Patent GB-666198-A (GB)
Title: Process for the manufacture of optical brightening agents and their use
Filed: 1949-07-22
Abstract: Optical brightening agents of the formula <FORM:0666198/IV (b)/1> are made by reacting diazo compounds of amines <FORM:0666198/IV (b)/2> (where X is nitro, acylamino or triazinylamino free from chromophoric groups) with cinnamic acid or a nuclear substitution derivative thereof free from groups promoting azo coupling; any nitro groups in the product may then be reduced to amino and any primary amino groups may be reacted with triazinyl halides or with agents introducing carboxylic acid radicals or radicals derived from carbonic acid; thus Y in the product is acyl (including carbonic derivatives) or triazinyl and A and Y are free from substituents which displace light absorption into the visible spectrum.  Suitable nuclear substituents for the cinnamic acid are halogen, methyl, methoxy, nitro, acetamino or sulphonic acid, but not hydroxy or amino; if bathochromic groups such as azo or nitro are present, they are transformed in the final product, e.g. by reduction to amino groups.  Similar remarks apply to any substituents in the group Y.  The latter may be derived from a fatty acid (substituted or not), an aromatic carboxylic acid, a carbamic acid or a carbonic acid monoester; alternatively it may be derived from a cyanuric halide by partial or complete replacement of the halogen atoms by ammonia, amino or hydroxy groups. Aminotriazinyl groups may be reacted with formaldehyde to give methylol derivatives.  The reaction between the diazo compound and the cinnamic acid may be carried out in water or an organic solvent and the presence of a copper salt and a buffer is advantageous.  In the examples: (1) the amine (II, X = nitro) is diazotized and reacted with cinnamic acid; the nitro group in the product is reduced to amino and acylated with phenoxyacetyl chloride, benzoyl chloride or acetic anhydride; (2) as in (1), using ethyl or octyl chloroformate as acylating agent; (3) as in (1), using phenylacetyl chloride or ethoxyacetyl chloride as acylating agent; (4) as in (1) using p-methylcinnamic acid, and acylating with acetic anhydride or phenoxyacetyl chloride; (5) as in (1) using p-sulphocinnamic acid, and acylating with benzoyl chloride; (6) cyanuric chloride is reacted successively with 4-amino-41-styrylstilbene-2 : 21-disulphonic acid, sulphanilic acid and ammonia; (7) m-carbethoxy-phenyl isocyanate is reacted with 4-amino-41-styrylstilbene-2 : 21-disulphonic acid; di-(m-carbethoxyphenyl)-urea is a by-product; (8) 4-amino-41 - acetamino - stilbene - 2 : 21 - sulphonic acid is diazotized and reacted with cinnamic acid.  A list is given of further products obtained, showing in addition to the groups mentioned above: (1) m - sulpho-, p - methoxy-, m - acetamino-, o-chloro- and 2 : 6-dichloro-cinnamic acids; (2) acyl groups derived from propionic, p-toluic, phenylcarbamic, p-tolylcarbamic, p-tolyloxyacetic, p-chlorophenoxyacetic and p-methoxyphenoxy-acetic acids; (3) triazine substituents : dimethylamino, methylolamino, anilino and m-carboxyanilino.  The Specification as open to inspection under Sect. 91 is not limited to 2 : 21-substituents but refers to stilbene disulphonic and dicarboxylic acids in general (one group in each ring).  It is also stated that acylamino and acyloxy (e.g. carbethoxy-oxy) groups in the products may be hydrolysed to amino and hydroxy groups respectively.  This subject-matter does not appear in the Specification as accepted.ALSO:Brightening agents for dyed or undyed textile materials comprise stilbene derivatives of the formula <FORM:0666198/IV (c)/1> where Y is an acyl or triazinyl group and both Y and A are free from substituents which displace light absorption into the visible spectrum.  Suitable substituents for the ring A are halogen, methoxy, amino, acetamino or sulphonic acid.  If Y is acyl, it may be derived from a fatty acid (substituted or not), an aromatic carboxylic acid, a carbamic acid or a carbonic acid monoester, but not a sulphonic acid; if triazinyl, the other two ring-valencies may be attached to amino, substituted amino or hydroxy groups.  The compounds fluoresce green and have affinity for natural or regenerated cellulose, keratin, wool, silk and synthetic fibres, e.g. casein and nylon, and are fast to washing and alkalis.  The acylamino compounds are more suited to wool while the triazinylamino compounds which are more yellowish may be used on regenerated cellulose or mixtures thereof with wool.  In the examples: (1) bleached wool is treated with the compound (Y=COOEt, A unsubstituted) in acetic acid; (2) silk or nylon is treated with the compound (Y=C6H5-O-CH2-CO-, A unsubstituted) in formic acid; (3) regenerated cellulose is treated with the compound of (2) and sodium sulphate; (4) wool, cotton or regenerated cellulose is treated with the compound (Y=2-amino-4 - (p - sulphophenyl) - amino - 6 - triazinyl-, A unsubstituted), if desired in conjunction with another compound which has a red or violet fluorescence, e.g. 4 : 41-diphenylureido-stilbene-2 : 21-disulphonic acid; by blending the two in the correct proportion, the shade of a white dyeing may be varied as desired from violet-tinted through pure white to green-tinted; (5) a similar shading may be effected using the compound (Y=m-carbethoxy-phenyl carbamyl, A unsubstituted) on wool, silk, nylon, cotton or regenerated cellulose; (6) other suitable compounds for cellulosic and other fibres are (Y=C5H6-CH2-CO-, A unsubstituted), (Y= acetyl, A=p-methyl), (Y=C6H5-O-CH2-CO-, A=p-methyl) and (Y=benzoyl, A=p-sulphonic acid).  A list of further suitable compounds is given.  According to the Specification as open to inspection under Sect. 91, there may also be used disulphonic acids in other than the 2 : 21-positions and dicarboxylic acids.  It is also stated that A may be substituted with hydroxy groups.  This subject-matter does not appear in the Specification as accepted.