Meta toluene diamine (MTD) is an organic compound with a close formula C₆H₃(NH₂)₂CH₃ . It is one of the six TDA isomers that is made from hydrogenating 2,4 DNT in the presence of metal salt that acts as a catalyst.

Methylene diphenyl diisocyanate is an aromatic diisocyanate. Three isomers are common, varying by the positions of the isocyanate groups around the rings: 2,2′-MDI, 2,4′-MDI, and 4,4′-MDI. The 4,4′ isomer is most widely used, and is also known as 4,4′-diphenylmethane diisocyanato.

This compound, along with other toluenediamines, is used in the production of dyes, hair dyes, and other cosmetic colors.

Toluene diisocyanate (TDI) is an organic compound with the formula CH 3 C 6 H 3 (NCO) 2. Two of the six possible isomers are commercially important