The final product is a cyclic tetramer of para t-butylphenol. There is a bridge in the ortho position of the phenol, and it consists of a single CH2 group. There is sodium hydroxide, where hydroxide is catalyst and sodium is a cation of the right size (which is really required to be sodium) to get a tetramer.
Potassium or rubidium will work too but hexamers or octamers will result.
This is an intermediate step, though, and there should first be an activated precursor. It is not there, I suppose. What exactly this precursor should be is not clear to me and I think to no one, but it should be green.
I have a setup for distillation but I close it down if I wish. The reason I let it distill is to be sure of the right reflux flow. If I close it down and reflux is not enough, I am afraid of pressure as has been said.
I am absolutely sure they do it in aquous environment though alternative synthesis exist which use paraformaldehyde in anhydrous environment. The synthesis I use does not specifically say reflux, but a erlenmeyer is heated on an oil bath of said temperature. I think a normal erlenmeyer will not stand any pressure so they must have left it open.