CH630355A5 - Process for preparing novel pyridylalkylsulphonic acid betaines - Google Patents

Description

The invention relates to a process for the preparation of new pyridylalkylsulfonic acid betaines.

Pyridylsulfonic acids and pyridylalkylsulfonic acids are known as additives for galvanic nickel baths. In US-PS 55 2 839 456 4-pyridylethanesulfonic acid is described together with other additives as brighteners. Although 2- and 4-pyridineethanesulfonic acids improve the gloss of deposited nickel coatings, they have no influence on their leveling. US Pat. No. 3,444,056 describes certain 60 quaternary compounds of pyridine-3-sulfonic acid as leveling-enhancing and brightening agents. However, the N-methylpyridine-3-sulfonic acid betaine and N-allylpyridine-3-sulfonic acid betaine mentioned in this patent are not fully satisfactory. The nickel-65 coating obtained becomes brittle and lackluster after a low ampere hour output / liter of nickel bath. This behavior of the bath cannot be avoided by any of the regeneration methods used in galvanization.

3rd

630355

The object of the invention is to provide additives for electroplating baths which preferably result in an extremely uniform nickel coating of excellent ductility under constant bath conditions.

The process of the invention for the preparation of new pyridylalkylsulfonic acid betaines of the general formula I

CVnS ° 3

©

10th

Lower alkyl radicals are understood to mean those with 1 to 4 carbon atoms. The term "halogen" includes bromine and fluorine atoms, but chlorine atoms are preferred. The halogen has an atomic weight of less than 80.

The pyridylalkylsulfonic acid betaines of the formula (I) are prepared by quaternization of a corresponding 2- or 4-pyridylalkylsulfonic acid (II-a) or its alkali metal salts (II-b), preferably the sodium salt:

CH2) nS ° 3H

®)

15

(Ha)

in which the substituent: - (CH2) nS03 © is in the 2- or 4-position of the pyridyl ring,

n has the value 1 or 2, and

R is methyl, methallyl, -CH2COOH, -CH2 (CH2) XCH2-S03Na-, where x is 1 or 2, sodium 2-hydroxy-propylsulfonate, sodium 2-hydroxybutylsulfonate, sodium - 3-hydroxybutylsulfonate, benzyl, halobenzyl, where the halogen has an atomic weight of less than 80, lower alkylbenzyl, where the lower alkyl radical contains 1 to 4 carbon atoms, or a benzyl group which is defined by the group:

20th

25th

0

(CH2) ns03

(Il-b)

• ch2-n ch) SO 2 n 3

©

is substituted, wherein the substituent: - (CH2) nSO3 © is in the 2 or 4 position of the pyridyl ring, and n has the value 1 or 2, is characterized in that a 2- or 4-pyridyl-alkylsulfonic acid Formula Il-a

(Il-a)

(Il-b)

where the substituent: - (CH2) nSO3 (H, Na) is in the 2- or 4-position of the pyridyl ring, Z is an alkali metal, and n is 1 or 2. The quaternization is carried out with a suitable quaternizing agent which is capable of introducing the substituent R mentioned on the ring nitrogen atom of the pyridyl function, e.g. with dimethyl sulfate, meth-allyl chloride, sodium chloroacetate, propane sultone, butane sultone, a suitable benzyl halide or a suitably substituted lower alkyl halide.

35 The compounds of the formulas (Il-a) and (Il-b) can be prepared in a known manner, e.g. by reacting 2- or 4-vinylpyridine with sodium bisulfite according to the method described in J. Am. Chem. Soc., Vol. 69, p. 2465 (1947) processes for the preparation of ethylsulfonic acids or by reacting a suitable haloalkylpyridine with sodium sulfite.

To prepare compounds of the formula (I) in which R is a methyl group, the starting compounds of the formula (II-a) or (Il-b) are reacted with dimethyl sulfate as qua-45 ternizing agent, this generally being carried out in a low stoichiometric amount Excess is used. To increase the reaction rate, higher temperatures can be used. Since dimethyl sulfate is a liquid at room temperature, there is usually no need to use an additional organic solvent for the quaternization reaction. The reaction proceeds as follows:

where Z is an alkali metal and n is 1 or 2,

reacted with a suitable quaternizing agent which is capable of introducing the substituent R on the ring nitrogen atom of the pyridyl function.

