Process for the manufacture of coumarin dyes

A process for the manufacture of coumarin dyes of the formula ##STR1## wherein Y represents a sulphur or an oxygen atom and the ring B can carry non-ionogenic substituents or substituted or unsubstituted fused rings, and A represents a hydrogen atom, a hydroxyl, alkoxy or phenoxy group, a nitrogen-containing heterocyclic ring system which is fused to two carbon atoms or represents a group --NR.sub.1 R.sub.2, in which R.sub.1 represents a substituted or unsubstituted alkyl or phenyl group, R.sub.2 represents a hydrogen atom or has one of the meanings assigned to R.sub.1, or R.sub.1 and R.sub.2 together with the nitrogen atom to which they are attached represent a 5- or 6-membered ring system, which process comprises condensing heterocyclic products of the formula ##STR2## wherein R represents a --CN--, --COOR' or ##STR3## group, in which R' represents a substituted or unsubstituted alkyl or aryl group and each of R" and R'" independently can be the same as R' or a hydrogen atom, or together with the nitrogen atom to which they are attached form a heterocyclic 5- or 6-membered ring, and Y and B are as defined above, with the proviso that, if Y represents a sulphur atom, the reaction mixture consisting of malodinitrile and o-aminothiophenols is used as starting material, in the presence of an organic solvent and a catalytic amount of a strong acid, with an aldehyde of the formula ##STR4## wherein A is as defined above.

The invention provides a process for the manufacture of fluorescing 
coumarin dyes which comprises condensing heterocyclic products of the 
formula 
##STR5## 
wherein R represents a --CN, --COOR' or 
##STR6## 
group, in which R' represents a substituted or unsubstituted alkyl or aryl 
group and each of R" and R'" independently can be the same as R' or a 
hydrogen atom or together with the nitrogen atom to which they are 
attached form a heterocyclic 5- or 6-membered ring, Y represents a sulphur 
or an oxygen atom and the ring B can carry non-ionogenic substituents or 
substituted or unsubstituted fused rings, in the presence of an organic 
solvent and a catalytic amount of a strong acid, with an aldehyde of the 
formula 
##STR7## 
which is substituted in the ortho-position and wherein A represents a 
hydrogen atom, a hydroxyl, alkoxy or phenoxy group, a nitrogen-containing 
heterocyclic ring which is fused to two carbon atoms, or preferably 
represents a group --NR.sub.1 R.sub.2, in which R.sub.1 represents a 
substituted or unsubstituted alkyl or phenyl group, R.sub.2 represents a 
hydrogen atom or has one of the meanings assigned to R.sub.1, or R.sub.1 
and R.sub.2 together with the nitrogen atom to which they are attached 
represent a heterocyclic 5- or 6-membered ring system, to give the 
coumarin dye of the formula 
##STR8## 
wherein A, Y and B are as defined above, with the proviso that, if Y 
represents a sulphur atom, the reaction mixture consisting of malodinitile 
and o-aminothiophenols can be used as starting material. 
All the alkyl groups in the molecule preferably contain 1, 2, 3 or 4 carbon 
atoms and can carry as substituents for example one or more halogen atoms, 
by which are meant here in general especially chlorine or bromine atoms, 
lower alkoxy groups (for example methoxy, ethoxy, propoxy, butoxy groups), 
hydroxyl groups, cyano, vinyl, amino, lower alkylamino, phenyl, phenoxy, 
acyl, acyloxy or acylamino groups. Unsubstituted methyl and ethyl groups 
are particularly preferred. 
All phenyl groups in the molecule, and also the phenyl nucleus B, can carry 
the substituents referred to above and, for example, in addition alkyl and 
nitro groups. 
A heterocyclic ring system represented by R.sub.1 and R.sub.2 together with 
the nitrogen atom to which they are attached is to be understood as 
meaning in general a 5- or 6-membered ring which (as described above) is 
substituted for unsubstituted and which, in addition to the .dbd.CH and 
--CH.sub.2 groups, can contain further heteroatoms, in particular sulphur 
or nitrogen atoms as well as substituents, and can be saturated, 
unsaturated or of aromatic character. Such a ring is chiefly the 
piperidine, piperazine, N-acylpiperazine (such as N-acetyl- or 
N-formylpiperazine), pyrrolidine, morpholine and N-alkylpiperazine (such 
as N-methylpiperazine or N-ethylpiperazine) ring. 
