Organic compounds -- part of the class 532-570 series – Organic compounds – Isocyanate esters
Reexamination Certificate
2007-03-06
2007-03-06
Zucker, Paul A. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Isocyanate esters
C560S347000, C564S326000
Reexamination Certificate
active
11257713
ABSTRACT:
The present invention relates to a process for the preparation of di- and polyamines of the diphenylmethane series, and to the preparation of di- and poly-isocyanates of the diphenylmethane series from these di- and poly-amines. The di- and poly-amines of the diphenylmethane series are prepared by the reaction of aniline and formaldehyde in the presence of hydrochloric acid. In with the present invention, the hydrochloric acid employed contains less than 0.001 wt. % of metal ions which are divalent and/or more than divalent.
REFERENCES:
patent: 6720455 (2004-04-01), Hagen et al.
patent: 2003/0045745 (2003-03-01), Hagen et al.
patent: 2003/0176626 (2003-09-01), Hagen et al.
Chem. Soc. Rev., 3(2), (month unavailable) 1974, H.J. Twitchett, pp. 209-231, “Chemistry of the Production of Organic Isocyanates”.
Kirk-Othmer Encycl. Chem. Technol., 3rd, ed., 2, (month unavailable) 1978, William M. Moore, pp. 338-348, “Methylenedianiline”.
Grabowski Stefan
Müller Heinz-Herbert
Wershofen Stefan
Bayer MaterialScience AG
Brown N. Denise
Gil Joseph C.
Whalen Lyndanne M.
Zucker Paul A.
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