Process for the preparation of sulphoalkyl quaternary salts

Quaternary sulfoalkyl or sulfoalkenyl salts of tertiary amine bases are prepared by reacting the tertiary amine bases at elevated temperatures with a hydroxy alkane sulfonic acid or a hydroxyalkene sulphonic acid.

This invention relates to a process for the preparation of sulfoalkyl 
quaternary salts of tertiary amines, in particular of nitrogen-containing 
heterocyclic bases. 
These quaternary salts, which contain positively and negatively charged 
groups joined together by covalent bonds, are also known as betaines. They 
play an important part in many commercial processes, in which they are 
either used as such, for example in electroplating work, or serve as 
intermediate products for further reactions. When sulfoalkyl betaines are 
used as intermediate products, it is frequently advantageous for 
commercial reasons not to isolate them first but to carry out the further 
reaction immediately after their preparation, in a single operation. As 
intermediate products, sulphoalkylbetaines are important, for example, for 
the synthesis of polymethine dyes which are used as spectral sensitizers 
for light-sensitive materials, in particular for photographic silver 
halide emulsions. To this extent, the present invention also relates to 
the conversion of the heterocyclic bases to polymethine dyes by way of the 
sulfoalkyl quaternary salts. 
Processes for the preparation of sulfoalkyl quaternary salts of tertiary 
amines have been known for a long time. The tertiary bases are reacted 
with a sulfoalkylating agent, generally at elevated temperatures. 
Compounds which have been described as sulfoalkylating agents include the 
halogen alkane sulfonic acids such as 2-bromoethane sulphonic acid 
described in U.S. Pat. No. 2,503,776; sodium iodoethane sulfonate 
described in Belgian Pat. No. 669,308; sodium iodobutane sulfonate 
described in U.S. Pat. No. 2,912,329 and 3-chloro-2-hydroxypropane 
sulfonic acid described in German Auslegeschrift No. 1,177,482. 
Disadvantages of these sulfoalkylating agents are the high reaction 
temperatures required and the excess of tertiary base which is required 
when free sulfonic acids are used to take up the hydrogen halide formed in 
the reaction. Sultones are also known as sulfoalkylating agents, for 
example propane-, butane- and isopentane-sultone have been described in 
German Pat. No. 929,080; propanesultone in German Auslegeschrift No. 
1,447,579 and 2-chloropropane sultone in British Pat. No. 1,090,626. One 
disadvantage of sultones is that in some cases they have a considerable 
carcinogenic potential which makes them dangerous to handle [see H. 
Druckrey et al Naturwiss. 55 (1968) 449; Z. Krebsforschung 75 (1970) 69]. 
An object of the present invention is therefore to provide a process for 
the preparation of sulfoalkyl and sulfoalkenyl quaternary salts in which 
the disadvantages mentioned above would be reduced or substantially 
obviated. 
A process for the preparation of a sulfoalkyl or sulfoalkenyl-quaternary 
salt of a tertiary amine has now been found in which the tertiary amine is 
reacted with a hydroxyalkane- or hydroxyalkenesulphonic acid. The reaction 
is generally carried out at an elevated temperature, e.g. at a temperature 
of from 100.degree. C. to 250.degree. C., preferably from 140.degree. C. 
to 200.degree. C. 
The reaction generally proceeds quite smoothly within the last mentioned 
temperature range but temperatures outside this range may also be 
employed, depending to some extent on the nature of the solvent used, e.g. 
temperatures above 200.degree. C., provided a higher boiling solvent is 
used as carrier for the water released by the reaction. 
Suitable for use as tertiary amines are in principle any derivatives of 
ammonia (NH.sub.3) in which all three hydrogen atoms are substituted, e.g. 
by a carbon atom of an alkyl or aryl group or by a carbon atom or a hetero 
atom of a heterocyclic ring, in which case the nitrogen atom of the 
tertiary amine, in particular, may be included in the heterocyclic ring. 
Particularly suitable heterocyclic bases are those corresponding to the 
following general formula I 
##STR1## 
in which Z represents the members required to complete a heterocyclic 
group having at least one 5-membered or 6-membered heterocyclic ring; this 
hetero ring may contain condensed benzene, naphthalene or heterocyclic 
rings, which may in turn be substituted; the heterocyclic groups may be 
those known from the chemistry of cyanine dyes, e.g. the following: 
Pyrroline (e.g. 4,4-dimethyl-pyrroline); oxazoline (e.g. 
4,4-dimethyloxazoline); thiazoline (e.g. 5-methyl-thiazoline); 
selenazoline; indoline (e.g. 3,3-dimethylindoline, 
3,3-dimethyl-5-methoxyindoline and 3,3-dimethyl-5-diethylaminoindoline); 
benzimidazole (e.g. 1-ethyl-5-trifluoromethyl-benzimidazole, 
1-methyl-5-chlorobenzimidazole, 1-ethyl-5,6-dichlorobenzimidazole, 
1-ethyl-5-cyanobenzimidazole, 1-methyl-5-carbethoxybenzimidazole, 
1-ethyl-5-acetylbenzimidazole, 1-methyl-benzimidazole-5-sulfonic acid 
pyrrolidide, 1-ethylbenzimidazole-5-sulphonic acid dimethylamide, 
1-ethyl-5-phenylthiobenzimidazole, 1-methyl-5-methylthiobenzimidazole and 
1-methyl-5-chloro-6-methylthiobenzimidazole); oxazole (e.g. 
