prov:value
| - wherein R1 is hydrogen, a (C1 to C4)alkyl group, or a phenyl group, preferably hydrogen or a methyl group; R2 is a single bond or a divalent linking group that joins an ethylenically unsaturated group to functional group A and preferably contains up to 34, more preferably up to 18, most preferably up to 10 carbon atoms, and, optionally, oxygen and nitrogen atoms and, when R2 is not a single bond,
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