Preferred acyl groups are those of the formula R.sub.3 --Y'-- or R.sub.3 
--Z--, wherein R.sub.3 represents a hydrocarbon radical which can carry 
the substituents referred to above and/or heteroatoms, preferably a 
substituted or unsubstituted alkyl or phenyl group. Y' represents a 
radical --O--CO--, --SO.sub.2 -- or --O--SO.sub.2 --, Z represents a 
radical --CO--, --NR.sub.4 CO-- or --NR.sub.4 SO.sub.2 --, wherein R.sub.4 
represents a hydrogen atom or has the meaning assigned to R.sub.3. 
The manufacture of compounds of the formula 
##STR9## 
is of particular interest, wherein R.sub.1 represents an alkyl group of 1 
to 4 carbon atoms which can be substituted by hydroxyl, vinyl, cyano, 
alkoxy, formyloxy, alkylcarbonyloxy, alkoxycarbonyloxy or alkoxycarbonyl, 
and R.sub.2 represents a hydrogen atom or has one of the meanings assigned 
to R.sub.1, while suitable values for R.sub.1 and R.sub.2 are in 
particular methyl, ethyl, propyl, butyl, alkyl, .beta.-chloroethyl, 
.gamma.-chloro-.beta.-hydroxypropyl, .beta.-hydroxyethyl, 
.beta.-cyanoethyl, .gamma.-cyanopropyl, .beta.-methoxyethyl, 
.beta.-acetoxyethyl, .beta.-butyryloxyethyl, methoxycarbonylethyl, 
ethoxycarbonylethyl, phenylethyl or benzyl, and Y is as defined above. 
The term "lower" whenever used herein in connection with definitions such 
as alkyl, alkoxy, carbalkoxy etc., denotes that the alkyl moieties 
occurring in the radical contain from 1 to 4 carbon atoms. 
The starting products are themselves known. As examples of such compounds 
there may be mentioned: benzoxazolyl acetonitrile, benzoxazolyl acetate, 
benzoxazolyl acetamide, methylbenzoxazolyl acetonitrile, 
dimethylbenzoxazolyl acetonitrile, chlorobenzoxazolyl acetonitrile, 
tert.-butylbenzoxazolyl acetonitrile, phenylbenzoxazolyl acetonitrile, 
naphthoxazolyl acetonitrile, cyanoethylbenzoxazolyl acetonitrile, 
ethoxycarbonylethylbenzoxazolyl acetonitrile, 
ethoxycarbonylmethylbenzoxazolyl acetonitrile, nitrobenzoxazolyl 
acetonitrile, dichlorobenzoxazolyl acetonitrile, methylbenzoxazolyl 
acetate, benzthiazolyl acetonitrile, chlorobenzthiazolyl acetonitrile, 
dichlorobenzthiazolyl acetonitrile, methylbenzthiazolyl acetonitrile, 
dimethylbenzthiazolyl acetonitrile, nitrobenzthiazolylacetonitrile, 
chloromethylbenzthiazolyl acetonitrile, naphthiazolyl acetonitrile, 
benzthiazolyl acetate, methylbenzthiazolyl acetate and benzthiazolyl 
acetamide. 
Suitable solvents are all solvents which are stable to acids. On the one 
hand it is possible to use watermiscible solvents, for example alcohols 
(methanol, ethanol, isopropyl alcohol), for example dioxane, 
methoxyethanol, ethoxyethanol, 1,2-dimethoxyethane, dimethyl formamide, 
tetramethyl urea, sulpholane (tetramethylene sulphur dioxide), 
tris(dimethylamino)-phosphate, dimethyl sulphoxide. Mixtures of the 
aforementioned solvents can also be used. On the other hand it is also 
possible to use water-immiscible solvents, such as benzene, toluene or 
xylene, aliphatic and aromatic chlorinated hydrocarbons, such as carbon 
tetrachloride, trichloroethylene, ethylene chloride, methylene chloride, 
chloroform, trichloroethane, tetrachloroethane, perchloroethylene, mono- 
or dichlorobenzene. 
When using water-immiscible solvents, two-phase mixtures are obtained when 
an aqueous acid, for example aqueous hydrochloric acid, is added. 
The amount of solvent used as reaction medium depends on the respective 
reaction substrate and is chosen solely in accordance with technical (for 
example good stirribility) and economic (good space-time yields) aspects. 