4-methyloxazole, 4,5-diphenyloxazole, 4-methyl-5-carbethoxyoxazole, 
benzoxazole, 5-chlorobenzoxazole, 5-phenylbenzoxazole, 
6-methoxybenzoxazole, 5-methoxybenzoxazole, 5-methyl-6-methoxybenzoxazole, 
5-bromobenzoxazole, 5-iodobenzoxazole, naphtho[2,1-d]oxazole, 
naphtho[1,2-d]oxazole, naphtho[2,3-d]oxazole, 
4,5,6,7-tetrahydrobenzoxazole and benzofuro[2,3-f]benzoxazole); thiazole 
(e.g. 4-methylthiazole, 4-phenylthiazole, 4-methyl-thiazole-5-acrylic acid 
ethyl ester, benzothiazole, 5-methylbenzothiazole, 6-methylbenzothiazole, 
5-chlorobenzothiazole, 5-methoxy-benzothiazole, 6-methoxy-benzothiazole, 
5,6-dimethyl-benzothiazole, 5,6-dimethoxy-benzothiazole, 
5-methyl-6-methoxybenzothiazole, 5-bromobenzothiazole, 
5-phenyl-benzothiazole, 6-methylthiobenzothiazole, 
6-dimethylaminobenzothiazole, 5-chloro 6-methoxy-benzothiazole, 
5,6-methylenedioxybenzothiazole, 6-.beta. -cyanoethoxy-benzothiazole, 
5-carbomethoxybenzothiazole, 5-nitro-benzothiazole, 
5-phenylthiobenzothiazole, 5-thienyl-benzothiazole, 
6-hydroxybenzothiazole, 4,5,6,7-tetrahydro-benzothiazole, 
4-oxo-4,5,6,7-tetrahydrobenzothiazole, naphtho[2,1-d]thiazole, 
naphtho[1,2-d]-thiazole, 4,5-dihydronaphtho[1,2-d]thiazole, 
5-methoxynaphtho[1,2-d]thiazole and 
5,7,8-trimethoxy-naphtho[1,2-d]thiazole); 
selenazole (e.g. benzoselenazole, 5-methylbenzoselenazole, 
5,6-dimethyl-benzoselenazole, 5-methoxybenzoselenazole, 
5-methyl-6-methoxybenzoselenazole, 5,6-dimethoxy-benzoselenazole, 
5,6-methylenedioxybenzoselenazole, 6-methyl-benzoselenazole and 
naphtho[1,2-d]selenazole); 1,3,4-oxadiazole (e.g. 
5-methyl-1,3,4-oxadiazole, 5-phenyl-1,3,4-oxadiazole); 1,3,4-thiadiazole 
(e.g. 5-methyl-1,3,4-thiadiazole, 2,5-bis-methylthio-1,3,4-thiadiazole, 
5-benzylthio-1,3,4-thiadiazole, 2-mercapto-5-methylthio-1,3,4-thiadiazole 
and 5-carbethoxymethylthio-1,3,4-thiadiazole); pyridine (e.g. 
2-methylpyridine and 4-methylpyridine); pyrimidine (e.g. 
2-methyl-4-methylthiopyrimidine); quinoline (e.g. 6-methylquinoline, 
8-chloroquinoline, 6-fluoroquinoline, 5,6-benzoquinoline and 
6,7-benzoquinoline) and imidazolo[4,5-b]quinoxaline; 
n=0 or 1, 
Y represents hydrogen, halogen, a saturated or unsaturated aliphatic group, 
an alkoxy group, an alkylthio group or a mercapto group. 
The saturated and unsaturated alkyl groups, alkoxy groups and alkylthio 
groups represented by Y may have, in particular, up to 6 carbon atoms and 
may be further substituted. Specific examples of saturated or unsaturated 
alkyl groups represented by Y are methyl, ethyl, alkyl, cyanoalkyl, 
haloalkyl, alkoxyalkyl and, in particular a methine chain having 1,3, or 5 
methine groups, at the end of which chain, in most cases attached through 
the 2-position, there is an N-alkylated heterocyclic base, of the type 
known in the chemistry of cyanine dyes. References may be found in F. M. 
Hamer "The Cyanine Dyes and Related Compounds", (1964), Interscience 
Publishers John Wiley and Sons. Compounds corresponding to formula I in 
which Y has the meaning defined above are referred to as "dequaternised 
cyanine dyes". When such dequaternised cyanine dyes are reacted by the 
process according to the invention, the products directly obtained from 
the process are suitable for use as spectral sensitizers without any 
further reaction. 
Specific examples of an alkoxy group represented by Y are carboxyalkoxy 
groups such as carboxy methoxy. Specific examples of an alkylthio group 
represented by Y are methylthio and carboxymethylthio. 
Suitable hydroxyalkane and hydroxyalkene sulfonic acids are in particular 
those corresponding to the general formula II 
EQU HO--CH.sub.2 --X--SO.sub.3 H (II) 
in which X represents a substituted or unsubstituted saturated or 
unsaturated divalent aliphatic hydrocarbon group, preferably one having up 
to 7 carbon atoms. This hydrocarbon group may be substituted, for example 
by hydroxyl, halogen, alkoxy or cyano. 
The following groups are examples of X: 
--(CH.sub.2).sub.m -- in which m represents an integer of from 1 to 7, 
preferably from 1 to 3, 
##STR2## 
Instead of the free tertiary amine bases, there may also be used their 
salts with inorganic or organic acids, e.g. the hydrohalides, hydrogen 
sulfates, p-toluenesulphonates, perfluorobutyrates and acetates. 
Metal salts of the sulfonic acids, e.g. their alkaline earth metal salts, 
may also be used instead of the free sulfonic acids. These salts are 
preferably reacted with the salts of the tertiary bases. 
Hydroxyalkane and hydroxyalkene sulphonates of tertiary amines are also 
suitable for the reaction according to the invention. 
The reactions are generally carried out without solvents although a 
suitable solvent may be used. Any solvents which are inert in the reaction 
according to the invention and have a high dissolving power for the 
reactants are suitable, e.g. phenol or m-cresol, or solvents which form an 
azeotropic mixture with water, e.g. benzene, toluene, m-xylene, n- or 
i-butanol, isoamylalcohol, chlorobenzene and anisole. 
The reactions according to the invention are accompanied by the elimination 
of water. This water of reaction is preferably removed from the reaction 
vessel, for example, by 
(1) operating under a vacuum, 
(2) introducing an anhydrous inert gas, e.g.: nitrogen, 
(3) azeotropic distillation with one of the solvents mentioned above or 
(4) the presence of a dehydrating agent either in the reaction vessel (e.g. 
anhydride of an organic acid) or in a receiver attached to the reaction 
vessel (e.g. P.sub.4 O.sub.10, concentrated sulphuric acid, sodium 
hydroxide or other dehydrating agent). 
