An aromatic diisocyanate is methylene diphenyl diisocyanate (MDI). There are three common isomers: 2,2′-MDI, 2,4′-MDI, and 4,4′-MDI. These are distinguished by the locations of the isocyanate groups around the rings. The most common isomer, commonly known as 4,4′-diphenylmethane diisocyanate, is the Read More