The novel benzimidazoles have the formula ##STR1## in which A is the radical ##STR2## R.sub.1 is cyanomethyl, 1-cyanoethyl or, if n is the number 1, also 2-cyanoethyl or C.sub.3-6 -carboalkoxymethyl, R.sub.2 is C.sub.1-4 -alkyl or C.sub.3-4 -alkenyl, R.sub.3 is cyanomethyl, cyanoethyl or C.sub.3-6 -carboalkoxymethyl, R.sub.4 and R.sub.5 independently of one another are hydrogen or chlorine, X.sup..crclbar. is a colorless anion of an organic or inorganic acid and n is the number 0 or 1. They are used for the fluorescent brightening of organic materials.

The present invention relates to novel benzimidazoles which are 
unsubstituted on the benzo ring, to processes for their preparation and to 
their use for the fluorescent brightening of organic materials. 
U.S. Pat. Nos. 3,637,734 and 4,009,994 and British Pat. No. 1,313,332 
disclose the particularly readily accessible benzimidazoles which are 
unsubstituted on the benzo ring of the benzimidazole radical, but which 
produce unsatisfactory white effects. The non-quaternised representatives 
do not achieve high maximum effects. The quaternised or non-quaternised 
representatives which are unsubstituted on the benzo ring of the 
benzimidazole radical do not enable high white effects to be achieved. 
It was therefore the object of the present invention to discover 
benzimidazoles which are unsubstituted on the benzo ring of the 
benzimidazole radical and which do not exhibit these drawbacks. 
It has now been found that surprisingly high white effects can be achieved 
by means by some selected benzimidazoles which are unsubstituted on the 
benzo ring of the benzimidazole radical. 
The novel benzimidazoles according to the invention have the formula 
##STR3## 
in which A is the radical 
##STR4## 
R.sub.1 is cyanomethyl, 1-cyanoethyl or, if n is the number 1, also 
2-cyanoethyl or C.sub.3-6 -carboalkoxymethyl, R.sub.2 is C.sub.1-4 -alkyl 
or C.sub.3-4 -alkenyl, R.sub.3 is cyanomethyl, cyanoethyl or C.sub.3-6 
-carboalkoxymethyl, R.sub.4 and R.sub.5 independently of one another are 
hydrogen or chlorine, X.sup..crclbar. is a colourless anion of an organic 
or inorganic acid and n is the number 0 or 1. 
"C.sub.3-6 -Carboalkoxymethyl" is to be understood as meaning the radicals 
C.sub.4 H.sub.9 OOCCH.sub.2 --, C.sub.3 H.sub.7 OOCCH.sub.2 --, isomers 
thereof and, in particular, C.sub.2 H.sub.5 OOCCH.sub.2 -- and CH.sub.3 
OOCCH.sub.2 --. 
Compounds of the formula (1) in which n is 0 can also be in the form of 
acid adducts and can be used for fluorescent brightening. 
A suitable anion X.sup..crclbar. is any colourless anion of an organic or 
inorganic acid. Its nature has no essential influence on the fluorescent 
brightening properties of the compounds according to the invention. As a 
rule, the anion is introduced by the process of preparation 
(quaternisation or protonation), but it can also be replaced by another 
anion by known methods (see, for example, Houben-Weyl, Methoden der 
organischen Chemie ("Methods of Organic Chemistry"), Volume XI/2, pages 
620-626). Anions of halogens can also be replaced in accordance with U.S. 
Pat. No. 4,095,943 by anions of aliphatic carboxylic acids by reacting the 
halide in the presence of these carboxylic acids using epoxides as 
hydrogen halide acceptors. 
Within the scope of the compounds of the formula (1), those of the formula 
##STR5## 
in which A' is the radical 
##STR6## 
R.sub.2 ' is C.sub.1-4 -alkyl and R.sub.1, R.sub.3, X.sup..crclbar. and n 
have the meaning indicated above, should be singled out. R.sub.2 ' is 
preferably methyl. 
Within the scope of the compounds of the formulae (1) and (2), those of the 
formula 
##STR7## 
in which A" is the radical 
##STR8## 
or, if n is the number 1, also the radical 
##STR9## 
those of the formula 
##STR10## 
in which A'" is the radical 
##STR11## 
R.sub.1 ' and R.sub.3 ' independently of one another are cyanomethyl, 
cyanoethyl or C.sub.3-8 -carboalkoxymethyl, in which formulae R.sub.1, 
R.sub.2 ', R.sub.3, R.sub.4, X.sup..crclbar. and n have the meaning 
indicated above, and those of the formula 
##STR12## 
in which R.sub.1 " is cyanoethyl or C.sub.3-4 -carboalkoxymethyl and 
X.sup..crclbar. has the meaning indicated above, deserve special mention, 
R.sub.1 ' is preferably identical with R.sub.3 '. 