Sulfobetaines of tertiary amines prepared by the process according to the 
invention include in particular those of the following formula III 
##STR3## 
in which n, X, Y and Z have the meanings already specified. These 
compounds are used for various purposes. For example, they are suitable 
for use as conductive salts for electroplating. Compounds of the above 
formula III may also be the end products of a cyanine dye synthesis if Y 
has the appropriate meaning, i.e. If, as already mentioned above, it 
represents a methine chain containing 1, 3 or 5 methine groups with a 
N-alkylated heterocyclic base attached to the end of the chain. Compounds 
of this type may be used directly for the spectral sensitisation of 
light-sensitive silver halide emulsions. Generally, the compounds prepared 
by the process of the invention are also important as intermediate 
products for the synthesis of polymethine dyes. Thus, for example, the 
sulfoalkenyl or sulphoalkenyl quaternary salts of heterocyclic bases 
prepared by the process according to the invention are preferably not 
isolated but reacted to form polymethine dyes in known manner after the 
quaternisation reaction without any further purification. 
The hydroxyalkane- or hydroxyalkene-sulfonic acids used according to the 
invention may be prepared by known methods, e.g. by the reaction of a 
halogen substituted alcohol with an alkali metal sulphite or by chemical 
addition of bisulphite or sulphur dioxide to a suitable unsaturated 
alcohol or to an unsaturated aldehyde, followed by reduction. In this way, 
3-hydroxy-1-propane sulfonic acid is prepared from allyl alcohol by the 
chemical addition of sodium bisulphite [J. H. Helberger, Liebigs Ann. 
Chem. 588, 71 (1954)]. 3-Hydroxy-2-methyl-1-propane sulfonic acid is 
prepared by the chemical addition of bisulphite to methacrolein followed 
by reduction with H.sub.2 /Raney nickel (C. W. Smith et al., J. Amer. 
Chem. Soc. 75, 748 (1953)). 4-Hydroxy-2-butanesulfonic acid may be 
prepared in analogous manner from crotonaldehyde [G. Haubner, Mh. Chemie 
12, 541 (1891)]. 4-Hydroxy-1-butane sulfonic acid may be obtained by the 
reaction of 4-chloro-n-butanol with sulphite (J. H. Helberger, H. 
Lantermann, Liebigs Ann. Chem. 586, 161 (1954)). 3-Hydroxy-1-propene 
sulfonic acid may be obtained as a mixture of the cis- and trans- isomers 
by the chemical addition of bisulfite to propargyl alcohol (German 
Auslegeschrift No. 1,146,870).

The process according to the invention and its variations are described in 
more detail in the following Examples. 
EXAMPLE 1 
Anhydro-2,5,6-trimethyl-3-(3'-sulfobutyl)-benzothiazolium hydroxide. 
(a) 3.5 g of 2,5,6-trimethyl-benzothiazole and 3.1 g of 4-hydroxy-2-butane 
sulfonic acid were heated to 175.degree. C. in an oil bath for 4 hours. 
After cooling, the reaction product was recrystallised from 
methanol/isopropanol. 
Yield: 2.2 g 
Mp: 288.degree.-289.degree. C. 
IR Bands: 780, 895, 1040, 1200, 1230, 1450, 1470, 3000, and 3400 cm.sup.-1. 
(b) 3.5 g of 2,5,6-trimethyl-benzothiazole, 3.1 g of 4-hydroxy-2-butane 
sulfonic acid and 1 g of acetic anhydride were heated to 175.degree. C. in 
an oil bath for 5 hours. After cooling, the reaction product was 
recrystallised from methanol. 
Yield: 2.4 g 
Mp: 288.degree. C. 
IR Spectrum identical to that of (a). 
EXAMPLE 2 
Anhydro-2,5,6-trimethyl-3-(3'-sulfopropyl)-benzothiazolium hydroxide. 
(a) 5.3 g of 2,5,6-trimethyl-benzothiazole and 4.2 g of 3-hydroxy-1-propane 
sulfonic acid were heated to 175.degree. C. in an oil bath for 5 hours. 
After the first 3 hours, 15 ml of n-butanol were added dropwise and then 
distilled off as azeotropic mixture with the water formed in the reaction. 
The quaternary salt produced may be recrystallised from ethanol. 
Yield: 4.9 g 
Mp: 280.degree. C. 
IR Bands: 785, 880, 1040, 1200, 1240, 1345, 1395, 1450, 2900-3000, 3410 
cm.sup.-1. 
Similar results were obtained when toluene or chlorobenzene was used 
instead of n-butanol. 
(b) 3.5 g of 2,5,6-trimethyl-benzothiazole, 4.2 g of 3-hydroxy-1-propane 
sulfonic acid and 1 g of acetic anhydride were heated to 175.degree. C. in 
an oil bath for 5 hours. 
The reaction product was worked up with methanol/isopropanol. 
Yield: 5.7 g 
Propionic acid anhydride may be used instead of acetic anhydride. 
EXAMPLE 3 
Anhydro-2,5-dimethyl-3-(3'-sulfopropyl)-benzothiazolium hydroxide. 
(a) Obtained from 2/100 mol of 2,5-dimethyl-benzothiazole and 2/100 mol of 
3-hydroxy-1-propane sulfonic acid by the method described in example 1b). 
Yield: 3.7 g, Mp: 253.degree. C. 
(b) The same as (a) but using 2/100 mol of 2,5-dimethyl-benzothiazole 
hydrobromide without acetic anhydride or 1/100 mol of 
2,5-dimethyl-benzothiazole and 1/100 mol of 2,5-dimethyl-benzothiazole 
hydrobromide instead of 2/100 mol of the free base. 
(c) From 2/100 mol of 2,5-dimethyl-benzothiazole hydrobromide and 2/100 mol 
of a 1:1 mixture of sodium and potassium salt of 3-hydroxy-1-propane 
sulfonate by heating to 180.degree. C. for 1.5 hours and stirring after 
the mixture has melted. 
The preparations obtained according to (a) to (c) were found to have 
IR-spectra identical to that of a comparison sample prepared from 
2,5-dimethyl-benzothiazole and propane sultone. 
