Using COc1ccccc1OC(=O)c1ccccc1O, O=C(O)c1ccccc1O to produce COc1ccccc1OC(=O)c1ccccc1OC(=O)c1ccccc1O, please predict the solvent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.