The aforementioned sodium 2-hydroxypropyl isulfonate, sodium 2-hydroxybutyl sulfonate and sodium 3-hydroxybutyl sulfonate groups can also be used as 3-Na sulfo-2-hydroxypropyl, 4-Na sulfo-2-hydroxybutyl - or 4-Na-sulfo - 3-hydroxybutyl groups. Similarly, the group: CH2 (CH2) xCH2S03Na at x = 1 as 3-Na-sulfopropyl group and at x = 2 as 4-Na-sulfobutyl group.

55

60

65

630355

4th

CH.,) SO-H â n J

+ Me2S04

(Il-a)

(CH) SO 2 n 3

0

For the preparation of compounds of formula (I) in which R is a -CH2COOH group, approximately equimolar amounts of the starting compound (II-b) and a haloacetic acid in the form of an alkali metal salt, e.g. the sodium salt (III) is reacted in an aqueous solvent, preferably under reflux. The reaction mixture containing the resulting alkali metal salt is then generally cooled and treated with a suitable mineral acid, such as hydrochloric acid, in order to convert the salt (IV) into the corresponding acid (V). The reaction proceeds as follows:

(CH2) nS03Na is

20th

Cl-CH2COONa

(Il-b)

CH2COONa

<CH2> nS03e

(HD

HCl

CJCH,) SO-

©

I ©

CH2COOH

(IV)

(V)

Compounds of formula (I) in which R is a benzyl, halobenzyl or lower alkylbenzyl group are prepared in a similar manner. The starting compound (II-b) is treated with a suitable benzyl halide (VI), e.g. Benzyl chloride, halobenzyl chloride or a lower alkyl benzyl chloride, preferably reacted in water under reflux. The desired N-benzyl-substituted product (VII) is obtained by cooling and treatment with a mineral acid:

50

(• Il-b) + C1-CH2

-Cte

HCl

CT

10th

(ch) so ® 2 n 3

r / =

CH

R '= H, halogen, lower alkyl group

Compounds of the formula (I) in which R is a methallyl group are quaternized in a similar way to compounds

65 in which R is a benzyl group, but methallyl chloride is used as the quaternizing agent.

Compounds of the formula (I) in which R is a -CH2- (CH2) x (CH2) S03Na Grappe are quaternized

5

630355

rank of compound (Il-b) with propane sultone or butane sultone (VIII), preferably in an aqueous solvent. Elevated temperatures can be used to accelerate the reaction. The reaction mixture, preferably after prior concentration, is treated with a mineral acid to counteract the sodium ion content and then reacted with suitable bases providing sodium ion, e.g. with sodium methylate in methanol to produce the desired sodium alkyl sulfonate derivative (IX). Similarly, compounds of formula (I) in which R is a sodium 2-hydroxypropyl sulfonate, sodium 2-hydroxybutyl sulfonate or sodium 3-hydroxybutyl sulfonate group are quaternized with (II-b) with the sodium salt a suitable halohydroxyalkyl sulfonic acid, as explained below for sodium 2-hydroxypropyl sulfonate (X):

(Il-a) +

(CH) / 2'x h2c

\ o -

\

/

CH «-

(X «1,2) (VIII)

h2o

10th

IS

->

(CH2) nS0 ©

Œ2- (CH2) x- <H2S03Na (IX)

• (n-b) +

OH

I.

h2o

Cl-O ^ -CH- CH2-S03Na)

A

CX)

HCl Na

^ 2 ^ nS03

©

CH2-CH-CH 2-S O ^ îîa CH

(XI)

For the preparation of compounds of formula (I) in which R is one with the group

© / ^ V <«2) nso3 ©

is substituted benzyl group, a, α'-dichloro xylene in the o-, m- or p-form is preferably reacted with at least two stoichiometric equivalents of the compound (II-b) in an aqueous solvent. Elevated temperatures are preferably used to accelerate the reaction. After the reaction has ended, the reaction mixture is generally cooled and treated with a mineral acid, whereupon the desired products are obtained by customary means

Refurbishment wins. With a, a'-dichloro-p-xylene, the described quaternization proceeds as follows:

55

60

65

630 355

2 (H-b) + Ci-CH,

h20

HCl

The compounds of the formula (I) usually give an extremely uniform and even nickel coating of excellent ductility when used as additives for conventional galvanic nickel baths. The compounds can be used in the nickel baths either alone or in combination with other additives that promote gloss or leveling. An optimal gloss is e.g. in combination with known brighteners, such as saccharin, diarylsulfonimides, naphthalene trisulfonic acids or sulfonates, and acetylene compounds, such as propargyl alcohol. The latter compound in particular promotes the leveling effect of the compounds which can be prepared according to the invention. The compounds of formula (I) can also be used together with conventional wetting agents, e.g. with sodium lauryl sulfate or other ionic or non-ionic agents that reduce surface tension. The galvanic baths can also contain conventional buffer additives, e.g. Boric acid or tartrate.

