There is a medication called Levothyroxine which some of us have to take if we have had a thyroidectomy (i.e. removal of thyroid gland as a result of cancer) or have a non functioning thyroid.
This medication consists of an organic compound called tetratiodothyronine or T4 for short. T4 because it has 4 iodine atoms attached to it’s rings, 2 to the outer phenolic benzene ring and 2 to the inner tyrosyl ring.
T4 is an inactive form and a very important process takes place where the body must knock off one of the iodine atoms (it’s done in the liver) in order to get to the active molecule called tri- iodothyronine or (T3), T3 because this one only has 3 iodine molecules. T3 is the compound which gives the body energy.
My question is, what sort of bond holds the iodine atoms to those benzene rings? Is it a Van de Waal bond? If not, does anyone know the name of that bond? And secondly, is such a bond variable in strength even in the very slightest. i.e. could one manufacture of T4 make a molecule where the iodine bond is too strong and makes it difficult for the body to knock off the iodine atom but another manufacturer makes a compound with a very slightly weaker bond, and thus easier to knock off?