Stabilization of c.i. pigment yellow 139

A process for enhancing alkali stability of a pigment of formula (I):

• the process comprising adding an adduct to the pigment of formula (I), said adduct being selected from the group consisting of
• (b1) an adduct comprising:
• a compound of formula (II):
• or a tautomeric form thereof,
• wherein
• X is O, S or NW;
• Y is O, S or NW;
• -A-B— is selected from the group consisting of —CR2═CR3—, —CR4R5—CR6R7—, —CY—CR8R9—, —CX—NR10—, —CR11═N—, —CR12R13—NR14— and
• R is hydrogen, C1-C8alkyl, C3-C7cycloalkyl, C6-C10aryl or C7-C10aralkyl;
• R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13 and R14 are independently of each other hydrogen, halogen, C1-C8alkyl, C2-C8alkenyl or C6-C10aryl, or
• R2 and R3 form a benzoannellated ring;
• said alkyl, cycloalkyl or alkenyl is unsubstituted or substituted with halogen or OH;
• said aryl or benzoannellated ring is unsubstituted or substituted with halogen, OH or C1-C4alkyl;
• and
• a compound of formula (III)
• or a tautomeric form thereof,
• wherein
• Z is N or CR18,
• R18 is hydrogen, C1-C8alkyl, C2-C8alkenyl, C6-C10aryl or C7-C10 aralkyl;
• R15, R16 and R17 are independently of each other hydrogen, C1-C8alkyl, C6-C10aryl, C7-C10aralkyl or a group of formula (IV):
• said alkyl or alkenyl is unsubstituted or substituted with halogen or OH;
• and
• said aryl is unsubstituted or substituted with halogen, OH or C1-C4alkyl;
• or
• (b2) an adduct comprising:
• a compound of formula (II):
• or a tautomeric form thereof,
• wherein
• X is O, S or NR1;
• Y is O, S or NR1;
• -A-B— is selected from the group consisting of —CR2═CR3—, —CR4R5—CR6R7—, —CY—CR8R9—, —CR11—N—, —CR12R13—NR14— and
• R1 is hydrogen, C1-C8alkyl, C3-C7cycloalkyl, C6-C10aryl or C7-C10aralkyl;
• R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13 and R14 are independently of each other hydrogen, halogen, C1-C8alkyl, C2-C8alkenyl, or C6-C10aryl, or
• R2 and R3 form a benzoannellated ring;
• said alkyl, cycloalkyl or alkenyl is unsubstituted or substituted with halogen or OH,
• said aryl or benzoannellated ring is unsubstituted or substituted with halogen, OH or C1-C4alkyl;
• and
• (b3) an adduct comprising:
• a compound of formula (III):
• or a tautomeric form thereof,
• wherein
• Z is N or CR18;
• R18 is hydrogen, C1-C8alkyl, C2-C8alkenyl, C6-C10aryl or C7-C10aralkyl;
• R15, R16 and R17 are independently of each other hydrogen, C1-C8alkyl, C6-C10aryl, C7-C10aralkyl or a group of formula (IV):
• said alkyl or alkenyl is unsubstituted or substituted with halogen or OH;
• and
• said aryl is unsubstituted or substituted with halogen, OH or C1-C4alkyl.