Dimethine compounds of the coumarin series, a process for their preparation and their use as luminous dyestuffs

Dimethine compounds of the coumarin series of the general formula ##STR1## with the substituent meanings given in the description are used for dyeing synthetic fibre materials, in particular those of polyester, polyamide, polyurethanes, polypropylene and polyacrylonitrile. Clear, luminous-red dyeings of high brilliancy are obtained. The dyestuffs can also be used as laser dyestuffs and as energy converters in light-collecting systems.

The invention relates to dimethine dyestuffs of the general formula 
##STR2## 
wherein A denotes O, S, N-alkyl, N-aryl or N-aralkyl, 
B denotes the remaining members of a quasiaromatic heterocyclic ring 
system, 
R.sup.1 denotes alkyl, alkenyl, cycloalkyl, aralkyl or aryl, 
R.sup.2 denotes hydrogen, alkyl or aralkyl and 
R.sup.3 and R.sup.4 each denote hydrogen or methyl, and wherein 
R.sup.1 and R.sup.2 together can form a radical of the formula 
--(CH.sub.2).sub.2 --Z--(CH.sub.2).sub.2 --, 
R.sup.1 and R.sup.4 together can form a radical of the formula 
--(CH.sub.2).sub.2 --, --(CH.sub.2).sub.3 -- or --C(CH.sub.3).sub.2 
--CH.sub.3 --CH(CH.sub.3)-- and 
R.sup.2 and R.sup.3 together can form a radical of the formula 
--(CH.sub.2).sub.3 --, 
wherein 
Z represents A, CH.sub.2 or a direct bond, and wherein the cyclic and 
acyclic radicals can carry substituents which are customary in dyestuff 
chemistry. 
Suitable alkyl radicals R.sup.1 and R.sup.2 are C.sub.1 -C.sub.5 -alkyl 
radicals, which can carry a substituent such as chlorine, bromine, cyano 
or C.sub.1 -C.sub.4 -alkoxycarbonyl. 
By alkenyl there are preferably to be understood C.sub.3 -C.sub.4 -alkenyl 
radicals. 
Cycloalkyl radicals which may be mentioned are, above all, cyclohexyl and 
cyclopentyl. 
Suitable aralkyl radicals R.sup.1 and R.sup.2 are, in particular, 
phenyl-C.sub.1 -C.sub.3 -alkyl radicals. 
Z preferably represents O, NH, NCH.sub.3, CH.sub.2 or a direct bond. 
Suitable aryl radicals are, in particular, phenyl radicals, which can be 
mono-, di- or tri-substituted by methyl, chlorine or C.sub.1 -C.sub.2 
-alkoxy. 
Suitable heterocyclic ring systems which A and B can form, together with 
##STR3## 
are the benzoxazole, benzimidazole, quinazolone, 1,3,4-oxadiazole and 
1,3,4-thiadiazole rings, which can in turn be mono- or di-substituted by 
C.sub.1 -C.sub.4 -alkyl, CF.sub.3, C.sub.1 -C.sub.4 -alkoxy, halogen, 
C.sub.1 -C.sub.4 -alkoxycarbonyl, COOH, C.sub.1 -C.sub.4 -alkylsulphonyl, 
C.sub.5 -C.sub.6 -cycloalkyl, phenyl, phenyl-C.sub.1 -C.sub.3 -alkyl or 
SO.sub.3 H, it also being possible for 2 adjacent substituents together to 
form a radical of the formula --(CH.sub.2).sub.2 --O--, --(CH.sub.2).sub.3 
--, --(CH.sub.2).sub.4 --, --OCH.sub.2 O--, --O--CH.sub.2 --CH.sub.2 --O-- 
or --C(CH.sub.3).sub.2 --CH.sub.2 --CH.sub.2 --C(CH.sub.3).sub.2 --. The 
heterocyclic systems can also be benzo-fused. 
