A process for converting a bis cyclic urea having the formula ##STR12## into a diisocyanate having the formula OCN--Cn H2n --NH--R--NH--Cn H2n --NCO wherein Cn H2n is the same in each formula and is alkylene from 4 to 12 inclusive and provided there are at least 4 carbon atoms in succession in the chain and R is the same in each formula and is a divalent radical selected from the group consisting