Synthesis Process Optimization of Di Meryl Diisocyanate (DDI) Curing Agent

Aromatic and aliphatic isocyanates are used in the production of polyurethane. Dimeryl Diisocyanate (DDI), as an emerging biological aliphatic diisocyanate, has many advantages such as low toxicity, low vapor pressure and insensitivity to moisture and is one of the important isocyanates that can be used as a curing agent as well as a viscosity improver and plasticizer in the formulation of propellants, PBX and polyurethanes. In this research, dimeryl diisocyanate (DDI) has been investigated through a two-step method of optimization and influence on various factors. Thus, in the first step, the reaction of the acid dimer with the chlorination agent at room temperature led to the preparation of the acyl chloride compound with an efficiency of 98%, and in the second step, azidation of this intermediate using sodium azide and Curtius rearrangement produced the desired product with an efficiency of it created 89%. The product obtained by this method does not have the disadvantages of the phosgene method, such as high toxicity, unwanted side reactions, and difficult process conditions, and the overall reaction efficiency was 87%.