| abstract |
Compounds of formula (I): [where: R1 is a direct bond, oxygen, a group >CH2, sulphur, a group >C=O, a group-(CH2)2- or a group-N-Ra, where Ra is hydrogen or alkyl; R3, R4, R5 and R6 are hydrogen or substituentsα; R8, R9, R10 and R11 are hydrogen, hydroxy or alkyl; or R9 and R11 are joined to form a fused ring system with the benzene rings to which they are attached; R7 is a direct bond, oxygen ora -CH2-group; p is 0 or 1; substituentsα are: alkyl, alkoxy, alkenyl, halogen, nitrile, hydroxyl, aryl, aralkyl, aryloxy, aralkyloxy, arylalkenyl, cycloalkyl, carboxy, carboxyalkoxy, alkoxycarbonyl, aryloxycarbonyl, alkylcarbonyloxy, alkanesulphonyl, arenesulphonyl, alkanoyl or arylcarbonyl; n is 1 to 12; R12 is hydrogen, methyl or ethyl; A is a group -[O(CHR13CHR14)a]y-, -[O(CH2)bC0]y-, or -[O(CH2)bC0](y-1)-[O(CHR13CHR14)a]-, where: one of R13 and R14 is hydrogen and the other is hydrogen, methyl or ethyl; a is 1 to 2; b is 4 to 5; Q is a residue of a polyhydroxy compound having from 2 to 6 hydroxy groups; x is a number greater than 1 but no greater than the number of available hydroxyl groups in Q; y is a number from 1 to 10; and X- is an anion]; and esters thereof are useful as cationic photoinitiators, especially for use in surface coating applications, such as printing inks and varnishes, and which are intended to be cured by polymerisation initiated by radiation. |