In general, the electroplating baths contain an acidic solution of a nickel salt, such as nickel sulfate, nickel sulfamate, nickel fluoroborate, nickel chloride or nickel acetate. Mixtures of these salts can usually also be used. Typical nickel baths in which the compounds which can be prepared according to the invention can be used are described in US Pat. No. 3,444,056. The concentration of the compounds which can be prepared according to the invention is 0.05 to 2.0 g / liter, in particular approximately 0.1 to 0.5 g / liter bath. Other preferred parameters are a bath temperature of approximately 50 to 60 ° C., a pH of approximately 3.5 to 5.0, in particular approximately 4.5, and a current density of approximately 1 to 10 A / dm2. The bathroom can e.g. mechanically or by introducing air. In the latter case, the use of a non-foaming wetting agent is preferred.

The electroplated nickel baths of the invention normally provide an extremely even and shiny Nikkei coating. Preferred additives of the formula (I) are compounds in which R is an unsubstituted benzyl group or a benzyl group which corresponds to the group:

example 1

taVn!

so.

©

is substituted, e.g. 2- [N-Benzylpyridyl- (2)] - ethanesulfonic acid betaine and 1,2-bis- [2- (2-sulfoethyl) pyridinium- (l) -methyl] -benzene.

The examples illustrate the invention.

20th

25th

at

© I

ch ch -so 2 2 3

G

ch2-cooh

A. 2- [N-Carboxymethyl-pyridyl- (2)] ethanesulfonic acid betaine 23.3 g (0.2 mol) sodium chloroacetate, 41.8 g (0.2 mol)

Sodium 2-pyridylethanesulfonate and 50 g of water are refluxed for 30 hours. After cooling to 20 ° C, the reaction mixture is treated with 250 g of concentrated hydrochloric acid. The crystalline sodium chloride is then suctioned off and the solution is concentrated under reduced pressure. to dryness and take up the residue with 350 ml of 35 methanol. 27.5 g of the desired compound, which crystallizes at room temperature, are filtered off on a suction filter and dried in vacuo at 110 ° C; Dec: 214 ° C.

B. 2- [N-Carboxymethyl-pyridyl- (4)] -ethanesulfonic acid bed is similarly used using equivalents

40 quantities of sodium 4-pyridylethanesulfonate and sodium chloroacetate were prepared as starting compounds; Dec: 234 ° C.

C. [N-Carboxymethyl-pyridyl- (4)] methanesulfonic acid betaine is similarly used using equivalents

45 quantities of sodium 4-pyridyl methanesulfonate and sodium chloroacetate prepared as starting compounds; Dec .: 290 ° C.

50

55

Example 2

ch2ch2-so3®

6o A. 2- [N-methyl-pyridyl- (2)] - ethanesulfonic acid betaine

55 g (0.29 mol) of 2-pyridylethanesulfonic acid and 40.7 g (0.32 mol) of dimethyl sulfate are heated to 150 to 155 ° C. After 2 hours, the reaction mixture is cooled to 20 ° C. and a mixture of 40 ml of ethanol and 40 ml of 65 isopropanol is added. After standing for 24 hours, the separated crude product is filtered off on a suction filter. After recrystallization from methanol twice, the white crystals are dried in vacuo at 80.degree. It

7

630355

16.8 g of the desired product are obtained; Dec: 209 ° C.

B. 2- [N-Methyl-pyridyl- (4)] ethanesulfonic acid betaine is similarly prepared using equivalent amounts of 4-pyridylethanesulfonic acid and dimethyl sulfate.

Example 3

CH.

