Using ClCCCCCBr, CCOC(=O)C(CCCC(F)(F)C(F)(F)F)C(=O)OCC to produce CCOC(=O)C(CCCCCCl)(CCCC(F)(F)C(F)(F)F)C(=O)OCC, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.