Compounds of practical interest are those of the formula 
##STR13## 
in which X.sup..crclbar. is a colourless anion of an organic or inorganic 
acid, 
##STR14## 
in which X.sub.1 is chlorine or bromine, and 
##STR15## 
The benzimidazoles of the formula (1) are prepared by converting a 
benzimidazole of the formula 
##STR16## 
in a first stage, in the presence of a base, by means of at least one mol 
equivalent of an alkylating agent R.sub.1 X or by means of acrylonitrile, 
into a benzimidazole of the formula 
##STR17## 
and, if desired, with or without previously isolating this compound, 
quaternising it in a second phase with a compound of the formula R.sub.3 
X, A, R.sub.1, R.sub.3 and X in the above formulae having the meanings 
indicated above. 
In the case of compounds of the formula (1) in which R.sub.1 =R.sub.3, the 
alkylation and quaternisation can advantageously be carried out 
simultaneously, i.e. without isolating the compound of the formula (11). 
Suitable bases are, in particular, alkali metal salts and alkaline earth 
metal salts of weak acids, such as sodium carbonate, potassium carbonate 
or calcium carbonate, or alkaline earth metal oxides, such as magnesium 
oxide, in a finely divided form. Tertiary amines which are difficult to 
quaternise, such as triisopropanolamine or 2,6-di-tert.-butylpyridine, are 
also suitable as acid acceptors. 
A particular advantageous procedure is first to convert the benzimidazole 
of the formula (10) which is unsubstituted on the nitrogen, by means of 
strong alkalis, such as alkali metal hydroxides or alkali metal 
alcoholates, for example sodium hydroxide or sodium ethylate or potassium 
hydroxide or potassium ethylate, into the corresponding N-alkali metal 
salts, and then to alkylate the latter. 
The alkylation or quaternisation is advantageously effected in a direct 
manner by warming in excess alkylating agent or in an inert solvent, at 
temperatures between 20.degree. and 150.degree. C., preferably 50.degree. 
and 140.degree. C., depending on the reactivity of the alkylating agent 
used. 
In general, suitable reaction media in which the quaternisation can be 
carried out are any inert solvents. Preferred solvents are those which 
dissolve the starting material and from which the end product is 
precipitated immediately. The following may be mentioned as examples: 
aromatic hydrocarbons, such as benzene, toluene and xylene; halogenated 
hydrocarbons, such as trichloroethane, tetrachloroethylene, chlorobenzene 
or dichlorobenzene, and also nitro compounds, such as nitromethane, 
nitropropane or nitrobenzene, alkanols and open or cyclic ethers, such as 
butanol, dibutyl ether, ethylene glycol, ethylene glycol monomethyl ether, 
ethylene glycol monoethyl ether, anisole or dioxane; ketones, such as 
cyclohexanone or methyl ethyl ketone; fatty acid amides, such as 
dimethylformamide or dimethylacetamide; sulfoxides, such as dimethyl 
sulfoxide, and carboxylic acid esters, such as ethyl acetate or butyl 
acetate. 
Quaternary compounds of the formula (1), i.e. those in which n is 1, are 
also obtained by reacting equivalent quantities of a coumarilyl halide or 
a phenyl-furane-carboxylic acid halide with N,N'-disubstituted 
o-phenylenediamines, for example N,N'-di-cyanoalkyl-o-phenylenediamines 
and N,N'-di-carboalkoxyalkyl-o-phenylenediamines. This process is 
particularly suitable for compounds of the formula (1) in which R.sub.1 
and R.sub.3 are 2-cyanoethyl. 
It is advantageous to carry out the reaction in inert solvents such as 
indicated above and/or in the presence of tertiary bases, such as pyridine 
or triethylamine, at temperatures between 20.degree. and 150.degree. C., 
preferably 50.degree. and 140.degree. C. For example, the compounds of the 
formula 
##STR18## 
are prepared by this process by reacting a compound of the formula 
##STR19## 
with a compound of the formula 
##STR20## 
in which X.sub.1 is halogen and R.sub.1 and R.sub.2 have the meanings 
indicated above. Preferred halogens are chlorine and bromine. 
