METHOD OF PREPARING A MONOMERIC PHOTOINITIATOR

The present disclosure provides a method of preparing a compound of Formula (V) wherein n of radicals R 6' to R 9' are -R b OC(O)C(R 13 )=CH 2 , and further wherein R 13 is H or C 1 alkyl, n is an integer of from 1 to 3 and for each of said n radicals, R b is independently selected from a covalent bond, C 2 -C 12 alkylene, C 3 -C 18 cycloalkylene or C 6 -C 18 arylene. In a first method step i), a disulfide compound of Formula (I) is reacted in an acidic medium having a pH of ≤ 4 with a hydroxyl functional compound of Formula (II) to yield a compound of Formula (III), wherein: R 2 to R 5 are independently selected from H or C 1 -C 6 alkyl, R 6 to R 9 correspond to said substituents R 6' to R 9' and are independently selected from H, C 1 -C 6 alkyl, C 1 -C 6 alkoxy, C 1 -C 12 alkoxyalkyl, SR 12 , COOR 12 and N(R 12 ) 2 ; R 10 and R 11 are H; and, each R 12 is independently selected from C 1 -C 6 alkyl or C 6 -C 18 aryl, subject to the proviso that n of radicals R 6 to R 9 are R b (OH) and for each of said n radicals, R b is independently selected as defined above. In a second step ii) said compound of Formula (III) is reacted in an inert aprotic solvent with a (meth)acrylating agent of Formula (IV) to yield said compound of Formula (V), wherein: in Formula (IV), X is halide or -OC(O)C(R 13 )=CH 2 ; and, the number of moles of (meth)acrylate groups provided by said compound of Formula (IV) is at least equimolar with the number of moles of hydroxyl groups provided by the compound of Formula (III).