The dehydrosulfurization of bisthioureas containing at least one aromatic residue results in the corresponding biscarbodiimides. Biscarbodiimides with bulky groups, such as t-butyl and 2,6-xylyl, can be isolated without any polymerization and disproportionation; the steric hindrance of the bulky groups makes such isolation possible. Polymerization and disproportionation interrupt the isolation of biscarbodiimides with less bulky groups. Despite their nonpolymerizability, they give rise to the other known addition reaction of aromatic carbodiimides.
对含有至少一个芳香残基的双
硫代
脲类进行脱
水硫化,可得到相应的双卡二
亚胺。带有大体积基团(如 t-丁基和 2,6-xylyl 基)的双碳二
亚胺可以在不进行任何聚合和歧化的情况下分离出来;大体积基团的立体阻碍作用使得这种分离成为可能。而聚合和歧化反应则会中断具有较少笨重基团的双碳二亚酰胺的分离。尽管双碳化二
亚胺不具有聚合性,但它们却能引起其他已知的芳香族碳二
亚胺加成反应。