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Methylene diphenyl diisocyanate (MDI) 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 diisocyanate. [3] This isomer is also known as Pure MDI.
The global market for diisocyanates in the year 2000 was 4.4 million tonnes, of which 61.3% was methylene diphenyl diisocyanate (MDI), 34.1% was toluene diisocyanate (TDI), 3.4% was the total for hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI), and 1.2% was the total for various others. [18]
More specifically, it is an aliphatic diisocyanate. It is a water white liquid at room temperature and is manufactured in relatively small quantities. It is also known as 4,4'-methylenedi(cyclohexyl isocyanate) or methylene bis(4-cyclohexylisocyanate) [2] and has the formula CH 2 [(C 6 H 10)NCO] 2.
4,4′-Methylenedianiline (MDA) is an organic compound with the formula CH 2 (C 6 H 4 NH 2) 2. It is a colorless solid, although commercial samples can appear yellow or brown. It is a colorless solid, although commercial samples can appear yellow or brown.
A diisocyanate, often 4,4’-methylenediphenyldiisocyanate (MDI), is reacted with trimellitic anhydride (TMA). The product achieved at the end of this process is a high molecular weight, fully imidized polymer solution with no condensation byproducts, since the carbon dioxide gas byproduct is easily removed.
4,4'-Diaminodicyclohexylmethane is the name for organic compounds with the formula CH 2 (C 6 H 10 NH 2) 2. It is classified as a diamine. In the epoxy industry it is often referred to as PACM, short for para-diaminodicyclohexylmethane. It is used as a curing agent for epoxy resins [1] It finds particular use in epoxy flooring. [2]
Characteristic of other isocyanates, it reacts with amines to give ureas. [2] Similarly, reacts with alcohols to form carbamates. It is used in addition with triethylamine to activate nitro groups to undergo (C,O) 1,3-dipolar cycloaddition (as opposed to O,O). The nitro group (RCH 2 NO 2) is converted to oxime-like dimers in the reaction: [3]
As of 2019, it is the world's largest producer of the polyurethane raw material methylene diphenyl diisocyanate (MDI). [15] According to another source, the listed company is the second largest producer of the world for aliphatic di isocyanate (ADI) as well as the largest producer of China for toluene diisocyanate (TDI).