| 摘要 |
Through condensation ortho- and para-isomers of methylene dianiline (MDA) as well as PMPPA are produced as condensation products from arylamines, especially from aniline, and formaldehyde in the presence of acid catalysts, in which at least one component is a perfluoro-carbonic acid. From this mixture of the condensation products, 4,4'-MDA (p-isomer) of high purity is obtained by crystallization while the homogeneous aqueous solution obtained is being cooled down. It has been discovered that the 4,4'-MDA salts of the perfluoro-carbonic acids are less soluble in water than the corresponding salts of the o-isomers and the PMPPA.
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