Compounds of the formula (1) in which A is alkoxybenzofuranyl or 
alkenyloxybenzofuranyl can also be prepared by subjecting a 
salicylaldehyde of the formula 
##STR21## 
in which R.sub.2 has the meaning indicated above, to a condensation 
reaction, in the presence or absence of a basic condensation agent, with a 
halogenomethylbenzimidazole of the formula 
##STR22## 
in which R.sub.1, R.sub.3, X.sup..crclbar. and n have the meanings 
indicated above and Hal is fluorine, chlorine or bromine. 
Suitable basic condensation agents are inorganic and organic compounds, 
such as alkali metal compounds and alkaline earth metal compounds, for 
example oxides, alcoholates, carbonates, bicarbonates or acetates, 
ammonium compounds, for example ammonium acetate, or tertiary amines, such 
as pyridine. It is preferable to use inorganic compounds of sodium and 
potassium, preferably carbonates thereof. However, it is also possible to 
use mixtures of various weakly basic compounds. 
The quantity of condensation agent to be employed varies within wide 
limits. Although a catalytic quantity is adequate for the success of the 
reaction itself, it is advantageous to use equivalent quantities or even a 
multiple thereof. 
It is advantageous to carry out the condensation reaction in a solvent 
which is inert under the reaction conditions. Suitable solvents of this 
type are apolar and dipolar aprotic solvents, such as xylene, 
dichlorobenzene, trichlorobenzene, dimethylformamide, diethylformamide, 
dimethylacetamide or N-methylpyrrolidone or mixtures thereof. It is 
preferable to use anhydrous organic solvents in which the base used is 
partly or completely soluble. 
In certain cases, for example if the starting materials have low melting 
points and do not decompose, it is also possible to carry out the reaction 
according to the invention in the presence of the weakly basic 
condensation agent without a solvent, i.e. in the melt. 
Depending on the process (with or without a solvent) and the compounds to 
be subjected to a condensation reaction, the reaction temperature can vary 
within a wide range. If solvents are used, it is between 50.degree. C. and 
the boiling point of the particular solvent, preferably, however, between 
50.degree. and 200.degree. C., and particularly between 90.degree. and 
160.degree. C. If the condensation reaction is carried out without a 
solvent, the reaction temperature is then between the melting point of the 
mixture of reactants used and the decomposition temperature of the 
compounds to be subjected to the condensation reaction. Suitable 
temperatures are preferably between 100.degree. and 250.degree. C. 
Preferred anions X.sup..crclbar. are halides, such as chlorides or 
bromides, and also tosylates. If desired, the anion can be replaced by 
another anion in accordance with known methods (c.f., for example, 
Houben-Weyl, Methoden der organischen Chemie ("Methods of Organic 
Chemistry"), Volume XI/2, pages 620-626). In this case, preferred anions 
are anions of formic acid, acetic acid, propionic acid, glycollic acid, 
lactic acid, malic acid, tartaric acid, mucic acid, gluconic acid, citric 
acid, laevulinic acid, acrylic acid, methanephosphonic acid and monoalkyl 
esters thereof and of dialkyl esters of phosphoric acid. 
The compounds of the formulae (10), (13), (14), (15) and (16) are known or 
can be prepared by methods which are known per se (c.f., for example, U.S. 
Pat. Nos. 3,637,734, British Pat. No. 1,313,332 and German 
Offenlegungsschriften Nos. 2,853,765 and 2,904,829). 
The novel compounds defined above exhibit a more or less pronounced 
fluorescence in the dissolved or finely dispersed state. They can be used 
for the fluorescent brightening of a very wide variety of synthetic, 
semi-synthetic or natural organic materials or substances which contain 
such organic materials. 