A. 2- [N- (2-Methylbenzyl) pyridyl- (2)] ethanesulfonic acid betaine

41.8 g (0.2 mol) of sodium 2-pyridylethanesulfonate, 28.1 g (0.2 mol) of o-methylbenzyl chloride and 20 g of water are boiled under reflux for 5 hours. The reaction mixture is then allowed to cool to 20 ° C. and 250 g of concentrated hydrochloric acid are added. The separated sodium chloride is filtered off and the filtrate is evaporated to dryness under reduced pressure. The residue is then mixed with 200 ml of ethanol, the separated white crystal mass is filtered off on a suction filter and dried in vacuo at 110 ° C., 32 g of the desired compound being obtained; Dec .: 223 ° C.

B. 2- [N- (2-Methylbenzyl) pyridyl- (4)] ethanesulfonic acid betaine is similarly prepared using equivalent amounts of sodium 4-pyridylethanesulfonate and o-methyl-benzyl chloride as starting compounds: Dec. 241 ° C.

Example 4

l ^ N> -CH2S0

, ©

© Ì

U-Ç)

The following compounds were prepared by way of compounds: 2- [N-benzylipyridyl- (2)] -ethanesulfonic acid betaine;

Dec: 198 ° C. 2- [N-benzylpyridyl- (4)] ethanesulfonic acid betaine;

5 dec: 234 ° C.

2- [N- (2-chlorobenzyl) pyridyl- (2)] ethanesulfonic acid betaine; Dec .: 238 ° C.

2- [N- (4-chlorobenzyl) pyridyl- (2)] ethanesulfonic acid betaine; Dec .: 201 ° C.

io 2- [N- (2-chlorobenzyl) pyridyl- (4) l -ethanesulfonic acid betaine; Dec .: 237 ° C.

15

20th

Û-

Example 6

@

-CH, CH, -SO- "yy- 2 2 3

0

CH2CH2CH2-S03Na

A. 2- [N- (3-Na-sulfopropyl) pyridyl- (2)] - ethanesulfonic acid-25 betaine

41.8 g (0.2 mol) of sodium 2-pyridylethanesulfonate, 30.5 g (0.25 mol) of propane sultone, 200 g of methanol and 15 g of water are heated to 65 ° C. for 7 hours. The reaction mixture is then concentrated under reduced pressure and the residue is mixed with 200 ml of concentrated hydrochloric acid. The separated sodium chloride is filtered off and the mother liquor is evaporated to dryness. The oily residue is dissolved in 200 ml of methanol and left to stand for 2 days. Any 2-pyridylethanesulfonic acid which separates out during this time is filtered off, whereupon the filtrate is neutralized with a 30 percent sodium methylate solution in methanol. The deposited white salt is filtered off and dried in vacuo at 110 ° C., 17 g of the desired compound being obtained; Dec: 228 ° C.

40 B. The procedure of Example 6A. is repeated, but using an equivalent amount of butane sultone; instead of propane sultone. In this way, 2- [N- (4 - Na-sulfobutyl) pyridyl- (2)] - ethanesulfonic acid betaine is formed.

C. Following the procedure of Example 6A. the following compounds are prepared using equivalent amounts of the corresponding starting compounds: [N- (3-Na-sulfopropyl) pyridyl- (4)] methanesulfonic acid betaine and

2- [N- (4-Na-Sulfobutyl) pyridyl- (4)] -ethanesulfonic acid betaine.

45

50

[N-Benzyl-pyridyl- (2)] methanesulfonic acid betaine

17.3 g (0.1 mol) of sodium 2-pyridyl methanesulfonate, 12.7 g (0.1 mol) of benzyl chloride and 13 g of water are boiled under reflux at 100 to 105 ° C for 2 hours. The reaction mixture is then allowed to cool to 20 ° C. and 100 ml of concentrated hydrochloric acid are added. The separated sodium chloride is filtered off and the solution is evaporated to dryness. The residue is then mixed with 100 ml of ethanol, the white crystals which have separated out are filtered off and dried in vacuo at 110 ° C., 13.7 g of the desired compound being obtained; Dec: 230 ° C.

