelength of maximum absorption (λmax) at 571 nm in dimethylformamide as a solvent.

Dependencies are inferred from the claim text.