The following groups of organic materials, where fluorescent brightening 
thereof is relevant, may be mentioned as examples of the above, without 
the list given below being intended to express any restriction thereto; 
I. Synthetic organic materials of high molecular weight: 
(a) Polymerisation products based on organic compounds containing at least 
one polymerisable carbon-carbon double bond, i.e. their homopolymers or 
copolymers as well as their after-treatment products, for example 
crosslinking, grafting or degradation products, polymer blends, or 
products obtained by modification of reactive groups, for example polymers 
based on .alpha.,.beta.-unsaturated carboxylic acids or derivatives of 
such carboxylic acids, especially on acrylic compounds (for example 
acrylates, acrylic acid, acrylonitrile, acrylamides and their derivatives 
or their methacrylic analogues), on olefin hydrocarbons (for example 
ethylene, propylene, styrenes or dienes and also so-called ABS polymers) 
and polymers based on vinyl and vinylidene compounds (for example vinyl 
chloride, vinyl alcohol and vinylidene chloride), 
(b) Polymerisation products which can be obtained by ring opening, for 
example polyamides of the polycaprolactam type, and also polymers which 
are obtainable either by polyaddition or by polycondensation, such as 
polyethers or polyacetals, 
(c) Polycondensation products or precondensates based on bifunctional or 
polyfunctional compounds with condensable groups, the homocondensation and 
co-condensation products, and after-treatment products thereof, for 
example polyesters, in particular saturated polyesters (for example 
polyesters of ethylene glycol/terephthalic acid) or unsaturated polyesters 
(for example maleic acid/dialcohol polycondensates and their crosslinking 
products with copolymerisable vinyl monomers), unbranched and branched 
polyesters (also including those based on polyhydric alcohols, for example 
alkyd resins), polyamides (for example hexamethylenediamine adipate), 
maleic resins, melamine resins, the precondensates and analogues thereof, 
polycarbonates and silicones, 
(d) Polyaddition products, suc as polyurethanes (crosslinked and 
uncrosslinked). 
II. Semi-synthetic organic materials, for example cellulose esters of 
varying degrees of esterification (so-called 21/2-acetate or triacetate) 
or cellulose ethers, regenerated cellulose (viscose or cuprammonium 
cellulose), or their after-treatment products, and casein plastics 
III. Natural organic materials of animal or vegetable origin, for example 
based on cellulose or proteins, such as cotton, wool, linen, silk, varnish 
gums, starch and casein. 
The organic materials which are to undergo fluorescent brightening can be 
in the most diverse states of processing (raw materials, semi-finished 
goods or finished goods). On the other hand, they can be in the form of 
structures of the most diverse shapes, for example predominantly 
three-dimensional structures, such as sheets, profiles, injection 
mouldings, various machined articles, chips, granules or foams, and also 
predominantly two-dimensional structures, such as films, foils, lacquers, 
coverings, impregnations and coatings, or predominantly one-dimensional 
bodies, such as filaments, fibres, flocks and wires. The said materials 
can, on the other hand, also be in an unshaped state, in the most diverse 
homogeneous or inhomogeneous forms of division, for example in the form of 
powders, solutions, emulsions, dispsersions, lactices, pastes or waxes. 
Fibre materials can be, for example, in the form of endless filaments 
(stretched or unstretched), staple fibres, flocks, hanks, textile 
filaments, yarns, threads, non-wovens, felts, waddings, flocked structures 
or woven textile or bonded textile fabrics, knitted fabrics and papers, 
cardboards or paper pulps. 
The compounds to be used in accordance with the invention are of 
importance, inter alia, for the treatment of organic textile materials, 
especially woven textile fabrics. If fibres, which can be in the form of 
staple fibres or endless filaments or in the form of hanks, woven fabrics, 
knitted fabrics, non-wovens, flocked substrates or bonded fabrics, are to 
be subjected to fluorescent brightening according to the invention, this 
is advantageously effected in an aqueous medium in which the particular 
compounds are present in a finely divided form (suspensions, so-called 
microdispersions, or, where appropriate, solutions). If desired, 
dispersing agents, stabilisers, wetting agents and further assistants can 
be added during the treatment. 
Depending on the type of fluorescent brightening compound used, it can 
prove advantageous to apply the compounds in a neutral, alkaline or acid 
bath. The treatment is usually carried out at temperatures below about 
20.degree. and 140.degree. C., for example at the boiling point of the 
bath or near it (about 90.degree. C.). Solutions or emulsions in organic 
solvents can also be used for the finishing, according to the invention, 
of textile substrates, as is practised in the dyeing industry in so-called 
solvent dyeing (pad-thermofixation, or exhaust dyeing processes in dyeing 
machines). 
The novel fluorescent brightening agents of the present invention can 
further be added to or incorporated in the materials before or during 
their shaping. Thus, for example, they can be added to the compression 
moulding composition or injection moulding composition during the 
production of films, sheets (for example incorporated in polyvinyl 
chloride in a roll mill at elevated temperature) or mouldings. 
If the shaping of man-made fully synthetic or semi-synthetic organic 
materials is effected by spinning processes or from spinning 
solutions/melts, the fluorescent brightening agents can be applied by the 
following processes: 
addition to the starting substances (for example monomers) or intermediates 
(for example precondensates or prepolymers), i.e. before or during the 
polymerisation, polycondensation or polyaddition, 
sprinkling in powder form on polymer chips or granules for spinning 
solutions/melts, 
bath dyeing of polymer chips or granules for spinning solutions/melts, 
metered addition to spinning melts or spinning solutions and application to 
the spun tow before stretching. 
