Fluorescent whitening agents

Bleaching and dyeing; fluid treatment and chemical modification – Dye or potential dye composition – additive – treatment,... – Fluorescent dye – e.g. – stilbene – benzimidazole – benzoxazole,...

Reexamination Certificate

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C008S919000, C544S193200, C427S412000

Reexamination Certificate

active

06464735

ABSTRACT:

The present invention relates to new compounds, in particular to new 4,4′-diaminostilbene-2,2′-disulfonic acid compounds which are useful as fluorescent whitening agents or for inhibiting (quenching) the effect of anionic fluorescent whitening agents on substrates.
In WO 96/00221, there are described optical brightening agents for textiles, paper etc. The disclosed compounds have the formula:
in which R
a
and R
b
are the same or different and each has the formula —NR
c
R
d
in which R
c
is hydrogen; C
1
-C
6
alkyl which is optionally substituted by at least one of mercapto, C
1
-C
6
thioalkyl, OH and SO
3
M′ in which M′ is hydrogen, a colourless cation or an amine-derived cation; or —R
e
(CO
2
M′)
x
in which R
e
is an aliphatic moiety having 1-6 carbon atoms, those valencies not bonded with groups CO
2
M′ being bonded with at least one of hydrogen, mercapto, C
1
-C
6
thioalkyl, OH and SO
3
M′ in which M′ has its previous significance and x is an integer from 1 to 4, provided that, when R
c
is C
1
-C
6
alkyl which is optionally substituted by at least one of mercapto, C
1
-C
6
thioalkyl, OH and SO
3
M′, R
c
is substituted with at least both of OH and SO
3
M′; R
d
is R
c
, hydrogen or C
3
-C
6
alkyl, provided that R
c
and R
d
cannot both be hydrogen and that, when one of R
c
and R
d
is hydrogen, the other cannot be —(NHCH
2
CO
2
H); or R
c
and R
d
, together with the nitrogen atom, form a ring having from 5-6 members only, one of which is heterocyclic, which ring is singly substituted with —COOM′ or —SO
3
M′; and each R
f
, independently, is hydrogen, methyl, C
1
-C
6
alkoxy or halogen.
A new class of 4,4′-diaminostilbene-2,2′-disulfonic acid compounds has now been found most of which are useful as fluorescent whitening agents and which have superior properties with respect to the compounds disclosed in WO 96/00221, and others of which are useful for inhibiting (quenching) the effect of anionic fluorescent whitening agents on substrates.
Accordingly, the present invention provides new compounds having the formula:
in which X is O or, preferably, NH; M is hydrogen, an alkali metal atom, ammonium or a cation formed from an amine; each R
1
, independently, is an aminoacid residue from which a hydrogen atom on the amino group has been removed; n is 1 or 2; and each R
2
, independently, is hydrogen, C
1
-C
3
alkyl, halogen, cyano, COOR in which R is hydrogen or C
1
-C
3
alkyl, CONH—R in which R has its previous significance, SO
2
NH—R in which R has its previous significance, NH—COR in which R has its previous significance, SO
3
M in which M has its previous significance or, when n is 1, R
2
can also be CO—R
3
in which R
3
is C
1
-C
3
alkyl or phenyl;
provided that those compounds are excluded in which
a) X is NH, n is 1 and R
2
is SO
3
M in which M has its previous significance; or
b) X is NH, n is 2 and one R
2
is SO
3
M in which M has its previous significance, and the other R
2
is hydrogen, methyl or halogen; or
c) X is NH, n is 1, R
1
is glycine and R
2
is H or CO
2
H; or
d) X is NH, n is 2, each R
2
is SO
3
M in which M has its previous significance and the SO
3
M groups are in 2,5-positions in the phenyl ring and R
1
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.
Preferably M is hydrogen, Na, K, Ca, Mg, ammonium, mono-, di-, tri- or tetra-C
1
-C
4
alkylammonium, mono-, di- or tri-C
1
-C
4
hydroxyalkylammonium or ammonium that is di- or tri-substituted with a mixture C
1
-C
4
alkyl hydroxyalkyl groups. Preferably each M is Na.
A halogen substituent R
2
may be fluorine, bromine or iodine but is preferably chlorine.
In the compounds of formula (1), n is preferably 1 and R
2
is preferably hydrogen, methyl, chlorine, cyano, COOH, COO-methyl, CONH
2
, CONH-methyl, SO
2
NH
2
, SO
2
NH-methyl or NH-COmethyl.
