C - Chemistry – Metallurgy – 07 – C
Patent
C - Chemistry, Metallurgy
07
C
260/455.7
C07C 205/06 (2006.01) C07C 209/36 (2006.01) C08G 18/76 (2006.01)
Patent
CA 1171097
Mo-2273 LeA 20,533 POLYISOCYANATES OF THE DIPHENYL METHANE SERIES AND PROCESS FOR THE PRODUCTION THEREOF ABSTRACT OF THE DISCLOSURE A polyisocyanate or mixture of polyisocyanates in which the main component(s) correspond to the formula: Image in which R1, R2, and R3 each represent hydrogen or a saturated alkyl group containing from 1 to 12 carbon atoms, provided that at least two of these radicals represent hydrogen; and m, n, o and p each represent 0 or 1, provided that when m, n, o and/or p represent 0, the free valency is taken up by a hydrogen atom and that the sum of m + n + 0 + p is greater than 1 on a statistical average. Such polyisocyanate or mixture of polyisocyanates may be produced hy first reacting a 4-nitrobenzyl halide, a 3-nitrobenzyl halide, a benzyl halide, a benzyl alcohol or a nitrobenzyl chloride isomer mixture with nitrobenzene, an alkyl-substituted nitro- benzene, an alkyl benzene or benzene in the presence of a Friedel-Crafts or an acid catalyst. This reaction product is then nitrated, the nitro groups are converted to amino groups by reduction or hydrogenation and the amino compound(s) subsequently phosgenated to form the polyisocyanate(s). The purity of the product polyisocyanate may be improved by distilling off secondary products before and/or after the phosgenation. LeA 20,533
383031
Brockelt Michael
Knofel Hartmut
Aktiengesellschaft Bayer
Norton Rose Or S.e.n.c.r.l. S.r.l./llp
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