IR bands: 730, 735, 850, 1040, 1160, 1200, 1225, 1455, 2900-3000, 3410, 
3490 cm.sup.-1. 
EXAMPLE 4 
Anhydro-2-methyl-3-(3'-sulfopropyl)-benzothiazolium hydroxide. 
14.9 g of 2-methyl-benzothiazole and 16 g of 3-hydroxy-1-propane sulfonic 
acid in 100 ml of anisole were heated to 210.degree. C. (bath temperature) 
for 5 hours and the reaction mixture was slowly distilled at the same 
time. The residue was dissolved in alcohol and the solution was clarified 
with active charcoal and crystallized by the addition of isopropanol. 
Yield: 16 g 
Mp: 277.degree.-278.degree. C. 
IR bands: 790, 1040, 1150, 1170, 1185, 1215, 1240, 1430, 1460, 2850-3100, 
3400, 3530 cm.sup.-1. 
EXAMPLE 5 
Anhydro-2-methyl-3-(3'-sulfopropyl)-naphtho[1,2-d]-thiazolium hydroxide. 
19 g of 3-hydroxy-1-propane sulfonic acid were dissolved in 24 ml of acetic 
anhydride and left to stand for 20 minutes before 20 g of 
2-methyl-naphtho[1,2-d]thiazole were added. After 12 hours heating to 
175.degree. C., the reaction product was worked up with methanol. 
Yield: 12 g 
Mp: 275.degree. C. 
IR bands: 735, 760, 780, 850, 880, 1045, 1165, 1210, 1240, 1310, 1520, 
2900-3050, 3160, 3420, 3490 cm.sup.-1. 
EXAMPLE 6 
Anhydro-2-methyl-5-methoxy-3-(3'-sulfopropyl)-benzoxazolium hydroxide. 
8.2 g of 2-methyl-5-methoxybenzoxazole and 8 g of 3-hydroxy-1-propane 
sulfonic acid were heated to 180.degree. C. for 6 hours while a mixture of 
5 ml of acetic anhydride and 50 ml of anisole was slowly added dropwise 
and the reaction mixture is distilled at the same time. The residue was 
worked up with acetone and alcohol. 
Yield: 6.4 g 
Mp: 264.degree.-268.degree. C. 
IR bands: 790, 830, 960, 1010, 1040, 1200, 1235, 1310, 1405, 1450, 1480, 
1500, 1590, 1615, 2900-3050, 3400 cm.sup.-1. 
EXAMPLE 7 
Anhydro-2-methyl-5-phenyl-3-(3'-sulfopropyl)-benzoxazolium hydroxide. 
Prepared from: 
10.5 g of 2-methyl-5-phenyl-benzoxazole and 
8 g of 3-hydroxy-1-propane sulfonic acid by the method described in Example 
6. 
Yield: 12.4 g 
Mp: 282.degree. C. 
IR bands: 705, 780, 1040, 1200, 1410, 1475, 1600, 2900-3050, 3300-3400, 
3600 cm.sup.-1. 
EXAMPLE 8 
Anhydro-2-methyl-3-(3'-sulfopropyl)-naphtho[1,2-d]-oxazolium hydroxide. 
10.5 g of 2-methylnaphtho[1,2-d]oxazole. 
8 g of 3-hydroxy-1-propane sulfonic acid in 5 ml of acetic anhydride and 50 
ml of anisole were heated to 180.degree. C. for 6 hours under conditions 
of distillation while a dry stream of nitrogen was passed through the 
reaction mixture. 
Yield: 6.7 g 
Mp: 271.degree.-272.degree. C. 
IR Bands: 730, 780, 825, 1040, 1175, 1200, 1375, 1410, 1480, 1540, 1575, 
2900-3100, .about.3400 cm.sup.-1. 
EXAMPLE 9 
Anhydro-2-methyl-3-(3'-sulfopropyl)-6-methoxybenzoxazolium hydroxide. 
Prepared from 2-methyl-6-methoxy-benzoxazole by a method similar to that of 
Example 6. Mp: 277.degree. C. 
IR bands: 765, 780, 795, 820, 850, 1015, 1040, 1110, 1200, 1350, 1445, 
1505, 1595, 3000 cm.sup.-1. 
EXAMPLE 10 
Anhydro-2-methyl-3-(3'-sulfopropyl)-benzoxazolium hydroxide. 
Prepared from 7 ml of 2-methyl-benzoxazole and 8 g of 3-hydroxy-1-propane 
sulfonic acid by a method similar to that of Example 6. The reaction 
product was worked up with isopropanol and acetone. 
Yield: 5.2 g 
Mp: 138.degree.-142.degree. C. 
IR Bands: 785, 920, 1035, 1175, 1190, 1220, 1240, 1465, 1600, 2900-3100, 
3400, 3530 cm.sup.-1. 
Similar results were obtained when 4-chlorotoluene was used as solvent 
instead of anisole. 
EXAMPLE 11 
Anhydro-2-methyl-3-(3'-sulfopropyl)-benzoselenazolium hydroxide. 
2 g of 2-methyl-benzoselenazole, 1.4 g of 3-hydroxy-1-propane sulfonic acid 
and 0.5 ml of acetic anhydride were heated to 175.degree. C. in an oil 
bath for 4 hours. The reaction product was worked up with 
methanol/ethanol. 
Yield: 1.6 g 
Mp: 267.degree.-268.degree. C. (after recrystallization from ethanol, Mp: 
274.degree. C.). 
Slightly lower yields are obtained in the absence of acetic anhydride. 
EXAMPLE 12 
Anhydro-2,5-dimethyl-6-methoxy-3-(3'-sulfopropyl)benzoselenazolium 
hydroxide. 
A mixture of 4.8 g of 3-hydroxy-1-propane sulfonic acid, 1.5 ml of acetic 
anhydride and 7.2 g of 2,5-dimethyl-6-methoxybenzoselenazole were heated 
to 175.degree. C. for 4 hours while a dry stream of nitrogen was passed 
through. The reaction product was crystallized from alcohol and then from 
methanol. 
Yield: 5.3 g 
Decomposition at 310.degree. C. 
