Preparation of diaminodiphenyl ethers
AssigneeMallinckrodt Inc.
InventorsPhilip H. Merrell, Michael F. Ellis
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Abstract
Diaminodiphenyl ethers (DADPE's) are prepared by refluxing sodium or potassium aminophenate with chloronitrobenzene in dimethylformamide. The reaction mixture is hydrogenated directly without isolating the resulting intermediate product, aminophenyl-nitrophenyl ether, to form the corresponding DADPE, e.g., oxydianiline (ODA). The DADPE is crystallized from the hydrogenated reaction mixture in the presence of an aliphatic alcohol, which may be added to the reaction mixture prior to, during, or after hydrogenation. The resulting crystallized DADPE is typically of high purity and excellent color.
Claims6
A process for preparing a high-purity, 4,4'-diaminodiphenyl ether product containing above 98% of the 4,4'-diaminodiphenyl ether per se and having substantial freedom from pin tint which comprises (a) refluxing a reaction mixture comprising approximately equimolar amounts of (i) p-aminophenol, (ii) p-chloronitrobenzene, and (iii) potassium carbonate in a liquid medium comprising dimethylformamide, (b) hydrogenating the resulting mixture in the presence of a catalyst, (c) recovering the dimethylformamide by distillation, and (d) crystallizing the 4,4'-diaminodiphenyl ether product from the residue by cooling said reaction mixture in the presence of a precipitation-effective amount of an aliphatic alcohol selected from the group consisting of methanol, ethanol, and isopropanol.
Dependencies are inferred from the claim text.