C=CC(C)(C)n1cc(C2=C(O)C(=O)C(c3c(CC=C(C)C)[nH]c4ccccc34)=C(O)C2=O)c2ccccc21
Hydrogen bond acceptor is the chemical compound which contains the lone electron pairs that participate in the hydrogen bond formation. This compound should contain a more electronegative atom (more electronegative than hydrogen) with lone electron pairs. Then it can attract protons from a donor. Moreover, the electronegative atoms usually involved in hydrogen bonding are oxygen, nitrogen and fluorine. How many hydrogen bond acceptors does the molecule contain?