IR bands: 770, 785, 810, 880, 910, 1040, 1200, 1270, 1415, 1440, 1490, 
1525, 1580, 1610, 2910, 3010, 3400 cm.sup.-1. 
EXAMPLE 13 
Anhydro-2-methyl-5-methoxy-3-(3'-sulfopropyl)-benzoselenazolium hydroxide. 
Prepared from 2-methyl-5-methoxy-benzoselenazole and 3-hydroxy-1-propane 
sulfonic acid by a method similar to that of Example 12. 
Mp: 300.degree. C. 
IR bands: 800, 825, 840, 845, 1040, 1140, 1200, 1240, 1350, 1450, 1470, 
1605, 2900-3070, 3400 cm.sup.-1. 
EXAMPLE 14 
Anhydro-1,2-dimethyl-5,6-dichloro-3-(3'-sulfopropyl)-benzimidazolium 
hydroxide. 
Prepared from 4.3 g of 1,2-dimethyl-5,6-dichlorobenzimidazole and 2.8 g of 
3-hydroxy-1-propane sulfonic acid by 4 hours heating to 175.degree. C. and 
crystallization with isopropanol. 
Yield: 4.5 g 
Mp: 352.degree.-355.degree. C. 
IR bands: 720, 900, 1030, 1040, 1115, 1165, 1185, 1205, 1420, 1480, 1540, 
3010, 3400 cm.sup.-1. 
EXAMPLE 15 
Anhydro-1-ethyl-2-methyl-5,6-dichloro-3-(3'-sulfopropyl)-benzimidazolium 
hydroxide. 
Prepared from 1-ethyl-2-methyl-5,6-dichlorobenzimidazole by a method 
similar to that of Example 14. 
Yield: 43% 
Mp: 315.degree.-318.degree. C. 
IR bands: 1045, 1110, 1200, 1415, 1470, 1525, 2990, 3400 cm.sup.-1. 
EXAMPLE 16 
Anhydro-1,2-dimethyl-5-pyrrolidino-sulfonyl-3-(3'-sulphopropyl)-benzimidazo 
lium hydroxide. 
Prepared from 5.6 g of 1,2-dimethyl-5-pyrrolidino-sulfonyl-benzimidazole by 
3 hours heating to 185.degree. C. by a method similar to that of Example 
14. 
Yield: 6.7 g 
Mp: 332.degree. C. (from water) 
IR bands: 660, 1040, 1160, 1205, 1220, 1335, 1370, 1450, 1485, 3020, 3380 
cm.sup.-1. 
EXAMPLE 17 
Anhydro-1-(3'-sulfopropyl)-quinolinium hydroxide. Prepared by reacting 
quinoline and 3-hydroxy-1-propane sulfonic acid for 8 hours by a method 
similar to that of Example 14. Mp: 290.degree.-291.degree. C. 
IR bands: 790, 830, 1050, 1170- 1210, 1240, 1270, 1380, 1535, 1590, 1630, 
2960-3070, 3420 cm.sup.-1. 
EXAMPLE 18 
Anhydro-2-(3'-sulfopropyl)-isoquinolinium hydroxide. Similarly to Example 
17 from isoquinoline, Mp: 314.degree.-315.degree. C. 
IR bands: 730, 760, 795, 840, 1040, 1200, 1290, 1400, 1640, 3010, 3060, 
3400-3500 cm.sup.-1. 
EXAMPLE 19 
Anhydro-1-(3'-sulfopropyl)-2-methyl-quinolinium hydroxide. 
Similarly to Example 17 from quinaldine by 10 hours heating to 200.degree. 
C. 
Mp: 284.degree. C. 
IR bands: 730, 785, 840, 1040, 1155, 1200, 1370, 1525, 1600, 1620, 3070, 
.about.3400 cm.sup.-1. 
EXAMPLE 20 
Anhydro-1-(3'-sulfopropyl)-pyridinium hydroxide. Prepared similarly to 
Example 14 from 2 g of pyridine and 3 g of 3-hydroxy-1-propane sulfonic 
acid by heating to 175.degree. C. for 6 hours and crystallizing from 
methanol. 
Yield: 3.1 g 
Mp: 278.degree. C. 
IR bands: 695, 775, 790, 1040, 1145, 1170, 1200, 1220, 1240, 1470, 1490, 
1505, 1630, 2940, 3010-3100, 3400 cm.sup.-1. 
EXAMPLE 21 
Anhydro-2-methyl-3-(3'-sulfobutyl)-benzothiazolium hydroxide. 
Similarly to Example 14 from 3 g of 2-methyl-benzothiazole and 3.4 g of 
4-hydroxy-2-butane sulfonic acid by heating to 175.degree. C. for 4 hours. 
Yield: 2.2 g 
Mp: 277.degree.-278.degree. C. 
IR bands: 770, 790, 1030, 1170, 1200, 1340, 1380, 1440, 1460, 1475, 1515, 
1575, 1640, 2910-3070, 3430, 3480 cm.sup.-1. 
EXAMPLE 22 
Anhydro-2,5-dimethyl-3-(3'-sulfobutyl)-benzoselenazolium hydroxide. 
Similarly to Example 21 from 0.03 mol of 2,5-dimethylbenzoselenazole in 1 
hour, working up with isopropanol/acetone. 
Yield: 2.2 g 
Mp: 285.degree. C. (methanol). 
IR bands: 790, 830, 1040, 1190, 1280, 1440, 1460, 1650, .about.2930, 
.about.3450 cm.sup.-1. 
EXAMPLE 23 
Anhydro-2-methyl-3-(3'-sulfobutyl)-benzoselenazolium hydroxide. 
Similarly to Example 22 from 2-methyl-benzoselenazole and 
4-hydroxy-2-butane sulfonic acid by heating for 80 minutes at 150.degree. 
C. and 30 minutes at 175.degree. C. and working up the reaction melt with 
isopropanol and acetone. 
Mp: 290.degree. C. (methanol) 
IR bands: 780, 1035, 1175, 1205, 1440, 2940, 3060, 3400 cm.sup.-1. 
