Toluene diisocyanate exists in two isomeric forms (2,4-toluene diisocyanate and?2,6-toluene diisocyanate) which have similar properties and effects. Toluene diisocyanate is produced commercially as an 80:20 (2,4-toluene diisocyanate:2,6-toluene diisocyanate) mixture of the two isomers.