Toluene diisocyanate (TDI) is an organic compound with the formula CH3C6H3(NCO)2. TDI is produced in the pure state, but TDI is often marketed as 80/20 and 65/35 mixtures of the 2,4 and 2,6 isomers respectively. All isomers of TDI are colorless, although commercial samples can appear yellow.