Example 5

According to the procedure of Examples 3 and 4, using equivalent amounts of the corresponding components

55

60

Example 7

ch2ch2so ©

CH2-CH (OH) -CH2-S03 Na

A. 2- [N- (3-Na-Sulfo-2-hydroxypropyl) pyridyl- (2)] - ethane-sulfonic acid betaine 65 20.9 g (0.1 mole) sodium 2-pyridylethane sulfonate, 19.7 g (0.1 mol) of sodium 3-chloro-2-hydroxypropylsulfonate (1) and 20 ml of water are heated at 95 ° C. for 6 hours. The reaction mixture is then concentrated under reduced pressure

630355

and mix the residue with 100 ml of concentrated hydrochloric acid. The insoluble sodium chloride is filtered off and the mother liquor is evaporated to dryness. The oily residue is taken up in 100 ml of methanol and left to stand for 2 days. Any 2-pyridylethanesulfonic acid which separates out during this time is filtered off, whereupon the filtrate is neutralized with a 30 percent sodium methylate solution in methanol. The white salt which has separated out is filtered off and dried in vacuo at 110 ° C., 11 g of the desired compounds being obtained; Dec .: 183 ° C.

B. The procedure of Example 7-A is repeated, but equivalent amounts of suitable starting compounds are used to prepare the following compounds: 2- [N- (4-N a-sulfo-2-hydroxybutyl) pyridyl- (2)] - ethanesulfonic acid betaine;

2- [N- (4-Na-Sulfo-3-hydroxybutyl) pyridyl- (4)] - ethanesulfone-

acid betaine and [N- (3-Na-sulfo-2-hydroxypropyl) pyridyl- (4)] methanesulfonic acid betaine.

Example 8

A. 1,4-bis- [2- (2-sulfoethyl) pyridirdum- (1) methyl] benzene 62.8 g (0.3 mol) sodium 2-pyridylethanesulfonate, 17.5 g

(0.1 mol) a, a'-dichloro-p-xylene and 50 g of water are heated at 100 to 105 ° C for 4 hours. The reaction mixture is then cooled and 200 g of concentrated hydrochloric acid are added. The separated sodium chloride is filtered off and the filtrate is evaporated to dryness under reduced pressure. The residue is then mixed with 200 ml of methanol, the impure crystals which have separated out are filtered off, dissolved in 120 ml of water at 20 ° C. and precipitated out again by adding 480 ml of ethanol. The white crystal mass is filtered off and dried in vacuo at 110 ° C., 26 g of the desired compound being obtained; Dec .:> 350 ° C.

B. In the same way, using equivalent amounts of appropriate starting compounds, the following compounds are prepared:

1,2-bis- [2- (2-sulfoethyl) pyridinium (1) methyl] benzene;

Dec .: 248 ° C.

1,3-bis- [2- (2-sulfoethyl) pyridinium (1) methyl] benzene;

Dec .: 251 ° C.

1,4-bis- [4- (2-sulfoethyl) pyridinium (1) methyl] benzene;

Dec .: 258 ° C.

Example 9

Typical galvanic nickel baths are specified below in which the compounds of the formula (I) can be used. In addition to the compounds which can be prepared according to the invention, any other compounds of the formula (I) which can be prepared according to the invention can also be used.

A

Nickel sulfate. 7H20

310

g / 1

Nickel chloride. 6H20

50

g / 1

s boric acid

40

g / 1

Lauryl sulfate

0.2

g / 1

Saccharin

2.0

g / 1

2- [N-Benzylpyridyl- (2)] - ethanesulfonic acid betaine

0.3

g / 1

temperature

50-60 ° C

Current density 1-7 A / dm2

15 pH 4.6

B

Nickel sulfate. 7HaO

310

g / 1

20 nickel chloride. 6H20

50

g / 1

Boric acid

40

g / 1

Lauryl sulfate

0.2

g / 1

Sodium saccharine

1.0

g / 1

25 1,3,6-naphthalene trisulfonic acid (sodium salt)

2- [N-Benzylpyridyl- (4)] - ethanesulfonic acid betaine

30 pH

Temperature current density

C.

Nickel sulfate. 7H20 nickel chloride. 6H20 boric acid

40

Lauryl sulfate

Dibenzylsulfonimide

Propargyl alcohol

45 l, 2-bis- [2- (2-sulfoethyl) pyridinium (l) methyl] benzene pH

Temperature so current density

Example 10

A. The procedure of Example 3-A is repeated, but using 18 g (0.2 mol) of methallyl chloride instead of

55 o-methylbenzyl chloride for the preparation of 2- [N- (2-methyl-propen-2-yl) pyridyl- (2)] -ethanesulfonic acid betaine (2- [N-meth-allyl-pyridyl- (2)] - ethanesulfonic acid betaine ); Dec .: 196 ° C.