In the context of the invention, preferred dimethine dyestuffs correspond 
to the formula 
##STR4## 
wherein Z.sup.1 and Z.sup.2 each by itself represents a C.sub.1 -C.sub.4 
-alkyl radical which is substituted by Cl or CN, or phenyl-C.sub.1 
-C.sub.3 -alkyl, 
Z.sup.3 and Z.sup.4 independently of one another represent hydrogen, 
D represents a radical of the formula 
##STR5## 
X represents O, S, NH, N-C.sub.1 -C.sub.4 -alkyl, N-benzyl, N-phenyl or 
NH--CO (CO on the aromatic ring), 
V represents O or S, 
Y.sup.1 represents hydrogen, C.sub.1 -C.sub.4 -alkyl, chlorine, 
C.sub.1 -C.sub.4 -alkoxy, C.sub.1 -C.sub.4 -alkoxycarbonyl, C.sub.1 
-C.sub.4 -alkylsulphonyl, phenyl or cyclohexyl, 
Y.sup.2 represents hydrogen, methyl or chlorine and 
Y.sup.3 represents hydrogen, C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.2 
-alkoxy or chlorine, and wherein 
Z.sup.1 and Z.sup.4 and Z.sup.2 and Z.sup.3 together can represent a 
radical of the formula --(CH.sub.2).sub.3 --. 
Dimethine dyestuffs of the formula 
##STR6## 
wherein T.sup.1 and T.sup.2 each by itself represents C.sub.1 -C.sub.4 
-alkyl or phenyl-C.sub.1 -C.sub.3 -alkyl, 
Q represents a radical of the formula 
##STR7## 
W represents O, S, NH or NH--CO (CO on the aromatic ring) and T.sup.3 
represents hydrogen, methyl, methoxy, ethoxy or chlorine, have a 
particular industrial value. 
Compounds of the formula V in which W=0, are particularly preferred. 
The invention furthermore relates to a process for the preparation of the 
dimethane dyestuffs of the formula I. The process is characterised in that 
aldehydes of the formula 
##STR8## 
wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 have the abovementioned 
meaning, 
or functional derivatives of these aldehydes, are subjected to a 
condensation reaction with cyanomethyl compounds of the formula 
##STR9## 
wherein A and B have the abovementioned meaning. 
The condensation can be carried out under the customary reaction 
conditions, such as are described, for example, in U.S. Pat. No. 4,105,665 
in an inert organic solvent in the presence of a basic catalyst. 
Compounds which are usually employed in the Knoevenagel reaction, such as, 
for example, ammonia, sodium acetate, potassium carbonate, potassium 
hydroxide, potassium cyanide, sodium methylate, sodium ethylate or organic 
nitrogen bases, such as diethylamine, dimethylamine, pyridine or 
morpholine, can be used as the basic catalysts. Preferred catalysts are 
piperidine, pyrrolidine and piperidine acetate. 
Possible inert organic solvents are both polar solvents and non-polar 
solvents, it being expedient, if water-immiscible solvents are used, for 
the water formed during the reaction to be removed from the reaction 
mixture by azeotropic distillation. 
Solvents which are used are, for example: alcohols, such as methanol, 
ethanol, isopropanol, n-propanol, n-butanol, cyclohexanol, benzyl alcohol, 
.beta.-phenethyl alcohol, glycol, glycol monomethyl ether, glycol 
monoethyl ether and .beta.-dimethylaminoethanol; amides, such as 
formamide, dimethylformamide, dimethylacetamide and N-methylpyrrolidone; 
dimethylsulphoxide; acetonitrile, dioxane and tetrahydrofuran; and 
water-immiscible solvents, such as benzene, toluene, xylene or 
chlorobenzene. 
The reaction temperatures can be varied within a wide range, for example 
from 15.degree. to 150.degree. C. 
The starting compounds of the formula VIII and functional derivatives 
thereof are known (DE-OS (German Published Specification) No. 2,413,281). 
Particularly suitable functional derivatives of these aldehydes are the 
compounds first obtained in the preparation of the aldehydes by the 
Vilsmeier reaction, that is to say the compound obtained before hydrolysis 
to give the aldehyde, and in particular those which are characterised by 
the part structure 
##STR10## 
wherein 
An.sup..crclbar. denotes an anion, such as PO.sub.2 Cl.sub.2.sup..crclbar. 
or Cl.sup..crclbar.. 
The starting compounds of the formula IX are likewise known (DE-AS (German 
Published Specification) Nos. 1,201,354, 1,207,937, 2,005,933, 2,327,959, 
2,632,402 and 2,710,285. 
