Using O=C=O, CCCCCCCCC1(CCCCCCCC)c2ccccc2-c2ccccc21 to produce CCCCCCCCC1(CCCCCCCC)c2ccccc2-c2ccc(C(=O)O)cc21, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.