EXAMPLE 24 
Anhydro-2,5-dimethyl-3-(3'-sulfobutyl)-6-methoxybenzoselenazolium 
hydroxide. 
Similarly to Example 21 from 0.01 mol of 
2,5-dimethyl-6-methoxy-benzoselenazole by heating to 175.degree. C. for 1 
hour. Crystallized from isopropanol/methanol. 
Yield: 0.9 g 
Mp: 295.degree. C. 
IR bands: 780, 1035, 1185, 1200, 1260, 1440, 1470, 1490, 1520, 1605, 
2850-3100, 3400 cm.sup.-1. 
EXAMPLE 25 
Anhydro-2,5-dimethyl-3-(3'-sulfo-2'-propen-1'-yl)-benzothiazolium 
hydroxide. 
Similarly to Example (2b) from 2,5-dimethyl-benzothiazole and 
3-hydroxy-1-propene sulfonic acid, Mp: 280.degree.-282.degree. C. 
EXAMPLE 26 
Anhydro-2,6-dimethyl-3-(3'-sulfo-2'-propen-1'-yl)-benzothiazolium 
hydroxide. 
Similarly to Example 25 from 2,6-dimethyl-benzothiazole, 
Mp: 223.degree.-225.degree. C. 
EXAMPLE 27 
Anhydro-2,5-dimethyl-3-(3'-sulfo-2'-propen-1-yl)-benzoselenazolium 
hydroxide. 
Similarly to Example (2b) from 2,5-dimethyl-benzoselenazole and 
3-hydroxy-1-propene sulfonic acid, decomposition at 286.degree. C. 
EXAMPLE 28 
Anhydro-2,5-dimethyl-3-(3'-sulfo-2'-chloropropyl)-benzoselenazolium 
hydroxide. 
Similarly to Example (2b) from 2,5-dimethyl-benzoselenazole and 
3-hydroxy-2-chloro-1-propane sulfonic acid, decomposition at 
245.degree.-246.degree. C. 
EXAMPLE 29 
Anhydro-3-ethyl-3'-(3-sulfobutyl)-9-methyl-thiacarbocyanine hydroxide. 
14.9 g of 2-methyl-benzothiazole and 17.2 g of 4-hydroxy-2-butane sulfonic 
acid in 50 ml of anisole were heated to 200.degree. C. (bath temperature) 
for 3 hours. A mixture of water and anisole distilled off. The residue 
freed from anisole was heated gently with 28.9 g of 
2-(2-methylthio-1-propenyl)-3-ethyl-benzothiazolium methyl sulfate in 120 
ml of ethanol. After the addition of 24 ml of triethylamine at 40.degree. 
C., leaving to stand at room temperature for 3 hours and cooling with ice 
for 2 hours, the resulting dye was suction filtered, washed with methanol 
and recrystallized from a 1:3 mixture of chloroform and methanol. 
Yield: 25.5 g, Absorption maximum 544 nm (log .epsilon.=5.07). 
EXAMPLE 30 
Sodium salt of 
anhydro-5,5'-diphenyl-3,3'-bis-(3-sulfobutyl)-9-ethyl-oxacarbocyanine 
hydroxide. 
12 g of 2-methyl-5-phenyl-benzoxazole and 10.2 g of 4-hydroxy-2-butane 
sulfonic acid were heated to 200.degree. C. for 20 minutes and then for a 
further 20 minutes after the addition of 3 ml of acetic anhydride. The 
reaction product was taken up in 15 ml of m-cresol and converted into the 
dye by reaction with 15 ml of orthopropionic acid triethyl ester in the 
presence of 15 ml of triethylamine (40 minutes steam bath). After the 
m-cresol had been washed out with ethyl acetate, the dye was converted 
into its sodium salt with aqueous sodium chloride solution (30 minutes 
steam bath) and recrystallized from methanol/chloroform. 
Yield: 2.4 g, absorption maximum 503 nm (log .epsilon.=5.18). 
EXAMPLE 31 
Sodium salt of 
3-ethyl-5-[3-(3-sulfobutyl)-5-methylthio-1,3,4-thiadiazolin-2-ylidene]-rho 
danine. 
8.9 g of 2,5-bis-methylthio-1,3,4-thiadiazole and 8.6 g of 
4-hydroxy-2-butane sulphonic acid in 35 ml of anisole were heated to 
200.degree. C. for 1 hour. A mixture of water and anisole distilled off. 
The syrupy residue was washed with acetone and, after the addition of 3.5 
g of N-ethyl rhodanine, it was dissolved in 25 ml of ethanol. After the 
addition of 5 ml of triethylamine at 40.degree. C., the reaction mixture 
was left to stand for a further 2.5 hours and the resulting dye solution 
was then poured into 250 ml of water. After filtration, the dye was 
isolated by precipitation with saturated sodium chloride solution and 
suction filtration. 
Yield: 1.9 g, absorption maximum 421 nm (log .epsilon.=4.63). 
EXAMPLE 32 
Anhydro-3-(3'-sulfopropyl)-4,5-dimethyl-thiazolium hydroxide. 
Similarly to Example 14 from 6 g of 4,5-dimethyl thiazole and 8 g of 
3-hydroxy-1-propane sulfonic acid, by 5 hours heating at 175.degree. C. 
The product was worked up with acetone. 
Yield: 3.4 g, Mp: 174.degree.-175.degree. C. (methanol/isopropanol). 
IR bands: 750, 800, 870, 1035, 1200, 1450, 1590, 2990, 3400 cm.sup.-1. 
EXAMPLE 33 
Anhydro-3-methyl-3'-(3-sulfopropyl)-thia-2'-carbocyanine hydroxide. 
2.9 g of quinaldine, 3 g of 3-hydroxy-1-propane sulfonic acid and 2 ml of 
acetic anhydride were heated to 200.degree. C. (bath temperature) for 10 
hours. The residue was taken up with 40 ml of methanol and was then boiled 
on a steam bath for 5 minutes after the addition of 8 g of 
2-(2-acetanilido-vinyl)-3-methyl-benzothiazolium perchlorate and 3 ml of 
triethylamine. The resulting dye was boiled with water and recrystallized 
from chloroform/methanol. 