A second process for the preparation of compounds of the formula (I) is 
characterised in that salicylaldehydes of the formula 
##STR11## 
wherein 
R.sup.1 -R.sup.4 have the meaning indicated above are subjected to a 
condensation reaction with compounds of the formula 
##STR12## 
wherein A and B have the meaning indicated above and E represents the 
carboxylic acid ester group, the carboxylic acid amide group or the 
nitrile group with closure of the coumarin ring. Appropriate carboxylic 
acid ester groups are above all C.sub.1 -C.sub.4 alkyl esters. 
The condensation reaction can be carried out in an inert solvent in the 
presence of a basic catalyst under similar conditions as indicated for the 
above process. 
The starting compounds of the formula XII are known. The starting compounds 
of the formula XIII are for example prepared by subjecting compounds of 
the formula IX to a condensation reaction with formylacetic acid 
derivatives of the formula 
##STR13## 
wherein 
E has the same meaning as in formula XIII or with derivatives of XIV in 
which the formyl group is functionally modified. 
This condensation reaction is also carried out under the customary basic 
conditions in one of the above-mentioned inert solvents. 
Formylacetic esters, which are in the form of alkali metal salts, may 
advantageously be subjected to a condensation reaction in a mixture of a 
polar, water-miscible inert solvent such as ethanol, and also in the 
presence of water. 
The dimethine dyestuffs of the formula I are suitable for dyeing and 
printing natural, semi-synthetic and synthetic fibre materials and 
fabrics, for example fibres of polyester, polyamide, polyurethane, 
cellulose 21/2-acetate, cellulose triacetate, polypropylene and 
polyacrylonitrile. 
Very clear dyeings which have luminous-red shades and are distinguished by 
good fastness properties in use and by a high brilliance are obtained on 
the fibres and fabrics mentioned, in particular on polyester, with the 
dyestuffs of the formula I according to the invention. 
The warning and signal orange shade RAL 2005 (with a luminous factor 
.beta..gtoreq.0.45 according to DIN 16,954) laid down by the German 
Standards Sub-Committee for Terms of Delivery and Quality Assurance can 
advantageously be established by mixing or combining the dyestuffs 
according to the invention with known 7-di-C.sub.1 -C.sub.4 
-alkyl)-amino-3-heteryl-coumarin dyestuffs, in which heteryl represents a 
benzoxazole, benzothiazole, benzimidazole, quinazolone or 
5-phenyl-1,3,4-thiadiazole radical which is optionally substituted e.g. by 
1 or 2 C.sub.1 -C.sub.4 -alkyl radicals, 1 or 2 chlorine atoms, C.sub.1 
-C.sub.4 -alkoxy, C.sub.1 -C.sub.4 -alkylsulphonyl, C.sub.1 -C.sub.4 
-alkoxycarbonyl, cyclohexyl or phenyl (DE-AS (German Published 
Specification) Nos. 1,098,125, 1,469,770, 2,005,933, 2,030,507, 2,126,811 
and 2,529,434) or with 10-(C.sub.1 -C.sub.2 
-alkoxy)-benzo[k,1]xanthene-3,4-dicarboxylic acid imides, such as are 
described in DE-AS (German Published Specification) Nos. 1,569,761 and 
1,770,818. This shade is of industrial importance for the production of 
warning clothing, warning and signal signs and sports articles. Such 
articles with the colour shade RAL 2005 have hitherto been produced 
exclusively by direct application of a polyamide or polyurethane coating 
in which fluorescent pigments are embedded to cotton fabric. The 
disadvantages of inadequate abrasion-resistance and very low fastness to 
light of the pigment coating are overcome by dyeing hydrophobic fibre 
materials directly with the above-mentioned mixture or combination. 
The dimethine dyestuffs of the formula I are also particularly suitable for 
colouring plastic compositions, in particular polycarbonate. In these the 
high heat stability of the compounds of the good light fastness of the 
fluorescence should be emphasized. 
The fluorescent luminous-red dyestuffs of the formula I can also 
advantageously be used, in a very pure form, as laser dyestuffs and as 
energy converter in light-collecting systems. 
0.001 to 0.01% colourings, especially 0.01% colourings of pure dyestuffs of 
the formula I, in particular Example 2, are particularly suitable in 
polycarbonate, such as .sup.(R) MAKROLON. 
The light collectors can be used with or without additional electronic 
structural elements.