The novel fluorescent brightening agents of the present invention can, for 
example, also be employed in the following use forms: 
(a) in mixtures with dyestuffs (shading) or pigments (coloured pigments or 
especially, for example, white pigments), or as an additive to dyebaths, 
printing pastes, discharge pastes or reserve pastes, or for the 
after-treatment of dyeings, prints or discharge prints, 
(b) in mixtures with carriers, wetting agents, plasticizers, swelling 
agents, antioxidants, light stabilisers, heat stabilisers and chemical 
bleaching agents (chlorite bleach or bleaching bath additives), 
(c) in admixture with crosslinking agents or finishing agents (for example 
starch or synthetic finishes), and in combination with a wide variety of 
textile finishing processes, especially synthetic resin finishes (for 
example creaseproof finishes such as "wash-and-wear", "permanent press" or 
"non-iron"), as well as flameproof finishes, soft-handle finishes, 
anti-soiling finishes or antistatic finishes, or antimicrobial finishes, 
(d) incorporation of the fluorescent brightening agents into polymeric 
carriers (polymerisation, polycondensation or polyaddition products) in 
dissolved or dispersed form, for use, in example, in coating agents, 
impregnating agents or binders (solutions, dispersions and emulsions) for 
textiles, non-wovens, paper and leather, 
(e) as additives to master batches, 
(f) as additives to a wide variety of industrial products in order to 
render these more marketable (for example improving the appearance of 
soaps, detergents and pigments), 
(g) in combination with other substances which have a fluorescent 
brightening action, 
(h) in spinning bath preparations, i.e. as additives to spinning baths 
which are used for improving the slip for the further processing of 
synthetic fibres, or from a special bath prior to stretching the fibre, 
(i) as scintillators for various purposes of a photographic nature, for 
example for electrophotographic reproduction or supersensitising, and 
(j) depending on the substitution, as laser dyes. 
If the brightening process is combined with textile treatment or finishing 
methods, the combined treatment can in many cases advantageously be 
carried out with the aid of appropriate stable preparations which contain 
the fluorescent brightener compounds in such a concentration that the 
desired white effect is achieved. 
In certain cases, the fluorescent brighteners are made fully effective by 
an after-treatment. This can be, for example, a chemical treatment (for 
example acid treatment), a heat treatment (for example heating) or a 
combined chemical/heat treatment. Thus, for example, the appropriate 
procedure to follow in fluorescent brightening a number of fibre 
substrates, for example polyester fibres, with the fluorescent brightening 
agents of the present invention, is to impregnate these fibres with 
aqueous dispersions (or, where appropriate, also solutions) of the 
fluorescent brightening agents at temperatures below 75.degree. C., for 
example at room temperature, and to subject them to a dry heat treatment 
at temperatures above 100.degree. C., it generally being advisable 
additionally to dry the fibrous material beforehand at a moderately 
elevated temperature, for example at not less than 60.degree. C. to about 
130.degree. C. The heat treatment in the dry state is then advantageously 
carried out at temperatures between 120.degree. C. and 225.degree. C., for 
example by heating in a drying chamber, by ironing within the specified 
temperature range or by treatment with dry, superheated steam. Drying and 
the dry heat treatment can also be carried out in immediate succession or 
combined in a single operation. 
The amount of the novel fluorescent brightening agents to be used according 
to the invention, based on the material to be subjected to fluorescent 
brightening, can vary within wide limits. A marked and lasting effect can 
be obtained even with very small amounts, in certain cases, for example, 
amounts of 0.0001 percent by weight. However, it is also possible to use 
amounts of up to about 0.8 percent by weight and, where necessary, of up 
to about 2 percent by weight. For most practical purposes, it is 
preferable to use amounts of between 0.0005 and 0.5 percent by weight. 
For various reasons, it is often advantageous not to employ the fluorescent 
brighteners by themselves, i.e. pure, but in admixture with a very wide 
variety of assistants and extenders, for example sodium formate, sodium 
acetate or lactate. 
The novel fluorescent brighteners of the formula (1) and subordinate 
formulae in which n is the number 1, have the particular advantage that 
they are resistant to chlorites. 
In the examples, unless otherwise indicated, parts are always by weight and 
percentages are always by weight. Unless indicated otherwise, melting 
points and boiling points are uncorrected.

