FLUORESCENT WHITENING AGENTS

摘要

The present invention provides new compounds having formula (1), in which X is O or, preferably, NH; M is hydrogen, an alkali metal atom, ammonium or a cation formed from an amine; each R1, independently, is an aminoacid residue from which a hydrogen atom on the amino group has been removed; n is 1 or 2; and each R2, independently, is hydrogen, C1-C3alkyl, halogen, cyano, COOR in which R is hydrogen or C1-C3alkyl, CONH-R in which R has its previous significance, SO2NH-R in which R has its previous significance, NH-COR in which R has its previous significance, SO3M in which M has its previous significance or, when n is 1, R2 can also be CO-R3 in which R3 is C1-C3alkyl or phenyl; provided that those compounds are excluded in which a) X is NH, n is 1 and R2 is SO3M in which M has its previous significance; or b) X is NH, n is 2 and one R2 is SO3M in which M has its previous significance, and the other R2 is hydrogen, methyl or halogen; or c) X is NH, n is 1, R1 is glycine and R2 is H or CO2H; or d) X is NH, n is 2, each R2 is SO3M in which M has its previous significance and the SO3M groups are in 2,5-positions in the phenyl ring and R1 is D,L-alanine, L-valine, L-leucine; L-isoleucine, L-threonine, L-aspartic acid, L-glutamic acid, L-phenylalanine, L-proline, D,L-methionine or glycine. Most of the new class of 4,4'-diaminostilbene-2,2'-disulfonic acid compounds are useful as fluorescent whitening agents, especially for paper.