The condensation of compounds I and II is carried out at temperatures 
between 0.degree. and 100.degree. C., preferably between 20.degree. and 
70.degree. C. As a rule as low a temperature as possible will be chosen. 
Suitable acid catalytics are primarily mineral acids, such as hydrohalic 
acids, sulphuric acid and phosphoric acid, and also strong organic acids, 
such as formic acid, acetic acid or chloroacetic acid. Preferably aqueous 
hydrochloric acid is used. If compounds of the formula I, in which R 
represents a cyano or amide group, are used as starting materials, then it 
is necessary to add the requisite stoichiometric amount of acid to 
neutralise the ammonia or amine which is set free during the condensation 
with the aldehyde of the formula (II). 
Particularly preferred starting materials and intermediates are those which 
are derived from aminothiophenols and give benzthiazolyl compounds, i.e. 
those in which Y is a sulphur atom. 
Exceptionally good yields of the heterocyclic products of the formula (I), 
which can be further condensed direct without isolation to give the dyes 
of the formula (III), are obtained in particular from malonic dinitrile 
and o-aminothiophenols. It is therefore possible to obtain the dyes of the 
formula (III) which contain a benzthiazolyl group direct and in good yield 
by carrying out the reaction in two steps consecutively in the same 
reaction vessel. The partial steps described above and the last mentioned 
combined two-step reaction constitute particularly preferred embodiments 
of the invention for which protection is sought. 
The dyestuffs obtained according to the instant process are valuable 
disperse dyestuffs which give fast yellow shades on polyester fibers.

The invention is illustrated by the following Examples, in which the parts 
and percentages are by weight unless otherwise stated. 
EXAMPLE 1 
3.4 Parts of 2-cyanomethyl-5-methylbenzoxazole and 3.9 parts of 
diethylaminosalicyl aldehyde in 22 parts of methanol are treated at room 
temperature with 3.7 parts of conc. hydrochloric acid. The mixture is 
stirred for 4 hours at 67.degree. C., buffered with sodium acetate and 
further stirred for 1 hour. After cooling, filtration, and drying, 3.2 
parts of a dye of the formula 
##STR10## 
are obtained, which dyes polyester fibres in yellow shades. 
EXAMPLE 2 
4.8 Parts of diethylaminosalicyl aldehyde and 4.4 parts of benzthiazolyl 
acetonitrile in 25 parts of methanol are treated at room temperature with 
4.5 parts of conc. hydrochloric acid. The mixture is stirred for 31/2 
hours at 65.degree. C. to 70.degree. C. are subsequently treated with 2 
parts of sodium acetate crystals. After stirring for a further hour at 
65.degree. to 70.degree. C., the suspension is cooled to room temperature 
and filtered. The residue is washed firstly with methanol, then with 
water, and dried to yield 8.4 parts of a dye of the formula 
##STR11## 
which dyes polyester fibres in yellow shades. 
EXAMPLE 3 
4.8 Parts of diethylaminosalicyl aldehyde and 4.4 parts of benzthiazolyl 
acetonitrile are suspended in 30 parts of chlorobenzene and the suspension 
is treated with 17 parts of conc. hydrochloric acid. After the mixture has 
been stirred for 3 hours at 90.degree. C., it is cooled and filtered. The 
residue is washed neutral with water and dried to yield 7.3 parts of the 
same dye as that obtained in Example 2. 
The same dye is also obtained by using benzthiazolyl acetate or 
benzthiazolyl acetamide instead of benzthiazolyl acetonitrile. 
EXAMPLE 4 
1.65 Parts of malodinitrile in 25 parts of methanol are treated with one 
drop of aqueous ammonia and, under nitrogen, with 3.1 parts of 
o-aminothiophenol at a maximum temperature of 30.degree. C. After the 
mixture has been stirred for 1 hour at room temperature, it is neutralised 
at a maximum temperature of 30.degree. C. with 2.5 parts of conc. 
hydrochloric acid and thereafter treated with 4.8 parts of 
diethylaminosalicyl aldehyde. After addition of a further 4.5 parts of 
conc. hydrochloric acid, the mixture is heated for 31/2 hours to 
65.degree. to 70.degree. C. and then 2 parts of sodium acetate crystals 
are added. After stirring for a further hour at 65.degree. to 70.degree. 
C., the mixture is cooled and filtered. The residue is washed with water 
and dried and consists of 7.6 parts of the dye of the formula