EXAMPLE 1 
A mixture of 27.3 g of 2-benzimidazol-2'-yl-6-methoxy-benzofuran (c.f. 
British Pat. No. 1,313,332), 100 ml of chloroacetonitrile and 14.7 g of 
anhydrous ground potassium carbonate is stirred for 6 hours at reflux 
temperature. In the course of this, the starting material dissolves, after 
which the reaction product is precipitated. After being cooled to room 
temperature the mixture is filtered with suction and the residue is washed 
several times with isopropanol and water. This gives 19.3 g of the 
compound of the formula 
##STR23## 
which is recrystallised from perchloroethylene and xylene (light yellow 
crystals of melting point 188.degree.-91.degree. C.). 
The compounds of the formula 
##STR24## 
are obtained similarly. 
EXAMPLE 2 
The procedure described in Example 1 is repeated, using 60 ml of 
2-bromoproprionitrile instead of chloroacetonitrile and adding a further 
8.9 g of potassium carbonate in portions during the course of the 
reaction. The compound of the formula 
##STR25## 
is obtained. 
This compound is purified by being chromatographed over aluminium oxide of 
neutral activity 1, using ethylene chloride, followed by recrystallisation 
from isopropanol (melting point 72.degree. C.). 
EXAMPLE 3 
19.8 g of a 30% strength solution of sodium methylate are added dropwise, 
while stirring, to a hot solution of 27.3 g of 
2-benzimidazol-2'-yl-6-methoxy-benzofuran in 450 ml of methanol. The 
methanol is removed completely by distillation, finally in vacuo. 50 ml of 
ethyl bromoacetate are added to the solid residue, the suspension is 
stirred for 1 hour at 50.degree. C. and diluted with 250 ml of methylene 
chloride after cooling to room temperature, and insoluble material is 
filtered off. The resulting solution is evaporated in vacuo and the 
residue is taken up in 450 ml of hot ethylene chloride. Cooling to 
0.degree. C. produces a thick precipitate of the product. This is filtered 
off, washed with ethylene chloride and dried in vacuo at 70.degree. C. to 
give 33.5 g of the compound of the formula 
##STR26## 
which, after recrystallisation from isopropanol, is obtained in the form 
of nearly colourless crystals of melting point 178.degree.-180.degree. C. 
(decomposition). 
EXAMPLE 4 
11 ml of a 10N aqueous solution of potassium hydroxide are added, at 
70.degree. C. and while stirring, to a suspension of 27.3 g of 
2-benzimidazol-2'-yl-6-methoxy-benzofuran in 100 ml of ethanol, and the 
resulting solution is evaporated completely in vacuo. 50 ml of ethyl 
chloroacetate are added to the solid residue, the suspension is stirred 
for 1/2 hour at 130.degree. C. and, after cooling, diluted with 100 ml of 
methylene chloride, and insoluble material is filtered off. The solution 
is evaporated in vacuo and the residue is taken up in 100 ml of warm 
acetone. The product is precipitated slowly on cooling the solution to 
0.degree. C. It is filtered off, washed with acetone and dried in vacuo at 
room temperature to give 10.2 g of the compound of the formula 
##STR27## 
This compound can be recrystallised from acetone: melting point 
153.degree.-158.degree. C. (decomposition). 
EXAMPLE 5 
A mixture of 27.3 g of 2-benzimidazol-2'-yl-6-methoxy-benzofuran, 80 ml of 
methyl chloroacetate and 15.2 g of anhydrous, ground potassium carbonate 
is stirred for 4 hours at 90.degree. C., and insoluble material is 
filtered off while the mixture is still hot. The filtrate is evaporated 
completely in vacuo and the residue is taken up in 80 ml of warm methanol. 
After the solution has been cooled to 0.degree. C., 50 ml of water are 
added, while stirring, whereupon the reaction product is precipitated 
gradually. It is filtered off with suction, washed several times with a 
1:1 mixture of methanol and water and dried in vacuo over calcium 
chloride. Recrystallisation from carbon tetrachloride gives 23.0 g of the 
compound of the formula 
##STR28## 
Melting point 111.degree.-113.degree. C. (from isopropanol). 
8.4 g of this product are stirred in 20 ml of chloroacetonitrile for 2 
hours at 120.degree. C. and the solution is evaporated completely in vacuo 
on a rotary evaporator. The residue is taken up in 70 ml of chloroform and 
the product which has precipitated is filtered off with suction, washed 
with three times 20 ml of chloroform and dried in vacuo. This gives 7.7 g 
of the compound of the formula 
##STR29## 
of melting point 150.degree. C. (decomposition). The product can be 
recrystallised from ethanol. 
