What is the name of the acid the dematologist used to remove the wart from my sons leg

it starts with a "D" like dichlocloric? or something do you know?

It was probably bichloracetic acid. This can be used to remove small skin lesions. This is a great chemical & extremely powerful! If you are going to remove a lesion with it, it is a good idea to isolate the area with petroleum jelly or some type of ointment. This will also help contain the bichloracetic acid in the desired area.