abstract |
There is provided a compound of formula (I): In this formula, R is C 1 -C 18 alkyl, C 5 -C 18 cycloalkyl, C 3 -C 18 alkenyl or C 3 -C 18 alkynyl; With the proviso that R is not methyl, ethyl, hexyl, octyl or allyl when the —OR group in formula (I) is present at the 2,2′-position of the benzene ring. |