EXAMPLE 6 
A suspension of 4.2 g of 6-methoxy-coumarilyl chloride and 4.3 g of the 
compound of the formula 
##STR30## 
in 20 ml of pyridine is stirred for 1/2 hour at 100.degree. C. The 
reaction product is precipitated on cooling the solution to 5.degree. C. 
The product is filtered off with suction, washed several times with 
acetone and toluene and dried in vacuo at 100.degree. C. This gives 5.9 g 
of the compound of the formula 
##STR31## 
in the form of light yellow crystals of melting point 
215.degree.-216.degree. C. (decomposition). 
EXAMPLE 7 
39.6 g of 2-benzimidazol-2'-yl-6-methoxybenzofuran are stirred in 180 ml of 
acrylonitrile and 18.5 g of triethylamine for 44 hours at reflux 
temperature. The triethylamine and the excess acrylonitrile are filtered 
off, the residue is dissolved in toluene and the solution is filtered 
while hot and allowed to cool. The product which has precipitated is 
filtered off with suction, washed with toluene and dried in vacuo at 
100.degree. C. This gives 43.2 g of the compound of the formula 
##STR32## 
Melting point 131.degree.-133.degree. C. (after recrystallisation from 
toluene). 
6.4 g of this product in 20 ml of chloroacetonitrile are heated at reflux 
temperature for 'hours. 80 ml of methyl ethyl ketone are added to the 
solution and the mixture is allowed to cool. The product which as 
crystallised out is filtered off with suction, washed several times with 
methyl ethyl ketone and dried in vacuo at 100.degree. C. This gives 5.7 g 
of the compound of the formula 
##STR33## 
Melting point 195.degree.-201.degree. C. The compound can be 
recrystallised from isopropanol. 
EXAMPLE 8 
29.5 g of 2-benzimidazol-2'-yl-5-(p-chlorophenyl)-furan are dissolved by 
warming in 20 ml of methanol and 11 ml of 10N sodium hydroxide solution. 
The solution is evaporated completely in vacuo, 100 ml of 
chloroacetonitrile are added and the suspension is stirred for 4 hours at 
70.degree. C. After it has been cooled to room temperature, the suspension 
is diluted with 100 ml of methanol and 10 ml of water and is filtered, and 
the residue is washed several times with methanol and water. The residue 
is dried in vacuo at 100.degree. C. (28.0 g) and is recrystallised from 
n-butanol. This gives 20.9 g of the compound 
##STR34## 
in the form of pale yellow crystals of melting point 
233.degree.-226.degree. C. (from xylene). 
6.7 g of this product are stirred in 20 ml of ethyl bromoacetate for 2 
hours at 100.degree. C. After the starting material has dissolved, a 
voluminous precipitate of the end product is formed. The mixture is 
diluted with 50 ml of methyl ethyl ketone and is filtered with suction at 
approx. 40.degree. C., and the residue is washed with methyl ethyl ketone. 
Drying gives 7.3 g of the compound 
##STR35## 
which is obtained in the form of light yellow crystals of melting point 
170.degree. C. (not sharp), after recrystallisation from water 
EXAMPLE 9 
5.9 g of 2-benzimidazol-2'-yl-5-(p-chlorophenyl)-furan and 3.3 g of 
anhydrous, ground potassium carbonate are stirred in 30 ml of 
chloroacetonitrile for 18 hours at reflux temperature. The excess 
chloroacetonitrile is distilled off in vacuo, the residue is extracted by 
boiling with 80 ml, and then 20 ml, of water, and the aqueous phases are 
decanted off at 100.degree. C. The combined aqueous phases are clarified 
by filtration while hot, after adding active charcoal, and are 
concentrated somewhat, after which the product crystallises out on 
cooling. The product is filtered off with suction, washed with water and 
dried in vacuo at 100.degree. C. This gives 1.8 g of the compound of the 
formula 
##STR36## 
in the form of light yellow crystals which still contain 1/2 mol of water 
of crystallisation. Melting point 205.degree.-207.degree. C. (after 
recrystallisation from 3:7 alcohol/acetonitrile). 
The procedure used in this example is repeated, using a corresponding 
quantity of 2-benzimidazol-2'-yl-5-phenylfuran instead of the furan 
derivative mentioned. The compound of the formula 
##STR37## 
is obtained. 
The compound of the formula 
##STR38## 
is obtained analogously. 
