[pwl]

In order to produce / manufacture Methylene diphenyl diisocyanate (MDI) - all three isomers, 2,2'-MDI, 2,4'-MDI, and 4,4'-MDI - for use in Polyurethane production what is / are the base compounds required to actually make MDI?

Is it simply produced from straight forward Crude Oil fractionation OR .?

Thank you for your consideration and time - these sites are very handy !!!

[OC pro]

It is produced from the corresponding amine in combination with phosgene (gas) and heating. Phosgene is highly toxic and has been used as chemical warfare in WW 1. Although there exist alternatives for the preparation of MDI, multi-ton production with phosgene is by far the cheapest one.