| 摘要 |
A novel process for making 4,4'-methylene diphenyl diisocyanate and corresponding oligomer in improved selectivity and yield comprises condensing formaldehyde and aniline under neutral or basic conditions to yield an anil condensate, followed by reacting the anil condensate with additional aniline and a protonic salt of aniline to yield 4,4'-methylene dianiline and corresponding oligomer, then followed by conventional phosgenation.
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