Yield: 3.4 g, 
Mp: 288.degree. C., absorption maximum 586 nm (log .epsilon.=5.08). 
EXAMPLE 34 
Potassium salt of 
anhydro-5,5',9-trimethyl-3,3'-bis(3-sulfopropyl)-thiacarbocyanine 
hydroxide. 
7.4 g of 2,5-dimethyl-benzothiazole hydrobromide and 6.1 g of potassium 
3-hydroxy-propane sulfonate were heated to 180.degree. C. for 1.5 hours. 
The reaction mixture was then dissolved in m-cresol and converted into the 
dye by reaction with triethyl ortho-acetate and triethylamine at 
60.degree. C. The dye was converted into its potassium salt with potassium 
acetate and recrystallized from methanol. 
Yield: 4.5 g, Mp: 298.degree.-302.degree. C., absorption maximum 548 nm 
(log .epsilon.=5.08). 
EXAMPLE 35 
Anhydro-3-ethyl-9-methyl-3'-(2-sulfoethyl)-thiacarbocyanine hydroxide. 
2.3 g of 2-methyl-benzothiazole hydrobromide and 1.5 g of sodium 2-hydroxy 
ethane sulfonate were heated to 220.degree. C. for 1 hour. The reaction 
mixture was taken up with methanol and to it were added 3.8 g of 
3-ethyl-2-(2-methylthio-1-propenyl)-benzothiazolium methyl sulfate. The 
dye crystallized after the addition of 2 ml of triethylamine and 5 minutes 
heating on the steam bath. 
Mp: 295.degree.-296.degree. C., absorption maximum: 541 nm. 
EXAMPLE 36 
Sodium salt of 
1,3-dimethyl-2-thio-5-[2-(6-methoxy-3-sulfopropyl-benzoxazolin-2-ylidene)- 
ethylidene]-hydantoin 1.4 g of 3-hydroxy propane sulfonic acid were mixed 
with 0.5 ml of acetic anhydride and, after the addition of 1.6 g of 
6-methoxy-2-methyl-benzoxazole, the mixture was heated to 180.degree. C. 
for 4 hours. After cooling to 70.degree. C., 3 g of diphenyl formamidine 
were added and the reaction mixture was heated to 130.degree. C. for 60 
minutes. After cooling to 80.degree. C., the reaction mixture was washed 
with ethyl acetate and the insoluble reaction product was taken up with 15 
ml of ethanol. After the addition of 1.4 g of 
1,3-dimethyl-2-thiohydantoin, 3 ml of triethylamine and 0.5 ml of acetic 
anhydride, the reaction mixture was stirred on a steam bath for 5 minutes 
and then left to stand at room temperature for 1 hour. The dye was 
precipitated with methanolic NaClO.sub.4 solution. 
Yield: 0.5 g, 
Mp: 328.degree.-332.degree. C., absorption maximum: 492 nm. 
EXAMPLE 37 
Potassium 
5-methyl-2-acetylmethylene-3-(3-sulfonato-2-propen-1-yl)-benzothiazoline. 
52 g of 2,5-dimethyl-benzothiazole hydrobromide and 48 g of potassium 
3-hydroxy-1-propensulphonate were heated to 140.degree. C. for 1 hour. 90 
ml of acetic anhydride and 32 ml of triethylamine were added to the 
resulting melt of the quaternary salt and the mixture was stirred at 
100.degree. C. for 1 hour. The acetic acid formed in the reaction was then 
distilled off and the residue was taken up with water. Hydrochloric acid 
was added, whereupon the intermediate product crystallized. 
Yield: 27 g, 
Mp: 245.degree.-248.degree. C. 
The intermediate product can be converted in known manner by stepwise 
reaction e.g. with (1) P.sub.2 S.sub.5, (2) dimethyl sulfate and (3a) a 
heterocyclic methyl quaternary salt into a symmetric or asymmetric 
carbocyanine or (3b) a heterocyclic ketomethylene compound into a 
dimethine merocyanine. 
EXAMPLE 38 
Anhyro-5-phenyl-3-(3-sulphopropyl)-3'-methyl-oxathiacarbocyanine hydroxide. 
1/100 ml of 5-phenyl-2-methyl-benzoxazole and 1/100 mol of 3-hydroxy 
propane sulfonic acid were heated to 175.degree. C. for 5 hours with the 
addition of 1/200 mol of acetic anhydride. 1/100 mol of 
2-.beta.-phenylimino-ethylidene-3-methyl-benzothiazoline, 10 ml of 
ethanol, 3 ml of triethylamine and 1 ml of acetic anhydride were added to 
the resulting melt when cold. The formation of dye was completed by 
heating the reaction mixture on a steam bath. Absorption maximum: 524 nm. 
EXAMPLE 39 
Anhydro-3-(3-sulfobutyl)-5'-chloro-3'-ethyl-oxathiacarbocyanine hydroxide. 
Similarly to Example 38 from 2-methyl-benzoxazole, 4-hydroxy-2-butane 
sulfonic acid and 
2-.beta.-phenyl-imino-ethylidene-3-ethyl-5-chlorobenzothiazoline. 
Absorption maximum: 523 nm. 
EXAMPLE 40 
Anhydro-5-methyl-3-(4-sulfobutyl)-5'-phenyl-3'-ethylthiaoxacarbocyanine 
hydroxide. 
1/100 mol of 2,5-dimethyl-benzothiazole hydrobromide were reacted by 
heating for 5 hours with 1/100 mol of 4-hydroxy-1-butane sulfonic acid. 
The reaction mixture was taken up with 15 ml of ethanol and after the 
addition of 1/100 mol of 2-acetanilido 
vinyl-3-ethyl-5-phenyl-benzoxazoliumiodide and 3 ml of triethylamine the 
dye was formed by boiling of the reaction mixture for 15 minutes. 
Absorption maximum: 526 nm. 
EXAMPLE 41 
Anhydro-5,5',6-trimethyl-3-(3-sulfopropyl)-3',9-diethylthiacarbocyanine 
hydroxide. 