EXAMPLE 10 
The procedure used in Example 3 is repeated, using as the starting material 
2-benzimidazol-2'-yl-5-(p-chlorophenyl)-furan instead of the 
2-benzimidazol-2'-yl-6-methoxy-benzofuran mentioned. The compound of the 
formula 
##STR39## 
is obtained. 
EXAMPLE 11 
7.0 g of 2-[1'-cyanoethyl-benzimidazol-2'-yl]-5-(p-chlorophenyl)-furan 
(c.f. U.S. Pat. No. 3,637,734) are stirred in about 30 ml of 
chloroacetonitrile for 8 hours at reflux temperature. The excess 
chloroacetonitrile is filtered off in vacuo, the residue is extracted by 
boiling with three times 40 ml of water and the aqueous phase is decanted 
off at 100.degree. C. in each case. After adding active charcoal, the 
combined aqueous solutions are clarified by filtration while hot, after 
which the product crystallises out on cooling. It is filtered off with 
suction, washed with water and dried in vacuo at 100.degree. C. This gives 
5.2 g of the compound of the formula 
##STR40## 
Melting point 255.degree. C. (after recrystallisation from n-propanol). 
EXAMPLE 12 
A polyacrylonitrile fabric (Orlon 75) is treated on a dyeing machine, at a 
liquor ratio of 1:20, with an aqueous liquor containing 0.1%, based on the 
weight of the goods, of a fluorescent brightener of the formula (100), 
(200), (300), (601), (701), (801), (900) or (1100), 1 g/l of an adduct of 
35 mols of ethylene oxide and 1 mol of stearyl alcohol, and 1.5 ml/l of 
85% strength formic acid. Application is carried out in accordance with 
the following temperature programme: 40.degree.-97.degree. C./30 minutes, 
97.degree. C./30 minutes and 97.degree.-40.degree. C./15 minutes. The 
polyacrylonitrile fabric is then rinsed for 30 seconds in running, 
softened water and is dried at 70.degree. C. in a drying cabinet. The 
fabric treated in this way has a high white effect. 
EXAMPLE 13 
A modified polyacrylonitrile fabric (Courtelle) is treated on a dyeing 
machine, at a liquor ratio of 1:20, with an aqueous liquor containing 
0.1%, based on the weight of the goods, of a fluorescent brightener of the 
formula (300), (601), (701), (900) or (1100), 1 g/l of oxalic acid, 0.25 
g/l of a polyphosphate as a complex-forming agent and 0.125 g/l of sodium 
metabisulfite. Application is carried out in accordance with the following 
temperature programme: 40.degree.-97.degree. C./30 minutes, 97.degree. 
C./30 minutes and 97.degree.-40.degree. C./15 minutes. The 
polyacrylonitrile fabric is then rinsed for 30 seconds in running, 
softened water and is dried at 70.degree. C. in a drying cabinet. The 
fabric treated in this way has a good white effect. 
EXAMPLE 14 
A freshly spun, stretched, never-dried polyacrylonitrile tow (corresponding 
to a dry weight of 3.0 g) is immersed, while still moist, for 4 seconds at 
45.degree. C. in 100 ml of an aqueous liquor which contains 0.005% of a 
brightener of the formula (300), (601), (900) or (1100) and which has been 
adjusted to pH 4 with concentrated oxalic acid solution. The never-dried 
tow is then rinsed for a short time with water and is dried at 90.degree. 
to 100.degree. C. A polyacrylonitrile fibre which has a good white effect 
is obtained in this way. The dyeing can also be carried out, for example, 
at pH 6 (adjusted by adding sodium acetate). Increasing the temperature of 
the dyeing liquor, for example to 40.degree. C., increases the rate of 
exhaustion. 
Higher white effects are achieved by increasing the concentration of 
fluorescent brightener, for example to 0.005%. 
EXAMPLE 15 
An aqueous solution is prepared containing 0.3%, based on the weight of the 
material to be whitened, of a fluorescent brightener of the formula (300), 
(801) or (900). This solution is warmed to 30.degree. C. A modified 
polyester fabric (.RTM.Dacron 64), prepared by co-condensation with 2 to 5 
mol % of isophthalic acid 5-sodium sulfonate, is then put into the 
solution, a liquor ratio of 1:25 being maintained. The temperature is 
raised to 100.degree. C. in the course of 10 minutes and the mixture is 
kept at this temperature for 20 minutes. It is then cooled to 50.degree. 
C. in the course of 5 minutes. The fabric is then rinsed in running cold 
water and is subsequently dried at 180.degree. C. with a flat-iron. It has 
a high white effect.