Purification process for MDA

Details Purification process for MDA Purification process for MDA

1975-08-18

1977-06-14

Hines, Robert V.

Chemistry of carbon compounds

Miscellaneous organic carbon compounds

C-metal

C07C 8516

Patent

active

040297055

ABSTRACT:
A process is described for the selective removal of 2,2'- and 2,4'-diaminodiphenylmethanes from mixtures containing 2,2'-, 2,4'- and 4,4'-diaminodiphenylmethanes and polyamines by heating these mixtures in the presence of aqueous hydrochloric acid (55 to 95 percent by equivalents based on the total amine in the starting material) and formaldehyde. The process is particularly useful to facilitate the isolation of substantially pure 4,4'-isomer from aniline-formaldehyde condensation products. The pure 4,4'-isomer is a valuable intermediate for polyamides as well as for the corresponding diisocyanate. The by-products of the reaction are oligomeric polymethylene polyphenyl polyamines which are also useful as curing agents and intermediates for polymethylene polyphenyl polyisocyanates and the like.

REFERENCES:
patent: 3676497 (1972-07-01), Recchia
patent: 3857890 (1974-12-01), Recchia
patent: 3860637 (1975-01-01), Bentley
Allied Chemical, "Aniline", p. 35 (1964).

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