2.6 g of 2,5,6-trimethyl-benzothiazole hydrobromide and 1.9 g of 
K-3-hydroxy-1-propane sulfonate were heated to 175.degree. C. for 3 hours 
while a stream of anhydrous nitrogen was passed through. When the reaction 
product had cooled, it was taken up with methanol, filtered from potassium 
bromide and then heated on a steam bath for 25 minutes after the addition 
of a methanolic solution of 3.4 g of 
3-ethyl-2-(2-methoxy-1-butenyl)-5-methyl-benzothiazolium methyl sulfate 
and 2.9 ml of triethylamine. The dye which crystallized was recrystallized 
from methanol/chloroform. 
Yield: 2.5 g, Mp: 295.degree.-296.degree. C., absorption maximum: 557 nm 
(log .epsilon.=5.08). 
EXAMPLE 42 
Anhydro-2-(2-anilinovinyl)-3-(3-sulfopropyl)-5-chlorobenzoxazolium 
hydroxide. 
8.5 g of 2-methyl-5-chlorobenzoxazole and 8 g of 3-hydroxy-1-propane 
sulfonic acid were heated to 180.degree. C. A mixture of 5 ml of acetic 
anhydride and 50 ml of anisole was then added dropwise over a period of 3 
hours while a stream of anhydrous nitrogen was passed through and the 
reaction mixture was distilled at the same time. Heating was then 
continued for 1 more hour at 180.degree. C. The residue was taken up with 
12 ml of ethanol and after the addition of 9.2 g of the triethyl ester of 
ortho formic acid and 5.8 g of aniline it was boiled for 5 hours. 
Yield: 7.2 g, 
Mp: 311.degree.-312.degree. C. (decomposition, hydroxy propionitrile). 
IR bands: 695, 735, 790, 820, 845, 885, 970, 1040, 1180, 1215, 1255, 1300, 
1335, 1350, 1375, 1480, 1500, 1590, 1610, 1635, 1660, 2860-3160, 3500 
cm.sup.-1. 
EXAMPLE 43 
Anhydro-2-(2-anilinovinyl)-3-(3-sulfopropyl)-benzoxazolium hydroxide. 
Prepared similarly to Example 42 from 2-methyl-benzoxazole (7 g), Yield: 
5.7 g, Mp: 325.degree.-327.degree. C. (decomposition). 
IR bands: 695, 745, 765, 790, 880, 970, 1040, 1180, 1190, 1210, 1260, 1300, 
1330, 1380, 1405, 1480, 1500, 1590, 1615, 1660, 2860-3160,.about.3400 
cm.sup.-1 
EXAMPLE 44 
Sodium salt of 
5-[3-(3-sulfobutyl)-benzothiazolinylidene]-3-ethyl-rhodanine. 
18 g of 2-methyl-thiobenzothiazole and 17.2 g of 4-hydroxy-2-butane 
sulfonic acid in 35 ml of anisole were heated to 200.degree. C. for 2 
hours under distillation conditions. 
The residue was washed with ether after cooling and then taken up with 150 
ml of ethanol. 13.5 g of 3-ethyl-rhodanine and 10 ml of triethylamine were 
added. After 1 hour at room temperature and filtration, the solution was 
poured into 140 ml of water and the dye was precipitated with saturated 
sodium chloride solution. 
Yield: 3.4 g absorption maximum: 429 nm (log .epsilon.=4.78). 
EXAMPLE 45 
Anhydro-3-(3-sulfopropyl)-3'-methyl-thiacyanine hydroxide. 1.7 g of 
2-mercapto benzothiazole and 3 g of 3-hydroxy-1-propane sulfonic acid in 3 
ml of m-cresol were heated to 175.degree. C. for from 7 to 8 hours. After 
cooling, 3.3 g of 2,3-dimethyl-benzothiazolium-p-tosylate, 30 ml of 
absolute ethanol and 5 ml of triethylamine were added. The reaction 
mixture was then heated to 50.degree. C. and left to stand for 1 hour. The 
dye which had crystallized was removed by suction filtration. 
Yield: 1.5 g, Mp: &gt;320.degree. C., absorption maximum: 422 nm (log 
.epsilon.=4.90). 
EXAMPLE 46 
3-ethyl-5-[1-methyl-3-(3-sulfopropyl)-5,6-dichlorobenzimidazolin-2-ylidene] 
-rhodanine; triethylamine salt: 
(a) 4.7 g of 1-methyl-2-mercapto-5,6-dichlorobenzimidazole, 6 g of 
3-hydroxy-1-propane sulfonic acid and 4 g of phenol heated to 175.degree. 
C. for 8 hours. The reaction product is dissolved in 40 ml of hot ethanol 
and filtered. 4 g of 3-ethyl rhodanine and 5 ml of triethylamine were 
added. The reaction mixture was left to stand for 2 hours and then suction 
filtered. 
Yield: 4.1 g, Mp: 228.degree.-230.degree. C. (ethanol/methanol). Absorption 
maximum: 423 nm (log .epsilon.=4.67). 
(b) The same as (a) from 2.3 g of 
1-methyl-2-mercapto-5,6-dichlorobenzimidazole and 6 g of 
3-hydroxy-1-propane sulfonic acid, but without the addition of phenol. 
Yield: 1.9 g, Mp: 227.degree.-229.degree. C. 
EXAMPLE 47 
Anhydro-2-methyl-3-(3'-sulfopropyl)-4,5-diphenyloxazolium hydroxide. 
Similarly to Example 6 from 9 g of 2-methyl-5,6-diphenyloxazole and 6 g of 
3-hydroxy-1-propane sulfonic acid; worked up with ethyl acetate and 
i-propanol. 
Yield: 4.9 g, Mp: 272.degree.-275.degree. C. 
IR bands: 695, 720, 765, 1045, 1210, 1450, 1610, 2900-3040, .about.3400 
cm.sup.-1. 
EXAMPLE 48 
Anhydro-3-(3-sulfopropyl)-3'-ethyl-thiocarbocyanine hydroxide. 
Similarly to Example 1 from 
2-(3-ethyl-2-benzothiazolinylidene)-1-propenyl]-benzothiazole and 
3-hydroxy-1-propane sulfonic acid. Mp: 244.degree.-247.degree. C., 
absorption maximum: 557 nm.