The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 15, 1977
Filed:
Aug. 18, 1975
Adnan A Sayigh, North Haven, CT (US);
Kwok K Sun, Hamden, CT (US);
Henri Ulrich, Northford, CT (US);
The Upjohn Company, Kalamazoo, MI (US);
Abstract
2,2'- AND 2,4'-DIAMINODIPHENYLMETHANE ARE SELECTIVELY REMOVED FROM ADMIXTURES THEREOF WITH THE 4,4'-ISOMER BY HEATING THE ISOMER MIXTURE AT 30.degree. TO 100.degree. C in the presence of styrene, .alpha.-alkylstyrenes, or the mono- or diamino nuclear substituted derivatives thereof and a catalyst (mineral acid, clays, diatomaceous earth, zeolites). The styrene or .alpha.-alkylstyrene can be employed as such or generated in situ from a precursor therefor. The process is particularly useful in facilitating the isolation of substantially pure 4,4'-diaminodiphenylmethane from the polyamine mixture obtained by condensation of aniline and formaldehyde.