B. 2- [N- (2-Methylpropen-2-yl) pyridyl- (4)] - ethanesulfonic acid betaine (2- [N-methallyl-pyridyl- (4)] -ethanesulfonic acid-

60 betaine); Dec: 208 ° C is obtained in a similar manner by using equivalent amounts of sodium 4-pyridyl ethane sulfonate and methallyl chloride as starting compounds.

1.0 g / 1

0.3 g / 1 4.6 50-60 ° C 1-7 A / dm2

280

g / l

40

g / 1

40

g / 1

0.2

g / 1

8.0

g / 1

0.04

g / 1

0.15 g / 1 4.6 50-60 ° C 1-7 A / dm2.

v

Claims (8)

630355 2nd PATENT CLAIMS 1. Process for the preparation of new pyridylalkyl sulfonic acid betaines of the general formula I CH_) SO © 2 n 3 (i) -o-xylene to 1,2-bis- [2- (2-sulfoethyl) pyridinium (l) methyl] - benzene. 6. Galvanic bright nickel bath containing at least one nickel salt in aqueous acid solution, characterized in that it additionally contains at least one compound of general formula I prepared according to claim 1 CH_) SO © / n 3 in which the substituent: - (CH2) nS03 © is in the 2- or 4-position of the pyridyl ring, n has the value 1 or 2, and R is methyl, methallyl, -CH2COOH, -CH2 (CH2) XCH2-S03Na-, where x is 1 or 2, sodium 2-hydroxy-propylsulfonate, sodium 2-hydroxybutylsulfonate, sodium - 3-hydroxybutylsulfonate, benzyl, halobenzyl, where the halogen has an atomic weight of less than 80, lower alkylbenzyl, where the lower alkyl radical contains 1 to 4 carbon atoms, or a benzyl group which is defined by the group: 10th 15 (I) -CH2-N CH_) SO, 2 n 3 © in which the substituent: - (CH2) nS03 © is in the 2- or 4-position of the pyridyl ring, n is 1 or 2, and 20 R is methyl, methallyl, -CH2COOH, -CH2 (CH2) XCH2-S03Na-, where x is 1 or 2, sodium 2-hydroxy-propylsulfonate, Sodium 2-hydroxybutylsulfonate, sodium 3-hydroxybutylsulfonate, benzyl, halobenzyl, where the halogen has an atomic weight of less than 80, lower 25-alkylbenzyl, where the lower alkyl radical contains 1 to 4 carbon atoms, or one Benzyl group is by the group 30th is substituted, the substituent: - (CH2) nSO3 © being in the 2- or 4-position of the pyridyl ring, and n being 1 or 2, characterized in that a 2- or 4-pyridyl-alkylsulfonic acid of the formula Il-a CH_) SO n 3 © (II-a) 35 is substituted, the substituent: - (CH2) nSO3 © being in the 2- or 4-position of the pyridyl ring, and n being 1 or 2, contains in a concentration of 0.05 to 2.0 g / liter. 7. Bath according to claim 6, characterized in that 40 it 2- [N-benzylpyridyl- (2)] - ethanesulfonic acid betaine in one Contains concentration from 0.1 to 0.5 g / liter. 8. Bath according to claim 6, characterized in that it contains 2- [N-benzylpyridyl- (4)] - ethanesulfonic acid betaine in a concentration of 0.1 to 0.5 g / liter. 45 9. Bath according to claim 6, characterized in that it is l, 2-bis- [2- (2-sulfoethyl) pyridinium (l) methyl] benzene in a concentration of 0.1 to 0.5 g / Liter contains. (Il-b) where Z is an alkali metal and n is 1 or 2, reacted with a suitable quaternizing agent which is capable of introducing the substituent R on the ring nitrogen atom of the pyridyl function. 2. The method according to claim 1, characterized in that in compounds of the formula II-b Z is sodium. 3. The method according to claim 1, characterized in that sodium 2-pyridylethanesulfonate under reflux with benzyl chloride to 2- [N-benzylpyridyl- (2)] - ethanesulfonic acid betaine. 4. The method according to claim 1, characterized in that sodium 4-pyridylethanesulfonate under reflux with benzyl chloride to give 2- [N-benzylpyridyl- (4)] - ethanesulfonic acid betaine. 5. The method according to claim 1, characterized in that sodium 2-pyridylethanesulfonate with a, a'-dichloro- 50