COc1cc(C2C3=C(COC3=O)Oc3cc4c(cc32)OCO4)ccc1OC(C)=O
A rotatable bond is defined as any single non-ring bond, attached to a non-terminal, non-hydrogen atom. Amide C-N bonds are not counted because of their high barrier to rotation.  How many rotatable bonds does the molecule have?