Preferably, each of the aminoacid residues R
1
is the same. Examples of preferred aminoacid residues R
1
include those having the formula —NH—CH(CO
2
H)—R
3
in which R
3
is hydrogen or a group having the formula —CHR
4
R
5
in which R
4
and R
5
, independently, are hydrogen or C
1
-C
4
alkyl optionally substituted by one or two substituents selected from hydroxy, thio, methylthio, amino, carboxy, sulfo, phenyl, 4-hydroxyphenyl, 3,5-diiodo-4-hydroxyphenyl, &bgr;-indolyl, &bgr;-imidazolyl and NH═C(NH
2
)NH—.
Specific examples of aminoacids from which such preferred aminoacid residues R
1
are derived include glycine, alanine, sarcosine, serine, cysteine, phenylalanine, tyrosine (4-hydroxyphenylalanine), diiodotyrosine, tryptophan (&bgr;-indolylalanine), histidine ((&bgr;-imidazolylalanine), &agr;-aminobutyric acid, methionine, valine (&agr;-aminoisovaleric acid), norvaline, leucine (&agr;-aminoisocaproic acid), isoleucine (&agr;-amino-&bgr;-methylvaleric acid), norleucine (&agr;-amino-n-caproic acid), arginine, ornithine (&agr;,&dgr;-diaminovaleric acid), lysine (&agr;,&egr;-diaminocaproic acid), aspartic acid (aminosuccinic acid), glutamic acid (&agr;-aminoglutaric acid), threonine, hydroxyglutamic acid and taurine, as well as mixtures and optical isomers thereof. Of these aminoacids from which such preferred aminoacid residues R
1
are derived, sarcosine, taurine, glutamic acid and aspartic acid are particularly preferred.
A further preferred example of an aminoacid from which an aminoacid residue R
1
may be derived is iminodiacetic acid.
Other, less preferred examples of aminoacids from which aminoacid residues R
1
may be derived include cystine, lanthionine, proline and hydroxyproline.
In addition to the above-mentioned preferred classical aminoacids, R
1
may also be the residue of an aromatic aminoacid such as p-aminobenzoic acid or o-aminobenzoic acid.
In the compounds of formula (1), when n is 1 and each R
2
is CO—R
3
in which R
3
is C
1
-C
3
alkyl or phenyl, preferably methyl, such compounds are not useful as fluorescent whitening agents, rather they are are useful for inhibiting (quenching) the effect of anionic fluorescent whitening agents on substrates.
The compounds of formula (1) may be produced by reacting, under known reaction conditions, cyanuric chloride, successively, in any desired sequence, with each of 4,4′-diamino-2,2′-stilbene disulfonic acid, an amino compound capable of introducing a group
in which R
2
and n have their previous significance, and a compound capable of introducing a group R
1
, in which R
1
has its previous significance.
The starting materials are known compounds which are readily available.
Most of the compounds of formula (1) are excellent fluorescent whitening agents for substrates such as textiles and, in particular, for paper.
Accordingly, the present invention provides a method for the fluorescent whitening of a substrate comprising contacting the substrate with a compound having the formula (1A):
in which X is O or NH; M is hydrogen, an alkali metal atom, ammonium or a cation formed from an amine; each R
1
, independently, is an aminoacid residue from which a hydrogen atom on the amino group has been removed; n is 1 or 2; and each R′
2
, independently, is hydrogen, C
1
-C
3
alkyl, halogen, cyano, COOR in which R is hydrogen or C
1
-C3alkyl, CONH—R in which R has its previous significance, SO
2
NH—R in which R has its previous significance, NH—COR in which R has its previous significance or SO
3
M in which M has its previous significance;
provided that those compounds are excluded in which X is NH, n is 2 and one R
2
is SO
3
M in which M has its previous significance, and the other R
2
is hydrogen, methyl or halogen.
When used for the fluorescent whitening of paper, the compound of formula (1A) according to the present invention may be applied to the paper substrate in the form of a paper coating composition, or directly in the size press.
In one preferred aspect, the present invention provides a method for the fluorescent whitening of a paper surface, comprising contacting the paper

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