Tetramethyl xylene diisocyanate

An offering by Cytec Specialty Chemicals, the meta isomer of tetramethyl xylene diisocyanate (TMXDI) is interesting because it contains an aromatic ring, but the NCO groups themselves are aliphatic isocyanates and have reaction characteristics typical of aliphatic diisocyanates. It reacts even more sluggishly than the more standard aliphatic isocyanates because of steric interactions, making the reactions easier to control. Compounds such as dimethyl tin dilaurate, lead octoate, or tetrabutyl diacetyl distannox-ane have been shown to be effective catalysts for the isocyanate-hydroxyl reaction. The manufacturer claims that it is less toxic than many other isocyanates. 

Other high growth aliphatic isocyanates currently in production include isophorone diisocyanate IPDI (4,1) ex. Hiils, hydrogenated MDI HMDI (4.2) ex. Mobay, tetramethyl xylene diisocyanate TMXDI (4,3) and (4.4) ex. American Cyanamid and 3-isopropenyl dimethylbenzyl isocyanate TMI (4.5) ex. American Cyanamid [63a]. The latter two... 

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