| 摘要 |
<p>Di(aminophenyl)methane having a high proportion of the o,p'-isomer (10 to 60 percent) and a substantial proportion of the o,o'-isomer (5 to 25 percent) is obtained by reacting at least 3.5 moles of aniline with 1 mole of formaldehyde, separating the water of condensation from the resulting mixture of aniline and anilino-acetal, heating the anhydrous mixture to 125 DEG C. to 205 DEG C. and adding a proton source (aniline hydrochloride preferred). The mixture of di(aminophenyl)-methane isomers can be separated from the mixture of polyamines so obtained and phosgenated to give a mixture of the corresponding isomeric di(isocyanatophenyl)methanes which mixture is a storage stable liquid. Alternatively the mixture of polyamines can be phosgenated, without separation of the di(aminophenyl)-methane, to give the corresponding mixture of polymethylene polyphenyl polyisocyanates. The latter mixture gives polyurethane foams of much lighter color than those obtained using comparable mixtures produced by prior art procedures.</p> |
