Preparation of Pigment Red 149
The invention provides a process for preparing N,N′-di(3′,5′-dimethylphenyl)perylene bis(dicarboximide), and other pigments having modified properties, by reaction of perylene-3,4,9,10-tetracarboxylic dianhydride with 3,5-dimethylaniline, or a mixture of 3,5-dimethyl aniline and at least one other primary amine, in the presence of a secondary amine or tertiary amine as catalyst, wherein the reaction occurs in an aqueous reaction medium and in the presence of added seed crystals of N,N′-di(3′,5′-dimethylphenyl) perylenebis(dicarboximide), such that the aqueous medium is present at the beginning of the reaction.
1. A process for preparing N,N′-di(3′,5′-dimethyl phenyl)perylenebis(dicarboximide), the process comprising reacting perylene-3,4,9,10-tetra carboxylic dianhydride with 3,5-dimethylaniline in the presence of a secondary amine as catalyst, wherein:
a molar ratio between the 3,5-dimethylaniline and the perylene-3,4,9,10-tetracarboxylic dianhydride ranges from 2:1 to 3:1;
the reaction occurs in an aqueous reaction medium and in the presence of added seed crystals of N,N′-di(3′,5′-dimethylphenyl) perylenebis(dicarboximide), wherein the seed crystals are present prior to the beginning of the reaction;
the aqueous reaction medium is present at the beginning of the reaction;
the reaction occurs at a temperature in the range from 130° C. to 170° C. and at a pressure in the range from 2 bar to 13 bar; and
the process provides Pigment Red 149 in the alpha form, such that the Pigment Red 149 comprises less than 5% by weight of a monoimide by-product.
2. The process according to claim 1 , wherein the aqueous reaction medium comprises no further organic solvents.
3. The process according to claim 1 , wherein the secondary amine is selected from the group consisting of piperazine, N-(2-hydroxyethyl) piperazine, diethanolamine, N-ethylpiperazine, N-methylcyclohexylamine, imidazole and N-methylimidazole.
4. The process according to claim 1 , wherein the seed crystals are obtained from at least one preceding charge.
5. The process according to claim 1 , wherein aqueous reaction medium remaining after a reaction product is filtered off is reused in the preparation of a subsequent charge.
6. The process according to claim 1 , wherein 0.5 to 2.0 mol of the secondary amine are used per mole of the perylene-3,4,9,10-dicarboxylic dianhydride.
7. A process for preparing a perylenebis(dicarboximide), the process comprising reacting perylene-3,4,9,10-tetracarboxylic dianhydride with a primary amine mixture in the presence of a secondary amine as catalyst, wherein the reaction occurs in an aqueous reaction medium and in the presence of added seed crystals of N,N′-di(3′,5′-dimethylphenyl) perylenebis-(dicarboximide), wherein the seed crystals are present prior to the beginning of the reaction,
wherein:
the aqueous reaction medium is present at the beginning of the reaction;
the primary amine mixture comprises 3,5-dimethylaniline and 0% to 10% by weight of a primary amine, based on a total weight of the primary amine mixture;
the reaction occurs at a temperature in the range from 130° C. to 170° C. and at a pressure in the range from 2 bar to 13 bar; and
a molar ratio between the 3,5-dimethylaniline and the perylene-3,4,9,10-tetracarboxylic dianhydride ranges from 2:1 to 3:1.
8. The process according to claim 1 , further comprising converting the N,N′-di(3′,5′-imethylphenyl)perylenebis(dicarboximide) into particles having an average size <0.2 μm by at least one of dry and wet grinding, optionally with subsequent recrystallization from a solvent.
9. The process according to claim 7 , wherein the aqueous reaction medium comprises no further organic solvents.
10. The process according to claim 7 , wherein aqueous reaction medium remaining after a reaction product is filtered off is reused in the preparation of a subsequent charge.
11. A process for preparing a perylenebis(dicarboximide), the process comprising reacting perylene-3,4,9,10-tetracarboxylic dianhydride with a primary amine mixture in the presence of a tertiary amine, wherein:
the reaction occurs in an aqueous reaction medium and in the presence of added seed crystals of N,N′-di(3′,5′-dimethylphenyl) perylenebis(dicarboximide), wherein the seed crystals are present prior to the beginning of the reaction;
the aqueous reaction medium is present at the beginning of the reaction;
the primary amine mixture comprises 3,5-dimethylaniline and 0% to 10% by weight of a primary amine, based on a total weight of the primary amine mixture;
the reaction occurs at a temperature in the range from 130° C. to 170° C. and at a pressure in the range from 2 bar to 13 bar; and
a molar ratio between the 3,5-dimethylaniline and the perylene-3,4,9,10-tetracarboxylic dianhydride ranges from 2:1 to 3:1.
12. The process of claim 7 , wherein the primary amine mixture comprises greater than 0% of the primary amine.
13. The process of claim 11 , wherein the primary amine mixture comprises greater than 0% of the primary amine.
14. The process of claim 1 , wherein the Pigment Red 149 is obtained as a crude product in greater than 94% yield after a resulting reaction mixture is filtered and washed, and before any additional purification.